TS-7682

From Technologic Systems Manuals
TS-7682
ts-7682.gif
Product Page
Product Images
Specifications
Documentation
Schematic
Mechanical Drawing
FTP Path
Processor
Freescale i.MX286
454MHz ARMv5TE ARM926EJ-S
CPU Datasheet
Note: The TS-7682 Rev. A has not been officially released as a standard product, it is currently in sampling phase. Parts of this manual may be incorrect and are subject to change.


1 Overview

The TS-7682 Rev. A has not been officially released as a standard product, it is currently in sampling phase. This is a small embedded board with a Freescale i.MX286 454Mhz ARM9 CPU with 128-256MB DDR2.

2 Getting Started

A Linux PC is recommended for development, and will be assumed for this documentation. For users in Windows or OSX we recommend virtualizing a Linux PC. Most of our platforms run Debian and if there is no personal distribution preference this is what we recommend for ease of use.

Virtualization

Suggested Linux Distributions

It may be possible to develop using a Windows or OSX system, but this is not supported. Development will include accessing drives formatted for Linux and often Linux based tools.

2.1 Booting up the board

WARNING: Be sure to take appropriate Electrostatic Discharge (ESD) precautions. Disconnect the power source before moving, cabling, or performing any set up procedures. Inappropriate handling may cause damage to the board.

The TS-7682 has an input voltage range of 8 to 28 VDC through the main power connector which offers screw terminals for secure wiring. The TS-7682 will require approximately 1.4W at idle. An ideal power supply for the TS-7682 will allow up to 5W to allow peripherals to be powered as well.

Once power is applied the console port will begin outputting output on the bootup process. The output will be similar to the text below:

HTLLCLLC

U-Boot 2014.10-g4d36657 (Dec 07 2016 - 12:19:27)

CPU:   Freescale i.MX28 rev1.2 at 454 MHz
BOOT:  SSP SPI #2, master, 3V3 NOR
I2C:   ready
SPI:   ready
DRAM:  256 MiB
MMC:   MXS MMC: 0, MXS MMC: 1
SF: Detected IS25LQ016B with page size 256 Bytes, erase size 4 KiB, total 2 MiB
*** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   FEC0 [PRIME]
NO CHRG jumper is set, not waiting for SuperCaps to charge
Booting from the SD Card ...
** File not found /boot/boot.ub **
** File not found /boot/ts7682-fpga.vme **
3336928 bytes read in 1245 ms (2.6 MiB/s)
20378 bytes read in 265 ms (74.2 KiB/s)
## Booting kernel from Legacy Image at 42000000 ...
   Image Name:   Linux-3.14.28-g1a4251b
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    3336864 Bytes = 3.2 MiB
   Load Address: 40008000
   Entry Point:  40008000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 41000000
   Booting using the fdt blob at 0x41000000
   Loading Kernel Image ... OK
   Loading Device Tree to 4fb4b000, end 4fb52f99 ... OK

Starting kernel ...



Welcome to Debian GNU/Linux 8 (jessie)!

[ SKIP ] Ordering cycle found, skipping LSB: RPC portmapper replacement
         Expecting device dev-ttyAMA0.device...
[  OK  ] Reached target Remote File Systems (Pre).
...
[  OK  ] Started Update UTMP about System Runlevel Changes.

Debian GNU/Linux 8 imx28 ttyAMA0

imx28 login:

The i.MX28 internal bootrom prints out the strings of letters to indicate various stages of its internal process. The U-Boot build date reflects when U-Boot was built and serves as a revision indicator. A change to the kernel or filesystem will not affect this date.

2.2 Get a Console

2.2.1 Serial Console

The TS-7682 includes a USB device port, this uses a 8051 based microcontroller to create a serial device on a host PC. The serial console is provided through this port at 115200 baud, 8n1, with no flow control.


Console from Linux

There are many serial terminal applications for Linux, three common used applications are 'picocom', 'screen', and 'minicom'. These examples demonstrate all three applications and assume that the serial device is "/dev/ttyUSB0" which is common for USB adapters. Be sure to replace the serial device string with that of the device on your workstation.

'picocom' is a very small and simple client.

picocom -b 115200 /dev/ttyUSB0


'screen' is a terminal multiplexer which happens to have serial support.

screen /dev/ttyUSB0 115200


Or a very commonly used client is 'minicom' which is quite powerful but requires some setup:

minicom -s
  • Navigate to 'serial port setup'
  • Type "a" and change location of serial device to '/dev/ttyUSB0' then hit "enter"
  • If needed, modify the settings to match this and hit "esc" when done:
     E - Bps/Par/Bits          : 115200 8N1
     F - Hardware Flow Control : No
     G - Software Flow Control : No
  • Navigate to 'Save setup as dfl', hit "enter", and then "esc"


Console from Windows

Putty is a small simple client available for download here. Open up Device Manager to determine your console port. See the putty configuration image for more details.

Device Manager Putty Configuration


3 U-Boot

U-Boot is used on this device as the bootloader to launch the full operating system. When the i.MX28 processor starts, it loads U-Boot from the on-board SPI flash. This allows creation of a custom boot image on either the SD, eMMC, NFS, or USB. U-Boot is a general purpose bootloader that is capable of booting into common Linux distributions, Android, Windows, or custom software OSes.

On a normal boot the output will be similar to this:

HTLLCLLC

U-Boot 2014.10-g4d36657 (Dec 07 2016 - 12:19:27)

CPU:   Freescale i.MX28 rev1.2 at 454 MHz
BOOT:  SSP SPI #2, master, 3V3 NOR
I2C:   ready
SPI:   ready
DRAM:  256 MiB
MMC:   MXS MMC: 0, MXS MMC: 1
SF: Detected IS25LQ016B with page size 256 Bytes, erase size 4 KiB, total 2 MiB

In:    serial
Out:   serial
Err:   serial
Net:   FEC0 [PRIME]
NO CHRG jumper is set, not waiting for SuperCaps to charge
Booting from the SD Card ...
** File not found /boot/boot.ub **
3336928 bytes read in 1245 ms (2.6 MiB/s)
20378 bytes read in 265 ms (74.2 KiB/s)
## Booting kernel from Legacy Image at 42000000 ...
   Image Name:   Linux-3.14.28-g1a4251b
   Image Type:   ARM Linux Kernel Image (uncompressed)
   Data Size:    3336864 Bytes = 3.2 MiB
   Load Address: 40008000
   Entry Point:  40008000
   Verifying Checksum ... OK
## Flattened Device Tree blob at 41000000
   Booting using the fdt blob at 0x41000000
   Loading Kernel Image ... OK
   Loading Device Tree to 4fb4b000, end 4fb52f99 ... OK

Starting kernel ...

3.1 U-Boot Environment

On the SPI flash U-boot has both the U-boot application and the U-boot environment. Our default build has 8KB of environment which can be used for variables and scripts to control booting your operating system. These commands are relevant to manipulating the environment:

# Print all environment variables
env print -a

# Sets the variable bootdelay to 5 seconds
env set bootdelay 5;

# Variables can also contain commands
env set hellocmd 'led red on; echo Hello world; led green on;'

# Execute commands saved in a variable
env run hellocmd;

# Commit env changes to the spi flash
# Otherwise changes are lost
env save

# Restore env to default
env default -a

# Remove a variable
env delete emmcboot

For a production environment the best option for setting depends on the number of units. For a smaller number of units it may be simplest to update any required commands manually. For example, a custom cmdline option like "debug":

env set cmdline_append rw rootwait console=ttyAMA0,115200 loglevel=3 debug
env save

3.2 U-Boot Commands

These commands are agnostic to the operating system that is running, but may be useful for testing or scripting:

# The most important command is 
help
# This can also be used to see more information on a specific command
help mmc

# Boots into the binary at $loadaddr.  This file needs to have
# the uboot header from mkimage.  A uImage already contains this.
bootm
# Boots into the binary at $loadaddr, skips the initrd, specifies
# the fdtaddr so Linux knows where to find the board support
bootm ${loadaddr} - ${fdtaddr}

# Get a DHCP address
dhcp
# This sets ${ipaddr}, ${dnsip}, ${gatewayip}, ${netmask}
# and ${ip_dyn} which can be used to check if the dhcp was successful

# These commands are mainly used for scripting:
false # do nothing, unsuccessfully
true # do nothing, successfully

# Control LEDs
led red on
led green on
led all off
led red toggle

# This command is used to copy a file from most devices
# Load kernel from SD
load mmc 0:2 ${loadaddr} /boot/uImage
# Load kernel from USB
usb start
load usb 0:1 ${loadaddr} /boot/uImage

# View the fdt from u-boot with fdt
load mmc 0:2 ${fdtaddr} /boot/imx28-ts7680.dtb
fdt addr ${fdtaddr}
fdt print

# Blindly jump into any memory location
# This is similar to bootm, but it does not use the 
# u-boot header
load mmc 0:2 ${loadaddr} /boot/custombinary
go ${loadaddr}

# Browse fat,ext2,ext3,or ext4 filesystems:
ls mmc 0:2 /

# Similar to devmem in Linux, read/write arbitrary memory
# using mw and md
# write
mw 0x10000000 0xc0ffee00 1
# read
md 0x10000000 1

# Test memory.  Typically just used in production
mtest

# Read newly inserted SD card
mmc rescan
# Read SD card size
mmc dev 0
mmcinfo

# The NFS command is similar to 'load', but used over the network
dhcp
env set serverip 192.168.0.11
nfs ${loadaddr} 192.168.0.11:/path/to/somefile

# Test ICMP
dhcp
ping 192.168.0.11

# Reboot
reset

# SPI access is through the SF command
# Be careful with sf commands since
# this is where u-boot and the FPGA bitstream exist
# Improper use can render the board unbootable
sf probe

# Delay in seconds
sleep 10

# It is possible to load HUSH scripts that have been created with mkimage
load mmc 0:2 ${loadaddr} /boot/ubootscript
source ${loadaddr}

# Most commands have return values that can be used to test
# success, and HUSH scripting supports comparisons similar to
# test in Bash, but much more minimal
if load mmc 0:2 ${fdtaddr} /boot/uImage;
	then echo Loaded Kernel
else
	echo Could not find kernel
fi

# Commands can be timed with "time" similar to Linux
time sf probe

# Print U-boot version/build information
version

3.3 Modify Linux Kernel cmdline

The Linux kernel cmdline can be customized by modifying the cmdline_append variable. Keeping the default options here is recommended, but additional arguments can be appended to this variable.

env set cmdline_append rw rootwait console=ttyAMA0,115200 loglevel=3
env save

You can also change the kernel command line from the onboard Linux. From the board's shell prompt run:

apt-get update && apt-get install u-boot-tools -y
echo "env set cmdline_append rw rootwait console=ttyAMA0,115200 quiet" > /boot/boot.scr
mkimage -A arm -T script -C none -n 'tsimx28 boot script' -d /boot/boot.scr /boot/boot.ub

The boot.scr includes the plaintext commands to be run in u-boot on startup, and mkimage adds a checksum and header to this file which can be loaded by u-boot. The ub file should not be manually modified.

3.4 Linux NFS Boot

U-boot includes support for NFS which can be used to load your kernel, device tree binary, and root filesystem. Our default environment contains the nfsboot command which can be updated to boot NFS on your network:

# Set this to your NFS server ip
env set nfsip 192.168.0.11;

# Set this to your NFS root path.  The server root should be accessible at this path.
env set nfsroot /nfsroot/rootfs/
env save

To boot your NFS root:

# Boot to NFS once
run nfsboot;

# To make the NFS boot the persistent default
env set bootcmd run nfsboot;
env save

3.5 Linux USB Boot

By default, U-Boot will attempt to read a U-Boot script from a USB drive when the U-Boot jumper is set. It copies /tsinit.ub into memory and jumps in to the script. To make a bootable drive, create a single ext3 partition on a USB drive and unpack the rootfs tarball located here

The one addition is to create the tsinit.ub file in the root of the USB drive. In order to do this, a U-Boot script must be created and then converted to the .ub format. This process requires a set of U-Boot specific tools. These are available on most every linux distribution, the instructions below are for Debian, either run on a host PC or on the target. See the package installation documentation for other respective distributions.

Install U-Boot tools in Debian

apt-get update && apt-get install u-boot-tools -y

Create the file tsinit.scr in the root of the USB drive with the linux filesystem:

# Prepare with:
# mkimage -A arm -T script -C none -n 'imx28 usb' -d tsinit.scr tsinit.ub

# DO NOT MANUALLY EDIT THE .UB FILE

if load usb 0:1 ${loadaddr} /boot/ts${model}-fpga.vme;
        then fpga load 0 ${loadaddr} ${filesize};
fi;

load usb 0:1 ${fdtaddr} /boot/imx28-ts${model}.dtb;

load usb 0:1 ${loadaddr} /boot/uImage;

setenv bootargs root=/dev/sda1 ${cmdline_append};
bootm ${loadaddr} - ${fdtaddr};

Then in the same directory generate the tsinit.ub file:

mkimage -A arm -T script -C none -n 'imx28 usb' -d tsinit.scr tsinit.ub

You may need to install u-boot-tools or the equivalent package for your distribution.

3.6 U-Boot Recovery

The development tool, TS-9468, can be used to recover the SBC. Set the flip switch in the "Up" position so it lights up red when powered on to boot from the SPI flash on the TS-9468; the TS-9468 may not ship with a switch, without the switch populated the TS-9468 will automatically boot to the SPI flash on the TS-9468. Use the instructions in Update U-Boot to download and copy in the latest U-Boot binary to SD and boot the unit. And instead of the command listed, use the following:

env set spi onboard
run update-uboot

The script output will include a message saying that it is writing to the onboard SPI flash. The environment variable "spi" can be set to "offboard" in order to force writing to the TS-9468 in order to update the binary on there. Note that if the variable is not set, the script will write to the SPI flash of the SBC or TS-9468 based on the switch position (if there is one).

3.7 Update U-Boot

WARNING: Installing your own u-boot is not recommended and may cause the board to fail to boot.

The latest U-Boot binary can be downloaded from the TS-7682 FTP site. Copy this file to /boot/u-boot.sb on the 2nd partition of the SD card. The SPI flash can be updated by inserting that SD card in to the TS-7682, setting the U-Boot and SD card jumpers, and powering up the unit. At the U-Boot prompt, the following command can be used:

run update-uboot

The above script will use the /boot/u-boot.sb file from the SD card or eMMC, depending on the state of the SD Boot jumper.

3.8 U-boot Development

We do provide our u-boot sources, but we do not recommend rebuilding a custom uboot if it can be avoided. If you still want to proceed with building a custom u-boot, use the master branch from the github here: https://github.com/embeddedarm/u-boot


Set the PATH variable to include the cross compiler used for the TS-7682. The U-Boot binary can be built with the following:

./build-mx28 ts7680

This will output a u-boot.sb file you can use to write the SPI flash as listed in the Update U-Boot section. Note that "ts7680" is correct, the same binary is used for both the TS-7680 and TS-7682.

4 Debian Configuration

For development, it is recommended to work directly in Debian on the SD card. Debian provides many more packages and a much more familiar environment for users already versed in Debian. Through Debian it is possible to configure the network, use the 'apt-get' suite to manage packages, and perform other configuration tasks. Out of the box the Debian distribution does not have any default username/password set. The account "root" is set up with no password configured. It is possible to log in via the serial console without a password but many services such as ssh will require a password set or will not allow root login at all. It is advised to set a root password and create a user account when the unit is first booted.

Note: Setting up a password for root is only feasible on the uSD image.

It is also possible to cross compile applications. Using a Debian host system will allow for installing a cross compiler to build applications. The advantage of using a Debian host system comes from compiling against libraries. Debian cross platform support allows one to install the necessary development libraries on the host, building the application on the host, and simply installing the runtime libraries on the target device. The library versions will be the same and completely compatible with each other. See the respective Debian cross compiling section for more information.

4.1 Configuring the Network

From almost any Linux system you can use 'ip' command or the 'ifconfig' and 'route' commands to initially set up the network.

# Bring up the CPU network interface
ifconfig eth0 up

# Or if you're on a baseboard with a second ethernet port, you can use that as:
ifconfig eth1 up

# Set an ip address (assumes 255.255.255.0 subnet mask)
ifconfig eth0 192.168.0.50

# Set a specific subnet
ifconfig eth0 192.168.0.50 netmask 255.255.0.0

# Configure your route.  This is the server that provides your internet connection.
route add default gw 192.168.0.1

# Edit /etc/resolv.conf for your DNS server
echo "nameserver 192.168.0.1" > /etc/resolv.conf

Most networks will offer a DHCP server, an IP address can be obtained from a server with a single command in linux:

Configure DHCP in Debian:

# To setup the default CPU ethernet port
dhclient eth0
# Or if you're on a baseboard with a second ethernet port, you can use that as:
dhclient eth1
# You can configure all ethernet ports for a dhcp response with
dhclient


Systemd provides a networking configuration option to allow for automatic configuration on startup. Systemd-networkd has a number of different configuration files, some of the default examples and setup steps are outlined below.

/etc/systemd/network/eth.network

[Match]
Name=eth*

[Network]
DHCP=yes

To use DHCP to configure DNS via systemd, start and enable the network name resolver service, systemd-resolved:

systemctl start systemd-resolved.service 
systemctl enable systemd-resolved.service
ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf


For a static config create a network configuration for that specific interface.

/etc/systemd/network/eth0.network

[Match]
Name=eth0

[Network]
Address=192.168.0.50/24
Gateway=192.168.0.1
DNS=192.168.0.1

For more information on networking, see Debian and systemd's documentation:

4.1.1 WIFI Client

If connecting to a WPA/WPA2 network, a wpa_supplicant config file must first be created:

wpa_passphrase yournetwork yournetworkpassphrase > /etc/wpa_supplicant/wpa_supplicant-wlan0.conf


Create the file /lib/systemd/system/wpa_supplicant@.service with these contents

[Unit]
Description=WPA supplicant daemon (interface-specific version)
Requires=sys-subsystem-net-devices-%i.device
After=sys-subsystem-net-devices-%i.device

[Service]
Type=simple
ExecStart=/sbin/wpa_supplicant -c/etc/wpa_supplicant/wpa_supplicant-%I.conf -i%I

[Install]
Alias=multi-user.target.wants/wpa_supplicant@%i.service


Create the file /etc/systemd/network/wlan0.network with:

[Match]
Name=wlan0

[Network]
DHCP=yes

See the systemctl-networkd example for setting a static IP for a network interface. The wlan0.network can be configured the same way as an eth.network.


To enable all of the changes that have been made, run the following commands:

systemctl enable wpa_supplicant@wlan0
systemctl start wpa_supplicant@wlan0
systemctl restart systemd-networkd

4.1.2 Host a WIFI Access Point

First, hostapd needs to be installed in order to manage the access point on the device:

apt-get update && apt-get install hostapd -y


Note: The install process will start an unconfigured hostapd process. This process must be killed and restarted before a new hostapd.conf will take effect.

Edit /etc/hostapd/hostapd.conf to include the following lines:

interface=wlan0
driver=nl80211
ssid=YourAPName
channel=1
Note: Refer to the kernel's hostapd documentation for more wireless configuration options.


To start the access point launch hostapd:

hostapd /etc/hostapd/hostapd.conf &

This will start up an access point that can be detected by WIFI clients. A DHCP server will likely be desired to assign IP addresses. Refer to Debian's documentation for more details on DHCP configuration.

4.1.3 Cellular Data Network

4.1.3.1 MultiTech

The TS-7682 includes support for the MultiTech MTSMC-G2 or MTSMC-H5 which can connect to the internet using pppd. The modem is attached to the CN5 Header. The default UART interface for this modem is UART 4 and can be changed with the Crossbar interface, please see the Crossbar section for more information on setting this up. Presuming the default, the following command is used to set up a symlink for the instructions. This symlink can be changed as needed if a different UART is set up via the Crossbar.

ln -s /dev/ttyAPP4 /dev/ttymultidc

The modem needs to be brought out of reset before it can be used:

echo "211" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio211/direction
echo "1" > /sys/class/gpio/gpio211/value

Additionally, the DIO pin that connects to the RTS pin of the modem needs to be set to an output and driven low in order to allow communication with the modem:

echo "214" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio214/direction
echo "0" > /sys/class/gpio/gpio214/value

Note that when using higher baud rates, the CTS and RTS pins of the modem may need to be connected to UART CTS and RTS. See the FPGA Crossbar mux section for information on how to configure this.


The pppd application must be installed and any required modules loaded:

apt-get update && apt-get install -y ppp

This example is configured for T-Mobile in the US:

/etc/ppp/peers/tmobile


/dev/ttymultidc
noauth
115200
debug
usepeerdns
persist
defaultroute

connect "/usr/sbin/chat -v -f /etc/ppp/chatscripts/tmobile"
disconnect "/usr/sbin/chat -v -f /etc/ppp/chatscripts/tmobile-disconnect"

/etc/ppp/chatscripts/tmobile

TIMEOUT 10
ABORT 'BUSY'
ABORT 'NO ANSWER'
ABORT 'ERROR'

"" "\p\p\p\p\p\p\p\p\p\p\p\p+++\p\p\p\p\p\p\p\p\p\p\p\p"
"" "ATH0"

"OK" 'AT+CGDCONT=1,"IP","wap.voicestream.com"'

ABORT 'NO CARRIER'
OK 'ATD*99***1#'
CONNECT

/etc/ppp/chatscripts/tmobile-disconnect

"" "\K"
"" "+++ATH0"

Using a different carrier you will likely only need to replace wap.voicestream.com with the access point for your carrier.

To start pppd:

pppd call tmobile

# Or for more logging information:
# pppd nodetach call tmobile

This will create a ppp0 interface that can now be used as a standard network interface, and should set up a default route to the internet. For other carriers, typically you will only need a different access point listed in the AT+CGDCONT call, but further adjustments may be necessary.


Note: We have observed that the MTSMC-H5 connected to some networks has issues at or below 115200 baud. The issues observed are connection timeouts with the network itself. The connection between the modem and host device remain rock solid. While many applications are tolerant to the connection being reset, we have found some network downloads will abort without being able to recover. Running the unit at a faster baud rate, 230400 or higher, has been observed to eliminate this issue entirely. This does mean, however, that every time the device is started up, the modem must be issued an AT+IPR command (as noted below) at 115200 baud, then pppd started with the matched and higher baud rate in the peer script as shown above.


Faster Data Rates

While the MTSMC-G2 (GPRS) is limited to 115200 baud, the MTSMC-H5 (HDSPA) can communicate over serial up to 921600 allowing actual transfer rates around 80-90KB/s.

To set a custom baudrate in Linux, the method depends on the CPU and kernel support. More recent UART peripherals have a higher clock and a smarter driver, and can therefore use custom baud rates inherently. However, some systems require the use of 'setserial' using the spd_cust flag and some manual settings. When the spd_cust baud rate is set, Linux will re-purpose 38400 baud to use the set custom baud rate.


First, test the unit to see if it is possible to open up the UART with a higher baud rate:

picocom -b 921600 /dev/ttymultidc

If the higher baud is unsupported, picocom will return a failure similar to the following:

FATAL: failed to add device /dev/ttymultidc: Invalid baud rate

If the above error is received, then the method below using setserial must be used.

Otherwise, the port can be closed, re-opened at 115200 baud to communicate with the modem, and then the following command can be used to tell the cell modem to enter a higher baud rate:

AT+IPR=921600

Now the port can be closed everything will function at the higher baud rate. Be sure to update the providers file. Using the example T-Mobile configuration, edit /etc/ppp/peers/tmobile and change 115200 to 38400. Starting pppd will now allow communication around 80-90KB/s (depending on your local cell tower's availability).


Common Baud Rates
Divisor Rate
1 921600
2 460800
3 307200
4 230400
5 184320
6 153600
7 131657
8 115200

Larger divisors will also work, but this should cover the common range. Using the setserial command you can specify the divisor. For example, to reach 115200 with the alternative baud base:

setserial /dev/ttymultidc spd_cust baud_base 921600 divisor 8

Next you will need to tell the modem to communicate at the faster baud rates. You can use a client like picocom or minicom to connect directly to the modem to send it commands.

picocom -b 38400 /dev/ttymultidc

Even though we are talking at 115200, 38400 must be specified since we are using a custom baud_base. You can test communication with the modem again by typing "AT", pressing enter, and receiving "OK". To reconfigure the modem to the faster 921600 baud rate you can send it this command:

AT+IPR=921600

This will respond with OK, but now you will need to quit out of picocom (ctrl a,x) and reconfigure the baud base to use divisor 1:

setserial /dev/ttymultidc spd_cust baud_base 921600 divisor 1

The only change now needed is in your providers file. Using the example T-Mobile configuration , edit /etc/ppp/peers/tmobile and change 115200 to 38400. Starting pppd will now allow communication around 80-90KB/s (depending on your local cell tower's availability).


Troubleshooting

If you are not able to obtain a ppp connection there are a few values you can check:

Troubleshooting: Cell Signal

Make sure ppp is not running, and execute these commands to check the signal strength.

stty raw -echo speed 115200 -F /dev/ttymultidc 
cat /dev/ttymultidc &
echo -e "AT+CSQ\r\n" > /dev/ttymultidc 
killall cat

The return value should be something like "+CSQ: 9,2", or with no connection, +CSQ: 99,99. The second argument is the signal strengh which follows this table:

RSSI return values
0 -113 dBm or less
1 -111 dBm
2 to 30 -109 to -53dBm
31 -51dBm or greater
99 not known or detectable

If you return 99, make sure the antenna is connected and that you are in an area with good signal from your provider. Even without a valid SIM card you can have a good connection. If you are in another country, you may need to adjust the band for those supported by your carrier. The default value is appropriate for most US based carriers. Refer to the +WMBS command in your AT command guide for more options.


Troubleshooting: SIM card

If you have a good signal strength but are not obtaining a connection you can verify that the modem is able to read the subscriber number. This proves your SIM card is valid.

stty raw -echo speed 115200 -F /dev/ttymultidc 
cat /dev/ttymultidc &
echo -e "AT+CNUM\r\n" > /dev/ttymultidc 
killall cat

With a valid SIM this will return something like:

+CNUM: "","12345678901",129

If the SIM not detected you will only read ERROR. Make sure in this case that the card is inserted in the right direction so the pads on the card line up with the socket.

Troubleshooting: Other Options

If neither of the above steps get you connected you may want to contact your service provider for more information about where your connection attempts are failing.

4.2 Installing New Software

Debian provides the apt-get system which allows management of pre-built applications. The apt tools require a network connection to the internet in order to automatically download and install new software. The update command will download a list of the current versions of pre-built packages.

apt-get update

A common example is installing Java runtime support for a system. Find the package name first with search, and then install it.

root@ts:~# apt-cache search openjdk
jvm-7-avian-jre - lightweight virtual machine using the OpenJDK class library
freemind - Java Program for creating and viewing Mindmaps
icedtea-7-plugin - web browser plugin based on OpenJDK and IcedTea to execute Java applets
default-jdk - Standard Java or Java compatible Development Kit
default-jdk-doc - Standard Java or Java compatible Development Kit (documentation)
default-jre - Standard Java or Java compatible Runtime
default-jre-headless - Standard Java or Java compatible Runtime (headless)
jtreg - Regression Test Harness for the OpenJDK platform
libreoffice - office productivity suite (metapackage)
icedtea-7-jre-jamvm - Alternative JVM for OpenJDK, using JamVM
openjdk-7-dbg - Java runtime based on OpenJDK (debugging symbols)
openjdk-7-demo - Java runtime based on OpenJDK (demos and examples)
openjdk-7-doc - OpenJDK Development Kit (JDK) documentation
openjdk-7-jdk - OpenJDK Development Kit (JDK)
openjdk-7-jre - OpenJDK Java runtime, using Hotspot Zero
openjdk-7-jre-headless - OpenJDK Java runtime, using Hotspot Zero (headless)
openjdk-7-jre-lib - OpenJDK Java runtime (architecture independent libraries)
openjdk-7-source - OpenJDK Development Kit (JDK) source files
uwsgi-app-integration-plugins - plugins for integration of uWSGI and application
uwsgi-plugin-jvm-openjdk-7 - Java plugin for uWSGI (OpenJDK 7)
uwsgi-plugin-jwsgi-openjdk-7 - JWSGI plugin for uWSGI (OpenJDK 7)
                                                       

In this case you will want the openjdk-7-jre package. Names of packages are on Debian's wiki or the packages site.

With the package name apt-get install can be used to install the prebuilt packages.

apt-get install openjdk-7-jre
# More than one package can be installed at a time.
apt-get install openjdk-7-jre nano vim mplayer

For more information on using apt-get refer to Debian's documentation here.

4.3 Setting up SSH

To install ssh, install the package as normal with apt-get:

apt-get install openssh-server


Make sure the device is configured on the network and set a password for the remote user. SSH will not allow remote connections without a password or a valid SSH key pair.

passwd root
Note: The default OpenSSH server will not permit root to login via SSH as a security precaution. To allow root to log in via ssh anyway, edit the /etc/ssh/sshd_config file and add the line PermitRootLogin yes in the authentication section. This change will take effect after reboot or after sshd service restart.

After this setup it is now possible to connect from a remote PC supporting SSH. On Linux/OS X this is the "ssh" command, or from Windows using a client such as PuTTY.

Note: If a DNS server is not present on the target network, it is possible to save time at login by adding "UseDNS no" in /etc/ssh/sshd_config.

4.4 Starting Automatically

A systemd service can be created to start up headless applications. Create a file in /etc/systemd/system/yourapp.service

[Unit]
Description=Run an application on startup

[Service]
Type=simple
ExecStart=/usr/local/bin/your_app_or_script

[Install]
WantedBy=multi-user.target

If networking is a dependency add "After=network.target" in the Unit section. Once you have this file in place add it to startup with:

# Start the app on startup, but will not start it now
systemctl enable yourapp.service

# Start the app now, but doesn't change auto startup
systemctl start yourapp.service
Note: See the systemd documentation for in depth documentation on services.

To start an application on bootup with X11 instead change the x-session-manager. By default the system starts xfce:

root@ts:~# ls -lah /usr/bin/x-session-manager 
lrwxrwxrwx 1 root root 35 May 26  2015 /usr/bin/x-session-manager -> /etc/alternatives/x-session-manager
root@ts:~# ls -lah /etc/alternatives/x-session-manager
lrwxrwxrwx 1 root root 19 May 26  2015 /etc/alternatives/x-session-manager -> /usr/bin/startxfce4

The x-session can be modified to only start specified processes. Create the file /usr/bin/mini-x-session with these contents:

#!/bin/bash
matchbox-window-manager -use_titlebar no &

exec xfce4-terminal

You may need to "apt-get install matchbox-window-manager." first. This is a tiny window manager which also has a few flags that simplify embedded use. Now enable this session manager and restart slim to restart x11 and show it now.

chmod a+x /usr/bin/mini-x-session
rm /etc/alternatives/x-session-manager
ln -s /usr/bin/mini-x-session /etc/alternatives/x-session-manager
service slim restart

If the x-session-manager process ever closes x11 will restart. The exec command allows a new process to take over the existing PID. In the above example xfce4-terminal takes over the PID of x-session-manager. If the terminal is closed with commands like exit the slim/x11 processes will restart.

5 Backup / Restore

If you are using a Windows workstation there is no support for writing directly to block devices. However, as long as one of your booting methods still can boot a kernel and the initrd you can rewrite everything by using a usb drive. This is also a good way to blast many stock boards when moving your product into production. You can find more information about this method with an example script here.

Note: Note that the MBR installed by default on this board contains a 446 byte bootloader program that loads the initial power-on kernel and initrd from the first and second partitions. Replacing it with an MBR found on a PC would not work as a PC MBR contains an x86 code bootup program.

5.1 MicroSD Card

Note: This section is incomplete at this time.

TS-7682 MicroSD Backup

5.2 eMMC

Note: This section is incomplete at this time.

TS-7682 eMMC Backup

6 Software Development

Most of our examples are going to be in C, but Debian will include support for many more programming languages. Including (but not limited to) C++, PERL, PHP, SH, Java, BASIC, TCL, and Python. Most of the functionality from our software examples can be done from using system calls to run our userspace utilities. For higher performance, you will need to either use C/C++ or find functionally equivalent ways to perform the same actions as our examples. Our userspace applications are all designed to go through a TCP interface. By looking at the source for these applications, you can learn our protocol for communicating with the hardware interfaces in any language.

The most common method of development is directly on the SBC. Since debian has space available on the SD card, we include the build-essentials package which comes with everything you need to do C/C++ development on the board.


Editors

Vim is a very common editor to use in Linux. While it isn't the most intuitive at a first glance, you can run 'vimtutor' to get a ~30 minute instruction on how to use this editor. Once you get past the initial learning curve it can make you very productive. You can find the vim documentation here.

Emacs is another very common editor. Similar to vim, it is difficult to learn but rewarding in productivity. You can find documentation on emacs here.

Nano while not as commonly used for development is the easiest. It doesn't have as many features to assist in code development, but is much simpler to begin using right away. If you've used 'edit' on Windows/DOS, this will be very familiar. You can find nano documentation here.

Compilers

We only recommend the gnu compiler collection. There are many other commercial compilers which can also be used, but will not be supported by us. You can install gcc on most boards in Debian by simply running 'apt-get update && apt-get install build-essential'. This will include everything needed for standard development in c/c++.

You can find the gcc documentation here. You can find a simple hello world tutorial for c++ with gcc here.

Build tools

When developing your application typing out the compiler commands with all of your arguments would take forever. The most common way to handle these build systems is using a make file. This lets you define your project sources, libraries, linking, and desired targets. You can read more about makefiles here.

If you are building an application intended to be more portable than on this one system, you can also look into the automake tools which are intended to help make that easier. You can find an introduction to the autotools here.

Cmake is another alternative which generates a makefile. This is generally simpler than using automake, but is not as mature as the automake tools. You can find a tutorial here.

Debuggers

Linux has a few tools which are very helpful for debugging code. The first of which is gdb (part of the gnu compiler collection). This lets you run your code with breakpoints, get backgraces, step forward or backward, and pick apart memory while your application executes. You can find documentation on gdb here.

Strace will allow you to watch how your application interacts with the running kernel which can be useful for diagnostics. You can find the manual page here.

Ltrace will do the same thing with any generic library. You can find the manual page here.

6.1 Cross Compiling

Debian Jessie previously provided cross compilers via the Emdebian project. However, Emdebian has been unmaintained for a number of years and is no longer able to provide a viable install package. In order to cross compile from a Debian Jessie workstation, a third party cross compiler is required.

A Debian Jessie install on a workstation has the ability to build for the same release on other architectures using Debian binary libraries. A PC, virtual machine, or chroot will need to be used for this. Install Debian Jessie for your workstation here.

From a Debian workstation (not the target), run the following commands to set up the cross compiler. Note that this expects a 64-bit Debian Jessie install on the workstation. 32-bit installations are not supported at this time.

# Run "lsb_release -a" and verify Debian 8.X is returned.  These instructions are not
# expected to work on any other version or distribution.

cd ~
wget http://ftp.embeddedarm.com/ftp/ts-arm-sbc/ts-7680-linux/cross-toolchains/gcc-linaro-4.9-2016.02-x86_64_arm-linux-gnueabi.tar.xz
# The above toolchain is from Linaro. Other cross compilers can be used but have not been tested.
mkdir cross_compiler
tar xvf gcc-linaro-4.9-2016.02-x86_64_arm-linux-gnueabi.tar.xz -C ~/cross_compiler
export PATH=$PATH:~/cross_compiler/gcc-linaro-4.9-2016.02-x86_64_arm-linux-gnueabi/bin/
# The 'export' command needs to be run every time the user logs in. It is possible to add this command to the user's ".bashrc" file
# in their home directory to ensure it is automatically run every time the user is logged in.
su root
dpkg --add-architecture armel
apt-get update
apt-get install build-essential

This will install a toolchain that can be used with the prefix "arm-linux-gnueabi-". All of the standard GCC tools will start with that name, eg "arm-linux-gnueabi-gcc".

The toolchain can now compile a simple hello world application. Create hello-world.c on the Debian workstation:

#include <stdio.h>
int main(){
    printf("Hello World\n");
}

To compile this:

arm-linux-gnueabi-gcc hello-world.c -o hello-world
file hello-world

This will return that the binary created is for ARM. Copy this to the target platform to run it there.

Debian Jessie supports multiarch which can install packages designed for other architectures. On workstations this is how 32-bit and 64-bit support is provided. This can also be used to install armel packages on an x86 based workstation.

This cross compile environment can link to a shared library from the Debian root. The package would be installed in Debian on the workstation to provide headers and ".so" files. This is included in most "-dev" packages. When run on the arm target it will also need a copy of the library installed, but it does not need the -dev package. Note that since the cross compiler used is 3rd party and not directly from Debian, some compile commands that include libraries will need additional arguments to tell the compiler and linker where on the workstation to find the necessary headers and libraries. Usually, the additional arguments will look like the following string, however adjustments may need to be made depending on the application.

 -I/usr/include -L/usr/lib/arm-linux-gnueabi -L/lib/arm-linux-gnueabi -Wl,-rpath=/usr/lib/arm-linux-gnueabi,-rpath=/lib/arm-linux-gnueabi


apt-get install libcurl4-openssl-dev:armel

# Download the simple.c example from curl:
wget https://raw.githubusercontent.com/bagder/curl/master/docs/examples/simple.c
# After installing the supporting library, curl will link just as compiling on the unit.
arm-linux-gnueabi-gcc -I/usr/include -L/usr/lib/arm-linux-gnueabi -L/lib/arm-linux-gnueabi -Wl,-rpath=/usr/lib/arm-linux-gnueabi,-rpath=/lib/arm-linux-gnueabi simple.c -o simple -lcurl

The binary can now be copied over to the target platform and executed using the curl library that will be loaded at runtime from the target.

If any created binaries do not rely on hardware support like GPIO or CAN, they can be run using qemu.

# using the hello world example from before:
./hello-world
# Returns Exec format error
apt-get install qemu-user-static
./hello-world

6.2 Compile the Kernel

For adding new support to the kernel, or recompiling with more specific options you will need to have an x86 compatible Linux host available that can handle the cross compiling. Compiling the kernel on the board is not supported or recommended. Before building the kernel you will need to install a few support libraries on your workstation:

Prerequisites

All systems:

Download and unpack the cross compiler:

Note: The cross compiler set up in the Cross Compiling section is 64-bit and can be used instead of the 32-bit cross compiler below. If using the aforementioned compiler, it is not necessary to install the 32-bit compatibility libraries as is it for the 32-bit cross compiler on a 64-bit Debian Jessie installation.
wget ftp://ftp.embeddedarm.com/ts-arm-sbc/ts-7680-linux/cross-toolchains/imx28-cross-glibc.tar.bz2
tar xvf imx28-cross-glibc.tar.bz2 -C /path/to/folder/

/path/to/folder can be any directory so long as the current user has permissions to write to it. Remember this path as its used later during the kernel build procedure.


RHEL/Fedora/CentOS:

yum install ncurses-devel ncurses
yum groupinstall "Development Tools" "Development Libraries"


Ubuntu/Debian:

sudo apt-get install build-essential libncurses5-dev libncursesw5-dev git u-boot-tools


If you are on a 64-bit system, then 32-bit libraries will be required for the toolchain, for newer Debian and Ubuntu distrubutions with Multiarch support, use the command:

sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get install libc6-dev:i386 zlib1g-dev:i386

On older distributions:

sudo apt-get install ia32-libs


For other distributions, please refer to their documentation to find equivalent tools.


Download sources and configure

git clone https://github.com/embeddedarm/linux-3.14.28-imx28.git
cd linux-3.14.28-imx28/

# These next commands set up some necessary environment variables
export ARCH=arm
export CROSS_COMPILE=/path/to/folder/arm-fsl-linux-gnueabi/bin/arm-linux-
# If using the 64-bit cross compiler from the Cross Compiling section, the following CROSS_COMPILE variable can be
# used if the environment PATH is set up properly:
# export CROSS_COMPILE=arm-linux-gnueabi-
export LOADADDR=0x40008000

# This sets up the default configuration that we ship with
make ts76xx_defconfig

Once you have the configuration ready you can make your changes to the kernel. Commonly a reason for recompiling is to add support that was not built into the standard image's kernel. You can get a menu to browse available options by running:

make menuconfig

You can use the "/" key to search for specific terms through the kernel.

Build the kernel

Once you have it configured you can begin building the kernel. This usually takes about 5-10 minutes. This group of commands will also output a uImage file used by U-Boot on the TS-7680.

make && make uImage && make modules

We recommend running 'make' with the -jX argument, where X is the number of CPU cores+1 present on the build machine. This will greatly increase build speed.

Install the kernel/initramfs, headers, and modules

Next you need to install the kernel and modules to the SD card. We provide a simple script to copy the kernel uImage file, kernel modules, and headers to the SD card to update everything at once.

For example, if your workstation's SD card is /dev/mmcblk0:

./install_hdr_mod mmcblk0p2


If your workstation's SD card is /dev/sdc:

./install_hdr_mod sdc2

7 Features

7.1 Accelerometer

This SBC contains an NXP MMA8451 3-axis accelerometer. It is connected to the kernel as an input device and can be accessed through the input event layers. The kernel driver is only polling and the accelerometer's IRQs are not supported. The accelerometer supports a ±2, ±4, and ±8 g dynamically selectable scale.

On a stock system with no other peripherals attached, the accelerometer will show up as

 /dev/input/event0

If other peripherals, such as mice, keyboards, or other HID devices are attached at boot, then this device may change.

In order to read from the accelerometer it must first be enabled:

echo 1 > /sys/devices/virtual/input/input0/enable

The scale mode can be changed by writing a 0 (±2 g), 1 (±4 g), or 2 (±8 g) to the scalemode sys file:

#Set the scale mode to 8 g
echo 2 > /sys/devices/virtual/input/input0/scalemode

Note that the input0 above may change if other input devices are present in the system.


From here, a tool such as 'evtest' can be installed and run to verify output:

apt-get update
apt-get install evtest
evtest /dev/input/event0

The 'evtest' command will have output similar to the following:

 Event: time 1466445467.909559, -------------- EV_SYN ------------
 Event: time 1466445468.029557, type 3 (EV_ABS), code 0 (ABS_X), value -123
 Event: time 1466445468.029557, type 3 (EV_ABS), code 1 (ABS_Y), value -35
 Event: time 1466445468.029557, type 3 (EV_ABS), code 2 (ABS_Z), value 16294
 Event: time 1466445468.029557, -------------- EV_SYN ------------
 Event: time 1466445468.149557, type 3 (EV_ABS), code 1 (ABS_Y), value -17
 Event: time 1466445468.149557, type 3 (EV_ABS), code 2 (ABS_Z), value 16224
 Event: time 1466445468.149557, -------------- EV_SYN ------------
 Event: time 1466445468.269598, type 3 (EV_ABS), code 0 (ABS_X), value -149
 Event: time 1466445468.269598, -------------- EV_SYN ------------
 Event: time 1466445468.389560, type 3 (EV_ABS), code 1 (ABS_Y), value -48
 Event: time 1466445468.389560, type 3 (EV_ABS), code 2 (ABS_Z), value 16416
 

Readings from the accelerometer are read from the kernel input event interface. The linux documentation for the input system as well as event types are the best resource for creating an application to read from the device:

https://www.kernel.org/doc/Documentation/input/input.txt

https://www.kernel.org/doc/Documentation/input/event-codes.txt

Additionally, the Openmoko documentation has a great breakdown of the input event data:

http://wiki.openmoko.org/wiki/Accelerometer_data_retrieval#Data_structure

7.2 ADC

7.2.1 CPU

There are 4x 0-12 V Analog to Digital inputs on the TS-7682. They are in parallel with the LS outputs and the LS outputs must be disabled in order for the ADCs to function properly. These ADCs are from the i.MX28 CPU LRDAC, the Low-Resolution Analog to Digital Converter peripheral. The CPU peripheral is 12bit, 1.85 V input ADC with a 1.3% absolute error, with separate channels for single cycle acquisition of multiple inputs, and a maximum sample rate of 428 kHz.

Sample code to read the ADCs is provided by Technologic Systems, see mx28adcctl.c. This code can be used as-is, or integrated in to a C application. The code can also be translated in to other languages that allow for direct memory mapping and manipulation. The sample code will output the result of all 6 channels (only the first 4 channels are used on the TS-7682) and the HSADC peripheral (which is not used on the TS-7682) in its raw value after sampling each channel 10 times and averaging the results. Additionally, the sample code provides example math for converting the readings in to actual voltage or current readings.

For more information about the LRADCs, see the CPU manual

In order to use any of the four ADC channels, they must first be enabled as they are in parallel with the LS outputs. The LS output X for the respective channel must be deasserted, and the En. ADX must be asserted in order for ADC to work properly; where X is the LRADC channel number to be used. See the DIO section for more information on setting the mentioned pins.

ADC Chan. Location(s)
LRADC_ADC0 T_02
LRADC_ADC1 T_03
LRADC_ADC2 T_04
LRADC_ADC3 T_06

7.2.2 Microcontroller

The on-board microcontroller has 11 ADC channels that are used to monitor internal voltages. The internal ADC is a single-ended unipolar 10bit ADC with a 2.5 V full scale reference. The inputs can be queried with a call to tsmicroctl:

tsmicroctl -i

P1_2=0x3da
P1_3=0x3da
P1_4=0x3a8
P2_0=0x145
P2_1=0x3ab
P2_2=0x2ad
P2_3=0x2ed
P2_4=0x26c
P2_5=0x3d9
P2_6=0x2e7
P2_7=0x2b8


The PX_Y output are the various ADC channels, their inputs are the following:

Channel Input source Scale
P1_2 Super Cap balance output[1] 100%
P1_3 Super Cap tot. voltage[2] 50%
P1_4 Super Cap pre-boost voltage[3] 44.6%
P2_0 VIN 5.57%
P2_1 5 V Boost regulator output 44.6%
P2_2 Aux. 3.3 V 50%
P2_3 CPU 1.8 V 100%
P2_4 CPU Core 1.5 V 100%
P2_5 Super Cap charging voltage 50%
P2_6 RAM 1.8 V 100%
P2_7 CPU 3.3 V 50%
  1. The voltage of the second capacitor in the series of two
  2. Actual voltage of the series of Super Caps
  3. Actual voltage fed in to the boost regulator, diode drop below the total voltage

7.3 Battery Backed RTC

The TS-7682 implements a M41T00S STMicro Battery Backed RTC using an external and replaceable coin cell battery. This RTC is connected to the CPU via I2C and is handled by the kernel and is presented as a standard RTC device in linux.

7.4 Bluetooth

The WIFI option on the board also includes a bluetooth 4.0 LE module. To connect this to bluez first pulse the BT_EN pin, and then call hciattach:

echo 237 > /sys/class/gpio/export
echo low > /sys/class/gpio/gpio237/direction
echo high > /sys/class/gpio/gpio237/direction
sleep .1
hciattach /dev/ttyAPP0 texas 115200
hciconfig hci0 up

Once this is loaded you can scan for devices with:

hcitool scan

This will return a list of devices such as:

	14:74:11:A1:1E:C9	BlackBerry 8530

Bluez has support for many different profiles for HID, A2DP, and many more. Refer to the Bluez documentation for more information.

Please note that the Bluetooth module requires the modem control lines CTS and RTS as flow control.

7.5 CAN

The i.MX28 CPU has two FlexCAN ports that use the linux SocketCAN implementation. The ports can be set up and used with the following commands:

ip link set can0 up type can bitrate 1000000
ip link set can1 up type can bitrate 1000000


Note: The CAN_EN# signal is connected to CPU DIO 126 and is active low. The pin is de-asserted until the TS systemd script runs and asserts the enable bit. See the DIO section for more information.


At this point the ports can be used with standard SocketCAN libraries. In debian we provide cansend and candump to test the ports or as a simple packet send/recv tool. In order to test the two ports together, tie CAN_H of both CAN ports together, and do the same for CAN_L. Then use the following commands:

candump can0 &
cansend can1 7Df#03010c
#This command will return
  can0  7DF  [3] 03010c


The above example packet is designed to work with the Ozen Elektronik myOByDic 1610 ECU simulator to read the RPM speed. In this case, the ECU simulator would return data from candump with:

 <0x7e8> [8] 04 41 0c 60 40 00 00 00 
 <0x7e9> [8] 04 41 0c 60 40 00 00 00 

In the output above, columns 6 and 7 are the current RPM value. This shows a simple way to prove out the communication before moving to another language.

The following example sends the same packet and parses the same response in C:

#include <stdio.h>
#include <pthread.h>
#include <net/if.h>
#include <string.h>
#include <unistd.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <assert.h>
#include <linux/can.h>
#include <linux/can/raw.h>

int main(void)
{
	int s;
	int nbytes;
	struct sockaddr_can addr;
	struct can_frame frame;
	struct ifreq ifr;
	struct iovec iov;
	struct msghdr msg;
	char ctrlmsg[CMSG_SPACE(sizeof(struct timeval)) + CMSG_SPACE(sizeof(__u32))];
	char *ifname = "can0";
 
	if((s = socket(PF_CAN, SOCK_RAW, CAN_RAW)) < 0) {
		perror("Error while opening socket");
		return -1;
	}
 
	strcpy(ifr.ifr_name, ifname);
	ioctl(s, SIOCGIFINDEX, &ifr);
	addr.can_family  = AF_CAN;
	addr.can_ifindex = ifr.ifr_ifindex;
 
	if(bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
		perror("socket");
		return -2;
	}
 
 	/* For the ozen myOByDic 1610 this requests the RPM guage */
	frame.can_id  = 0x7df;
	frame.can_dlc = 3;
	frame.data[0] = 3;
	frame.data[1] = 1;
	frame.data[2] = 0x0c;
 
	nbytes = write(s, &frame, sizeof(struct can_frame));
	if(nbytes < 0) {
		perror("write");
		return -3;
	}

	iov.iov_base = &frame;
	msg.msg_name = &addr;
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_control = &ctrlmsg;
	iov.iov_len = sizeof(frame);
	msg.msg_namelen = sizeof(struct sockaddr_can);
	msg.msg_controllen = sizeof(ctrlmsg);  
	msg.msg_flags = 0;

	do {
		nbytes = recvmsg(s, &msg, 0);
		if (nbytes < 0) {
			perror("read");
			return -4;
		}

		if (nbytes < (int)sizeof(struct can_frame)) {
			fprintf(stderr, "read: incomplete CAN frame\n");
		}
	} while(nbytes == 0);

	if(frame.data[0] == 0x4)
		printf("RPM at %d of 255\n", frame.data[3]);
 
	return 0;
}

See the Kernel's CAN documentation here. Other languages have bindings to access CAN such as Python using C-types, Java using JNI.

7.6 CPU

This board features the i.MX286 454 MHz ARM9 from NXP. For more information about the processor and it's included peripherals, refer to the CPU manual.

7.7 DIO

The TS-7682 offers DIO, inputs, and low-side switches to accommodate nearly every application. The DIO exposed to various headers and terminals are controlled via the FPGA or CPU. All DIOs are controlled via the kernel sysfs interface. See the kernel's documentation here for more detail. The FPGA DIO pins all implement a crossbar switch and can be set to any combination of inputs and outputs. All DIO are 3.3 V tolerant unless otherwise noted. The low-side switches are able to sink 500 mA each with a maximum voltage input of 30 V (protected by a 30 V Zener diode). The low-side switches, when de-asserted, are high impedance inputs with a pullup resistor. A logical 0 input occurs from roughly 0 V to 1.5 V, while a logical 1 input occurs from roughly 1.6 V and higher on the low-side switches when in input mode.

To interact with DIO pins through the sysfs interface, it first must be exported to userspace, for example, DIO 237 is the BT_EN pin provided by the FPGA:

echo "237" > /sys/class/gpio/export

If you receive a permission denied on a pin that means it is claimed by another kernel driver. If it succeeds you will have a /sys/class/gpio/gpio237/ directory. The relevant files in this directory are:

 direction - "out" or "in"
 value - write "1" or "0", or read "1" or "0" if direction is in
 edge - write with "rising", "falling", or "none"
# Set GPIO 237 high
echo "out" > /sys/class/gpio/gpio237/direction
echo "1" > /sys/class/gpio/gpio237/value
# Set GPIO 237 low
echo "0" > /sys/class/gpio/gpio237/value

# Read the value of GPIO 237
echo "in" > /sys/class/gpio/gpio237/direction
cat /sys/class/gpio/gpio237/value

As an output, the in can be written to 0 for low (GND), or 1 for high (3.3V). As an input the GPIO will have a 100k pullup, note that DIO 39, 40, and 41 do NOT have internal pullups and instead have internal keeper functions from the i.MX28 CPU. It is also possible to use CPU GPIO (any DIO lower than DIO 192) as an interrupt by writing the edge value, and then using select() or poll() on the value file for changes.


DIO Function Location
39 DIO HD1_14
40 DIO HD1_09
41 DIO HD1_07
52 Input Push switch
59 En. USB 5 V N/A
73 Power fail N/A
126 En.# CAN N/A
192 LS output 0 T_02
193 LS output 1 T_03
194 LS output 2 T_04
195 LS output 3 T_06
196 LS output 4 T_07
197 LS output 5 T_08
198 LS input 0 T_02
199 LS input 1 T_03
200 LS input 2 T_04
201 LS input 3 T_06
202 LS input 4 T_07
203 LS input 5 T_08
210 En. relay N/A
211 MultiTech Reset# CN5_24
227 En. ADC 0 N/A
228 En. ADC 1 N/A
229 En. ADC 2 N/A
230 En. ADC 3 N/A
231 En. XBee 3.3 V[1] CN4_01
232 En. MT 5 V[1] CN5_61 / CN4_01[2] / CN4_06[2]
233 En. DC 5 V HD1_16 / HD1_15
237 En. BT N/A
  1. 1.0 1.1 Only enable one of these at a time. If both have the enable bits set, the FPGA will disable the output power for both.
  2. 2.0 2.1 Provides 4 V to XBee socket power, and 5 V to XBee V_USB for NimbeLink modems

7.7.1 LS Output

There are six Low Side switch outputs that can sink up to 500 mA at 30 VDC. There are a set of output only and input only registers for each LS switch. The input registers can be read at any time via the linux GPIO interface to see the actual logic present at the IO pin. Voltages about 1.3 V or lower are read as a 0, while anything higher, or the pin is left floating, will register as a 1. The output can be asserted via the linux GPIO interface; when they are asserted the switches provide a 500 mA current sink at a maximum of 30 VDC. Additionally, all input values can be read via a single FPGA register, 0xE. See the Syscon section for more information on this.

7.8 eMMC Interface

The i.MX28 SD card controller support the MMC specification. This SBC includes a soldered down eMMC IC to provide on-board flash media.

Our default software image contains 2 partitions:

Device Contents
/dev/mmcblk2 eMMC block device
/dev/mmcblk2p1 Unused
/dev/mmcblk2p2 Full Debian linux partition

This board includes a Micron eMMC module with builds that have "4096F" in the part number. Our off the shelf builds are 4GiB, but up to 64GiB are available for larger builds. The eMMC flash appears to Linux as an SD card at /dev/mmcblk2. Our default programming of the eMMC is the same as the SD card image.

The eMMC module has a similar concern by default to SD cards in that they should not be powered down during a write/erase cycle. However, this eMMC module includes support for setting a fuse for a "Write Reliability" mode, and a "psuedo SLC" mode. With both of these enabled then any writes will be atomic to 512B. If a sector is being written during a power loss, a block is guaranteed to have either the old or new data. Even in cases where the wrong data is present on the next boot, fsck is able to deal with the older data being present in a 512B block. The downsides to setting these modes are that it will about half the size of the eMMC module to 1.759Gib by default, and write speed will be slower.

The mmc-utils package is used to enable these modes.

WARNING: If you are using a custom built TS-7682 with an eMMC sized larger than 4GB, contact us before using these commands. The SLC partition will be specified different on larger disks.
mmc write_reliability set -n 0 /dev/mmcblk2
mmc enh_area set -y 0 1847296 /dev/mmcblk2
WARNING: Setting either of those modes is permanent and using the wrong value it is possible to essentially brick eMMC which will not be covered by the warranty. Evaluation units with fuses set will not be accepted through returns.

After this is run, reboot the board. On all future boots the eMMC will be detected at the smaller size.

7.9 External Reset

Note: Use caution when using the push switch as a hardware reset mechanism. Filesystem corruption can occur if proper precautions are not taken and a hardware reset occurs.


This SBC has a multi-purpose tactile button at a right angle to the PCB. This button can be used as a mechanism to issue a hardware reset to the SBC or as a way to wake up the device from its sleep modes (see Sleep for more information). Additionally, it can be set up as a generic input for user applications.

To enable or disable the hardware reset functionality:

tsmicroctl --resetswitchon  #Enable hardware reset
tsmicroctl --resetswitchoff #Disable hardware reset


To read the state of the input pin, see the DIO section for information on reading the Push Switch.

7.10 Ethernet

The i.MX28 processor implements a 10/100 ethernet controller with support built into the Linux kernel. The TS-7682 includes an integrated Marvell Ethernet switch that allows multiple interfaces from one 10/100 port. This allows a total bandwidth of 100MB/s between both ports.

EthSwitch.png

7.10.1 Switch

The default shipping configuration of the Marvell switch is to be in switch mode. This mode uses a single linux device, eth0, and the two ethernet jacks will transparently pass packets as a normal layer 2 ethernet switch. A DHCP client is normally started on the eth0 port.

Note: While in this mode, do not connect both ports to the same network subnet as this will have adverse effects on the operation of the TS-7682 and may cause issues on the network as well

7.10.2 VLAN

Additionally, the ethernet switch can have VLANs configured, one for each physical port. In this mode, linux will create eth0.1 and eth0.2 ports that are the actual VLAN ports. Routing and bridging can be set up on these ports as well if needed. DHCP clients are run on both of the ports by default. A number of systemd scripts are also implemented to correctly handle this mode. This includes systemd-network configuration to create and set up the VLAN ports, as well as a script to parse the eth0 MAC address, and set the eth0.1 and eth0.2 MAC addresses based on that address. In this mode, eth0 is not a valid interface port, only eth0.1 and eth0.2 ports are valid, however eth0 must remain up and active for proper operation.

To enable the VLAN mode, a change must be made to the kernel command line, add the switch "tsvlan" to it. The easiest way to do this is through U-Boot commands:

env set cmdline_append rw rootwait console=ttyAMA0,115200 loglevel=3 tsvlan
env save

7.10.3 Link status

The Marvell switch does not have a linux driver associated with it. Due to this, all of the configuration is handled from a userspace tool, switchctl. Because there is no proper driver, there is no way through the linux standard tools to query the actual link status of each port. The switchctl application can be used to do this:

switchctl --info

switch_model=88E6020
switch_ports="a b"
switchporta_link=1
switchporta_speed=100FD
switchportb_link=0
switchportb_speed=10HD
vtu_total=0

7.11 FPGA

The TS-7682 features an FPGA designed to accentuate the i.MX28 CPU peripherals with some additional peripherals and flexibility. The FPGA is connected to the CPU through an I2C bus.

See the Syscon section for more information about the FPGA register map.

7.11.1 FPGA Bitstreams

The FPGA has the capability to be reloaded on startup and reprogram itself with different configurations. The FPGA does have an internal configuration is stored, however the FPGA SRAM can be reloaded at bootup to provide an updated FPGA logic, or other custom implementations. U-Boot will automatically load the bitstream located at /boot/ts<model>-fpga.vme on the Debian root at startup.

The FPGA can be updated to the latest revision by booting to Debian and running:

cd /boot/
wget

The FPGA is loaded in to the FPGA SRAM on every poweron, so this file will need to exist for all future boots.


An FPGA revision changelog can be found in the Revisions and Changes section.

7.11.2 FPGA Programming

Currently, creating custom bitstreams is not supported. For more information contact Technologic Systems.

7.11.3 Crossbar

The FPGA includes a Crossbar mux. This allows nearly any output to be assigned any input. An input can be a physical pin, or the output of an FPGA peripheral such as the TXEN generator. Using the Crossbar, it is also possible to re-arrange UART port locations to put UARTs in various IO locations allowing for a large amount of flexibility of the SBC for a specific application.

A tool is provided for easy configuration of the Crossbar muxes. Using 'tshwctl' the current state of the Crossbar muxes can be read and written via environment variables:

root@imx28:~# tshwctl --get
DC_TXD=UART1_TXD
CELL_TXD=UART4_TXD
CELL_RTS=GPIO
RS_485_A_TXD=UART2_TXD
RS_485_A_TXEN=UART2_TXEN
RS_485_B_TXD=UART3_TXD
RS_485_B_TXEN=UART3_TXEN
BT_RXD=UART0_TXD
BT_CTS=UART0_RTS
UART0_RXD=BT_TXD
UART0_CTS=BT_RTS
UART1_RXD=DC_RXD
UART2_RXD=RS_485_A_RXD
UART3_RXD=RS_485_B_RXD
UART4_RXD=CELL_RXD

In order to change any of the above assignments, use the named environment variables. For example, to set UART4 to the pins for the daughtercard interface, the following commands can be used:

root@imx28:~# export DC_TXD=UART4_TXD
root@imx28:~# export UART4_RXD=DC_RXD
root@imx28:~# export CELL_TXD=GPIO  #This is used to prevent the COM2 port from transmitting the data that is sent on UART4
root@imx28:~# tshwctl --set
root@imx28:~# tshwctl --get
...
DC_TXD=UART4_TXD
...
CELL_TXD=GPIO
...
UART4_RXD=DC_RXD
...

At this point, /dev/ttyAPP4 will now transmit and receive on the DC_TXD and DC_RXD pins.


Available outputs:

Output name Location Default input
DC_TXD HD1_12 UART1_TXD
CELL_TXD CN5_35 UART4_TXD
CELL_RTS CN5_33 GPIO
RS_485_A_TXD U28 pin 4 UART2_TXD
RS_485_A_TXEN U28 pin 2 & 3 UART2_TXEN
RS_485_B_TXD U29 pin 4 UART3_TXD
RS_485_B_TXEN U29 pin 2 & 3 UART3_TXEN
BT_RXD K5 pin 34 UART0_TXD
BT_CTS K5 pin 39 UART0_RTS
UART0_RXD U7 pin B8 BT_TXD
UART0_CTS U7 pin P4 BT_RTS
UART1_RXD U7 pin M9 DC_RXD
UART2_RXD U7 pin N2 RS_485_A_RXD
UART3_RXD U7 pin J1 RS_485_B_RXD
UART4_RXD U7 pin H2 CELL_RXD


Available input assignments:

Input name Location
UNCHANGED N/A
DC_RXD HD1_10
CELL_RXD CN5_34
CELL_CTS CN5_38
RS_485_A_RXD U28 pin 1
RS_485_B_RXD U29 pin 1
BT_TXD K5 pin 36
BT_RTS K5 pin 35
UART0_TXD U7 pin J2
UART0_TXEN N/A
UART0_RTS U7 pin A2
UART1_TXD U7 pin N5
UART1_TXEN N/A
UART2_TXD U7 pin F1
UART2_TXEN N/A
UART3_TXD U7 pin M2
UART3_TXEN N/A
UART4_TXD U7 pin K1
UART4_TXEN N/A
GPIO N/A
DIO_IN_0 T_02
DIO_IN_1 T_03
DIO_IN_2 T_04
DIO_IN_3 T_06
DIO_IN_4 T_07
DIO_IN_5 T_08


7.11.4 Syscon

All of the registers below are 8 bits wide and are accessed through the I2C interface. The FPGA is located at 7 bit address 0x28 on the linux device /dev/i2c-0. Accessing registers can either be done directly via tshwctl with the --peek and --poke options, using tshwctl options to abstract some of the access details away, or directly accessing and manipulating the linux I2C device. See the tshwctl sources for an example of how this is implemented

Offset GPIO # Bits Usage [Initial value/MUX]
0x0
192 7:2 Reserved
1 EN. LS_OUT_0 value [0] (RW)
0 Reserved
0x1
193 7:2 Reserved
1 EN. LS_OUT_1 value [0] (RW)
0 Reserved
0x2
194 7:2 Reserved
1 EN. LS_OUT_2 value [0] (RW)
0 Reserved
0x3
195 7:2 Reserved
1 EN. LS_OUT_3 value [0] (RW)
0 Reserved
0x4
196 7:2 Reserved
1 EN. LS_OUT_4 value [0] (RW)
0 Reserved
0x5
197 7:2 Reserved
1 EN. LS_OUT_5 value [0] (RW)
0 Reserved
0x6
198 7:2 Reserved
1 DIO_IN_0 value [0] (RW)
0 Reserved
0x7
199 7:2 Reserved
1 DIO_IN_1 value [0] (RW)
0 Reserved
0x8
200 7:2 Reserved
1 DIO_IN_2 value [0] (RW)
0 Reserved
0x9
201 7:2 Reserved
1 DIO_IN_3 value [0] (RW)
0 Reserved
0xA
202 7:2 Reserved
1 DIO_IN_4 value [0] (RW)
0 Reserved
0xB
203 7:2 Reserved
1 DIO_IN_5 value [0] (RW)
0 Reserved
0xC N/A N/A Reserved
0xD N/A N/A Reserved
0xE
N/A 7:6 Reserved
5 DIO_IN_5 (RO)
4 DIO_IN_4 (RO)
3 DIO_IN_3 (RO)
2 DIO_IN_2 (RO)
1 DIO_IN_1 (RO)
0 DIO_IN_0 (RO)
0xF N/A N/A Reserved
0x10 N/A N/A Reserved
0x11 N/A N/A Reserved
0x12
210 7:2 Reserved
1 Enable Relay 1 [0] (RW)
0 Reserved
0x13
211 7:2 Reserved
1 MultiTech Reset# [0] (RW)
0 Reserved
0x14
N/A 7:2 DC TXD Crossbar [UART1_TXD] (RW)
1 DC TXD value [0] (RW)
0 Reserved
0x15
N/A 7:2 CELL TXD Crossbar [UART4_TXD] (RW)
1 CELL TXD value [0] (RW)
0 Reserved
0x16
214 7:2 CELL RTS Crossbar [GPIO] (RW)
1 CELL RTS value [0] (RW)
0 Reserved
0x17
N/A 7:2 RS-485 A TXD Crossbar [UART2_TXD] (RW)
1 RS-485 A TXD value [0] (RW)
0 Reserved
0x18
N/A 7:2 RS-485 A TXEN Crossbar [UART2_TXEN] (RW)
1 RS-485 A TXEN value [0] (RW)
0 Reserved
0x19
N/A 7:2 RS-485 B TXD Crossbar [UART3_TXD] (RW)
1 RS-485 B TXD value [0] (RW)
0 Reserved
0x1A
N/A 7:2 RS-485 B TXEN Crossbar [UART3_TXEN] (RW)
1 RS-485 B TXEN value [0] (RW)
0 Reserved
0x1B
N/A 7:2 Bluetooth RXD Crossbar [UART0_TXD] (RW)
1 Bluetooth RXD value [0] (RW)
0 Reserved
0x1C
N/A 7:2 Bluetooth CTS Crossbar [UART0_RTS] (RW)
1 Bluetooth CTS value [0] (RW)
0 Reserved
0x1D
N/A 7:2 UART0 RXD Crossbar [BT_TXD] (RW)
1 UART0 RXD value [0] (RW)
0 Reserved
0x1E
N/A 7:2 UART0 CTS Crossbar [BT_RTS] (RW)
1 UART0 CTS value [0] (RW)
0 Reserved
0x1F
N/A 7:2 UART1 RXD Crossbar [DC_RXD] (RW)
1 UART1 RXD value [0] (RW)
0 Reserved
0x20
N/A 7:2 UART2 RXD Crossbar [RS_485_A_RXD] (RW)
1 UART2 RXD value [0] (RW)
0 Reserved
0x21
N/A 7:2 UART3 RXD Crossbar [RS_485_B_RXD] (RW)
1 UART3 RXD value [0] (RW)
0 Reserved
0x22
N/A 7:2 UART4 RXD Crossbar [CELL_RXD] (RW)
1 UART4 RXD value [0] (RW)
0 Reserved
0x23
227 7:2 Reserved
1 En. AD0 [0] (RW)
0 Reserved
0x24
228 7:2 Reserved
1 En. AD1 [0] (RW)
0 Reserved
0x25
229 7:2 Reserved
1 En. AD2 [0] (RW)
0 Reserved
0x26
230 7:2 Reserved
1 En. AD3 [0] (RW)
0 Reserved
0x27
231 7:2 Reserved
1 En. XBee 3.3 V [0] (RW)
0 Reserved
0x28
232 7:2 Reserved
1 En. MultiTech 5 V [1] (RW)
0 Reserved
0x29
233 7:2 Reserved
1 En. DC header 5 V [1] (RW)
0 Reserved
0x2A
N/A 7:3 Reserved
2 Disable SPI interface (en. UART2 & 3) [0] (RW)
1 Boot SPI select; 0: offbd, 1: onbd [0] (RW)
0 Override automatic Boot SPI select [0] (RW)
0x2B
235 7:2 Reserved
1 Ethernet reset# [0] (RW)
0 Reserved
0x2C
236 7:2 Reserved
1 WLAN En. [0] (RW)
0 Reserved
0x2D
237 7:2 Reserved
1 Bluetooth En. [0] (RW)
0 Reserved
0x2E N/A N/A Reserved
0x2F N/A N/A Reserved
0x30 N/A N/A Reserved
0x31 N/A N/A Reserved
0x32 N/A N/A Reserved
0x33 N/A N/A Reserved
0x34 N/A N/A Reserved
0x35 N/A N/A Reserved
0x36 N/A 7:0 Bits 23:16 of auto-485 #0 counter #0 [0] (RW)[1][2]
0x37 N/A 7:0 Bits 15:8 of auto-485 #0 counter #0 [0] (RW)[1][2]
0x38 N/A 7:0 Bits 7:0 of auto-485 #0 counter #0 [0] (RW)[2]
0x39 N/A 7:0 Bits 23:16 of auto-485 #0 counter #1 [0] (RW)[1][3]
0x3A N/A 7:0 Bits 15:8 of auto-485 #0 counter #1 [0] (RW)[1][3]
0x3B N/A 7:0 Bits 7:0 of auto-485 #0 counter #1 [0] (RW)[3]
0x3C N/A 7:0 Bits 23:16 of auto-485 #1 counter #0 [0] (RW)[1][2]
0x3D N/A 7:0 Bits 15:8 of auto-485 #1 counter #0 [0] (RW)[1][2]
0x3E N/A 7:0 Bits 7:0 of auto-485 #1 counter #0 [0] (RW)[2]
0x3F N/A 7:0 Bits 23:16 of auto-485 #1 counter #1 [0] (RW)[1][3]
0x40 N/A 7:0 Bits 15:8 of auto-485 #1 counter #1 [0] (RW)[1][3]
0x41 N/A 7:0 Bits 7:0 of auto-485 #1 counter #1 [0] (RW)[3]
0x42 N/A 7:0 Bits 23:16 of auto-485 #2 counter #0 [0] (RW)[1][2]
0x43 N/A 7:0 Bits 15:8 of auto-485 #2 counter #0 [0] (RW)[1][2]
0x44 N/A 7:0 Bits 7:0 of auto-485 #2 counter #0 [0] (RW)[2]
0x45 N/A 7:0 Bits 23:16 of auto-485 #2 counter #1 [0] (RW)[1][3]
0x46 N/A 7:0 Bits 15:8 of auto-485 #2 counter #1 [0] (RW)[1][3]
0x47 N/A 7:0 Bits 7:0 of auto-485 #2 counter #1 [0] (RW)[3]
0x48 N/A 7:0 Bits 23:16 of auto-485 #3 counter #0 [0] (RW)[1][2]
0x49 N/A 7:0 Bits 15:8 of auto-485 #3 counter #0 [0] (RW)[1][2]
0x4A N/A 7:0 Bits 7:0 of auto-485 #3 counter #0 [0] (RW)[2]
0x4B N/A 7:0 Bits 23:16 of auto-485 #3 counter #1 [0] (RW)[1][3]
0x4C N/A 7:0 Bits 15:8 of auto-485 #3 counter #1 [0] (RW)[1][3]
0x4D N/A 7:0 Bits 7:0 of auto-485 #3 counter #1 [0] (RW)[3]
0x4E N/A 7:0 Bits 23:16 of auto-485 #4 counter #0 [0] (RW)[1][2]
0x4F N/A 7:0 Bits 15:8 of auto-485 #4 counter #0 [0] (RW)[1][2]
0x50 N/A 7:0 Bits 7:0 of auto-485 #4 counter #0 [0] (RW)[2]
0x51 N/A 7:0 Bits 23:16 of auto-485 #4 counter #1 [0] (RW)[1][3]
0x52 N/A 7:0 Bits 15:8 of auto-485 #4 counter #1 [0] (RW)[1][3]
0x53 N/A 7:0 Bits 7:0 of auto-485 #4 counter #1 [0] (RW)[3]
0x7D N/A 7:0 Board ID, reads 0x82
0x7E
NA 7:3 Reserved
2 WiFi Module present
1:0 Reserved
0x7F NA 7:0 FPGA Revision
  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 MUST be written before bits 7:0
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 Value of counter #0 must be set to count to the mid-point of the stop bit based on a 25MHz clock
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 Value of counter #1 must be set to count to one-half bit time based on a 25MHz clock

7.12 I2C

The i.MX28 CPU I2C pins are not exposed to any external interfaces on this SBC. Because of this, bitbanging is strongly recommended for any attached peripherals that would utilize I2C.

Technologic Systems recommends using direct bitbanging of I2C pins from userspace to drive an I2C interface. See the DIO section for further information on manipulating DIO pins.

Another option is to implement i2c-gpio in linux. This allows for an I2C physical interface on GPIO pins, but uses the kernel I2C software interface to read and write data on the I2C bus. See linux kernel documentation and i2c-dev for more information on this.

7.13 Jumpers

The TS-7682 has a set of jumpers located between the LEDs and the WiFi/BT module. These jumpers control a number of aspects of the TS-7682's behavior. The jumpers are labeled on the silkscreen rather than numbered:

Label Description
SD When jumper is set, boot kernel and Debian from the SD card. Otherwise boot kernel and Debian from eMMC
UBoot When jumper is set, pause booting in U-Boot and drop to a U-Boot shell. Otherwise booth straight to Debian.
CAN When jumper is set, adds a 120 ohm termination resistor across CAN0 H and L pins. (Note: the CAN1 interface always has a 120 ohm termination)
485 When jumper is set, adds a 120 ohm termination resistor across RS-485 + and - pins. (Note: this is for the RS-485 port, the MODBUS port always has a 120 ohm termination)
NO CHRG When jumper is set, disable charging of the SuperCaps. Beneficial for early development and testing.

7.14 LEDs

On all of our SBCs we include 2 indicator LEDs which are under software control. You can manipulate these using the linux GPIO interface. The LEDs have 4 behaviors from default software.

Green Behavior Red behavior Meaning
Solid On Off System is booted and running
Solid On On for approximately 20s, then off The red LED will remain on from power on until Debian has finished booting. The first boot of the unit will have the LED on longer as part of this process is generating SSH keys for the unit.
On for 10s, off for 100ms, and repeating On for 10s, off for 100ms, and repeating The watchdog is continuously resetting the board. This happens when the system cannot find a valid boot device, or the watchdog is otherwise not being fed. This is normally fed by the kernel once a valid boot media has started. See the #Watchdog section for more details.
Off Off The SBC is not able to boot. Typically either the board is not being supplied with enough voltage, or the SBC has been otherwise damaged. If a stable voltage is being provided and the supply is capable of providing at least 1A to the SBC, an RMA is suggested.
Blinking about 5ms on, about 10ms off. Blinking about 5ms on, about 10ms off. The board is receiving too little power, or something is drawing too much current from the unit's power rails.


Linux GPIO LED control:

LED DIO
Red# 7
Green# 5
Yellow# 58
Blue 56

7.15 MicroSD Card Interface

The i.MX6ul SD card controller is used for the SD card present on the board which supports the SD and SDHC specifications. This controller has been tested with Sandisk Extreme SD cards which allow read speeds up to 20.5MB/s, and write speeds up to 21.5MB/s.

Our default software image contains a single partition:

Device Contents
/dev/mmcblk0 SD Card block device
/dev/mmcblk0p1 Full Debian linux partition

7.16 Reboot Source

The supervisory microcontroller is capable of saving and displaying the reason for the most recent reboot. This can be used to detect various errors that may occur in the field, as well as simple accounting of events. The source can be queried with tsmicroctl:

tsmicroctl -i

reboot_source=poweron


Possible sources and causes are:

Source Possible causes
poweron Power removed, Super Caps discharged, and then power applied
brownout Like "poweron," however the SuperCaps have not fully discharged
WDT WDT timeout; reboot command (which reboots via WDT)
resetswitch The reset switch has been enabled and has been asserted
sleep The system has woken up from a sleep command

7.17 Relays

The TS-7682 features 1 SPDT relay rated for 5A at 277VAC or 30VDC that the user can toggle through an FPGA register. The PCH-105D2H relay closes in 10ms, and opens in 5ms. A very safe assumption would be that it will switch after 20ms. The common, NO (Normally Open), and NC (Normally Closed) connections are brought out to multiple points. See the DIO section of the manual for information on manipulating the relays.

Contact Location
COM T_10
NO T_12
NC T_11

7.18 Sleep

Note: As soon as the sleep command is issued the unit will go to sleep. If the proper precautions are not taken, filesystem corruption can result as the sleep mode removes all power from the CPU and other peripherals on the SBC


The addition of a microcontroller on board this SBC allows it to play a supervisory role over the CPU.

Low power sleep mode will remove power from all of the rails, turning off the CPU and every other peripheral save for the microcontroller. This mode offers extreme power savings, only requiring around 90 mW of power, with the ability to wake up after an arbitrary timeout (up to 1847297s, which is 21d 9h 8m 17s) with a 1s resolution. In order to enter this mode, issue the following command:

tsmicroctl --sleep --timewkup <time in seconds> --resetswitchwkup

Waking up from a sleep will take roughly 4-5s from when the timer expires or when the reset button is pressed. This is normal bootup time for the CPU.

Note that both --timewkup and --resetswitchwkup are optional arguments, you can pass none, one, or both. If no arguments are passed then the SBC will remain in sleep mode forever, until power is removed completely and re-applied. This can be useful instead of halting in linux as sleeping would consume far less power than simply halting the CPU. Be aware however, that if the Super Caps are installed they will keep power to the on-board microcontroller for a very long time. If the Super Caps are used than an external wakeup via timer or reset switch is highly recommended.

7.19 SPI

This SBC utilizes all of the i.MX28 CPU SPI ports for the SD cards, therefore there is no externally available SPI peripheral from the CPU. Because of this, bitbanging is strongly recommended for any attached peripherals that would utilize SPI.

Technologic Systems recommends using direct bitbanging of SPI pins from userspace to drive an SPI interface. See the DIO section for further information on manipulating DIO pins.

Another option is to implement spi-gpio in linux. This allows for a SPI physical interface on GPIO pins, but uses the kernel SPI software interface to read and write data on the SPI bus. See linux kernel documentation, spi-gpio, and spidev for more information on this.

7.20 SuperCaps

The TS-7682 has an option to add two 2.7 V 25 F supercapacitors. These two SuperCaps can provide up to 20 seconds of power hold time automatically if the external power input is removed. The Power Fail input signal (see the DIO Section) can be used to determine if the exterior power has been removed or fallen below a valid input level. Using this signal, a proper shutdown can be issued to ensure that all data is flushed from cache to disk, and all disks are unmounted properly.

The SuperCaps charge and discharge is managed transparently by the supervisory microcontroller. A jumper is provided on Rev. C and later PCBs to disable the charging and use of the SuperCaps. This mode is very useful for development to allow for proper power-off conditions without having to wait for the SuperCaps to discharge. The supervisory microcontroller will also not allow the TS-7682 to boot if power input is invalid. If the system reboots safely due to a power failure, it will remain in a powered off state until external power is re-applied, or the SuperCaps discharge below the sustainable threshold. Note that it is required to have at least 8.5 VDC input when charging completely flat supercapacitors, otherwise the TS-7682 will not power on properly due to the voltage brownout experienced from the supercapacitor charging.

By default, a script is started with systemd to monitor the Power Fail pin, and present all logged in users with a message saying that the power has failed and a graceful shutdown is taking place if the power input has failed. This script is located at /usr/local/bin/tssupercapmon

Additionally, U-Boot can delay booting until the SuperCaps are charged to a certain percentage, and optionally print the current percentage once per second. These are controlled with the environment variables "chrg_pct" and "chrg_verb" By setting chrg_pct to anything other than 0 (0 means do not wait, which is the default behavior), booting will be delayed until that percentage is reached. Setting chrg_verb to 1 will enable the verbose printing of the current percentage every second. Note that the SuperCaps may be at "0%" for a large period of time, this is due to the charge level being below a voltage that can sustain the TS-7682. See the U-Boot section for information on setting environment variables.

A recommended starting point is 60%. This value was chosen because it can ensure the system is powered long enough to boot up and safely shut down (and provide an additional 10 s of power) if power is immediately cut once booting has started. Please note that this only applies to the default stock image, any further changes to the TS-7682 hardware or software, such as connecting powered devices like USB or adding additional applications may cause the recommended value to not sustain the TS-7682 until a safe shutdown is completed. The time it takes to reach 60% charge will vary depending on the current charge of the SuperCaps. On average, it will take about 20 seconds to charge the SuperCaps to 60%; this is assuming the SuperCaps have very recently fallen below the threshold voltage to sustain the TS-7682.

7.21 Temperature Sensor

The on-board supervisory microcontroller contains an internal temperature sensor that can measure near ambient temperature on the SBC. The temperature sensor shares the same charastics of the ADC, that is, 10 bit with a 2.5 V reference voltage. The current value of the temperature sensor can be read with tsmicroctl:

tsmicroctl -i

...
temp_sensor=0x160
...

The temperature sensor has a 2.87 mV/°C slope, with an offset of 764 mV at 0 °C. The final output has a linearity of ±0.5 °C, an output error of ±128 uV/°C, and an offset error of ±15 mV.

Note that the actual temperature will be higher than true ambient. This is due to internal die heating, as well as overall heating of the PCB from operation.

7.22 UARTs

All of these UARTs are accessed using the standard /dev/ interfaces. See these resources for information on programming with UARTs in Linux.

All 5 of the CPU UARTs are run through the FPGA through the Crossbar mux to control where they go. The mux allows for extreme flexibility in use of UARTs and how they are set up. The table below lists the CPU UARTs with their default assignment and those default pin locations. The subsections list and describe the various external interfaces, including RS-232 and RS-485, any extra set up configurations, and their Crossbar mux input names.

Name Mux output Mux input Def. Assign. Def. Type Def. TX / + Def. RX / -
ttyAPP0[1] UART0_TXD UART0_RXD Bluetooth TTL N/A N/A
ttyAPP1 UART1_TXD UART1_RXD DC TTL HD1_12 HD1_10
ttyAPP2 UART2_TXD UART2_RXD RS-485 A RS-485 J6_4 J6_5
ttyAPP3 UART3_TXD UART3_RXD RS-485 B RS-485 J4_4 J4_5
ttyAPP4 UART4_TXD UART4_RXD Cell modem TTL CN5_35 CN5_34
  1. Also brings out CTS and RTS as UART0_CTS and UART0_RTS Crossbar mux names.


7.22.1 RS-485

The TS-7682 offers two RS-485 ports. These ports default to CPU UART 2 and 3. The half-duplex transmit-enable is handled by the FPGA having two sets of values per-port to control the timing of the TXEN line. There are a total of 5 auto-TXEN blocks, each one is assigned to a UART. In order to set up these registers, the following command must be issued before the TXEN will function properly:

tshwctl --autotxen <uart number> --baud <baud>

Additionally, different modes can be passed to the command to adjust for the number of bits, for example:

tshwctl --autotxen <uart number> --baud <baud> --mode 8n1  #Default, 8n1 mode, 8 data bits, no parity, 1 stop bit
tshwctl --autotxen <uart number> --baud <baud> --mode 7e2  #7e2 mode, 7 data bits, even parity, 2 stop bits

Note that the baud and mode actually used on the UART must match what is passed to tshwctl. Any differences will cause TXEN to be released too soon or held too long and cause unexpected issues on the bus. If the mode or baud rate of the UART is changed, the tshwctl commands must be re-issued with the new settings.

The RS-485 ports are available on the following external connectors and Crossbar mux settings:

Name Mux output Mux input + location - location
RS-485 A RS_485_A_TXD RS_485_A_RXD J6_4 J6_5
RS-485 B RS_485_B_TXD RS_485_B_RXD J4_4 J4_5


7.22.1.1 MODBUS power

The J6 and J4 connectors are set up for a standard 2W-MODBUS pinout that provides power. The voltage output is VIN minus a diode drop. The power can be enabled with the following command:

tshwctl --modbuspoweron
#Will return
modbuspoweron=1

The power on sequence will first apply 3 V, verify there is no short on the bus, and then apply the full voltage. If the command returns 'modbuspoweron=0' then that means there is a detected short on the other side of the bus due to mis-wiring or incorrect connection on the other side. The power can be turned off with:

tshwctl --modbuspoweroff

7.22.2 Misc. Ports

The TS-7682 has a 1.8 V TTL UART Bluetooth interface, and a pair of pins on a header dedicated to connect to a Daughter Card with a TTL UART connection. Additionally, with the Crossbar mux, nearly any IO pin can be set up to act as TX or RX for each of the UARTs.

The following table lists information about these two interfaces:

Name Mux output Mux input TX location RX location
Bluetooth[1] BT_RXD BT_TXD N/A N/A
Daughter Card DC_TXD DC_RXD HD1_12 HD1_10
  1. Note, the Bluetooth modules requires the control lines CTS and RTS, their Crossbar mux names are BT_CTS and BT_RTS

7.23 USB

The USB host port is a standard USB 2.0 at 480Mbps. The Linux kernel provides most of the USB support, and some devices may require a kernel recompile. For creating custom USB support, libusb may be the easiest route.

USB 5V Power can be disabled or re-enabled using DIO 69, marked EN_USB_5V on the schematic. See the syscon for more information on using this bit.

See the WIFI-N-USB manual for information on our WIFI support.

7.24 Watchdog

This SBC implements a Watch Dog Timer in a microcontroller on the SBC. An external WDT allows for high assurance operation of the WDT, as it uses external hardware, kernel level software, and userspace level software. If any of the three fail then the WDT will timeout and reboot the whole system. A standard kernel WDT driver is in place. As soon as the kernel starts it will start the WDT and feed it on 30 second timeouts every 15 seconds. If a userspace application opens and uses the watchdog file, the kernel will stop auto-feeding and the user application is now responsible for feeding the WDT. The kernel driver supports the "Magic Close" feature of the WDT. This means that a 'V' character must be fed in to the watchdog file before the file is closed in order to disable the WDT. Additionally, if the kernel is compiled with CONFIG_WATCHDOG_NOWAYOUT then the WDT can never be stopped once it is started at boot.

See the Linux WDT API documentation for more information.

7.25 Wi-Fi

This SBC includes a TiWi-BLE SDIO module that uses the Texas Instruments WL1271L Transceiver. Linux provides support for this using the wl12xx driver. See the LSR site for detailed product information.

Summary Features:

  • IEEE 802.11 b/g/n
  • 2.4GHz
  • Linux drivers include support for client and AP mode
  • Industrial temp, -40 to 85C
  • Certifications
    • FCC Bluetooth® Grant
    • FCC WLAN Grant
    • IC
    • CE
    • SAR Testing
    • SAR Testing EU

Linux uses the "wireless-tools", "wpa-supplicant", and "hostapd" packages to support most of the functionality in this module. Refer to the distribution support for more information.

See the Network Configuration section for information on setup and configuring the WiFi device.

8 External Interfaces

8.1 HD1 Pin Header

Pin Name
HD1_1 VIN
HD1_2 POE_78
HD1_3 GND
HD1_4 POE_45
HD1_5 GND
HD1_6 POE_TX
HD1_7 DIO 41
HD1_8 POE_RX
HD1_9 DIO 40
HD1_10 DC_RXD [1]
HD1_11 USB OTG -
HD1_12 DC_TXD
HD1_13 USB OTG +
HD1_14 DIO 39
HD1_15 5 V (En. DIO 233)
HD1_16 5 V (En. DIO 233)
Pin Layout
1 2
3 4
5 6
7 8
9 10
11 12
13 14
15 16
  1. 5V tolerant input

8.2 12 pos. Screw Terminal

7682-pinout.png

Terminal
Pin Name
T_01 GND
T_02 LS output 0 / AD0
T_03 LS output 1 / AD1
T_04 LS output 2 / AD2
T_05 GND
T_06 LS output 3 / AD3
T_07 LS output 4
T_08 LS output 5
T_09 GND
T_10 Relay Com.
T_11 Relay NC
T_12 Relay NO

8.3 J4 RJ-45

RJ45single.svg

Pin Name
J4_1 CAN0_H
J4_2 CAN0_L
J4_3 GND
J4_4 RS-485 B D+
J4_5 RS-485 B D-
J4_6 J1939 Shield
J4_7 MODBUS V+
J4_8 GND

8.4 J6 RJ-45

RJ45single.svg

Pin Name
J4_1 CAN1_H
J4_2 CAN1_L
J4_3 GND
J4_4 RS-485 A D+
J4_5 RS-485 A D-
J4_6 J1939 Shield
J4_7 MODBUS V+
J4_8 GND

8.5 CN4 XBee

The CN4 socket is compatible with both XBee radios as well as the NimbeLink socket cell modems. This connector is mechanically locked out with CN5 so only one socket can be used at a time.

XBeesingle.png

Pin Name
1 VCC[1]
2 CELL_RXD
3 CELL_TXD
4 GND
5 NC
6 5 V[2]
7 USB DP
8 USB DM
9 GND
10 GND
11 GND
12 NC
13 NC
14 3.3 V
15 GND
16 GND
17 NC
18 NC
19 NC
20 GND
  1. This pin will provide 3.3 V or 4 V depending on if "XBee 3.3 V" or "MT 5 V" is enabled. See the DIO section for more information.
  2. Enabled with "MT 5 V". See the DIO section for more information.

8.6 CN5 MultiTech

Pin 32 and 33 are near the power connector, while pin 1 and pin 64 are near the terminal connector.

Multitech-universal socket cell.png

Note: Only populated pins are listed below
Pin Name
24 MultiTech Reset#
25 MT 5 V
26 GND
27 USB D+
28 USB D-
33 CELL_RTS
34 CELL_RXD
35 CELL_TXD
36 NC
37 NC
38 CELL_CTS
39 NC
40 GND[1]
41 GND
59 NC
60 NC
61 MT 5 V
62 NC
63 GND

9 Revisions and Changes

9.1 Microcontroller Changelog

Revision Changelog
0x0
  • Initial release
0x1
  • Read VIN to turn on CPU at 7.5V and turn off at 7V
  • Bugfix where ADC was being overdriven, resulting in improper results
0x2
  • Disabled WDT on bootup, needed for U-Boot at this time.
0x3
  • Transfer to SiLabs 8051 microcontroller
  • Updates for TS-7680 Rev. B PCB
  • Added support for Supercapacitor charging and discharging
0x4
  • Set up proper sleep mode
0x5
  • Support for Rev C PCB
  • Added support for NO CHRG jumper to prevent SuperCap charging.
0x6
  • Not publicly released
0x7
  • Added a bit to read the NO CHRG jumper status
  • TS-7682 first released with this revision, directly compatible with the TS-7680

9.2 FPGA Changelog

Revision Changelog
0x0
  • Initial release
0x1
  • Added support for 4th strapping resistor for build options

9.3 PCB Revisions

Revision Changelog
A
  • Initial release

9.4 Software Images

Image File Changelog Known Issues
ts768x-dec052016.dd.bz2

ts768x-dec052016.tar.bz2

  • First official Engineering sample image release

9.5 U-Boot

Revision Changelog
December 7th, 2016
  • Initial release.

10 Product Notes

10.1 FCC Advisory

This equipment generates, uses, and can radiate radio frequency energy and if not installed and used properly (that is, in strict accordance with the manufacturer's instructions), may cause interference to radio and television reception. It has been type tested and found to comply with the limits for a Class A digital device in accordance with the specifications in Part 15 of FCC Rules, which are designed to provide reasonable protection against such interference when operated in a commercial environment. Operation of this equipment in a residential area is likely to cause interference, in which case the owner will be required to correct the interference at his own expense.

If this equipment does cause interference, which can be determined by turning the unit on and off, the user is encouraged to try the following measures to correct the interference:

Reorient the receiving antenna. Relocate the unit with respect to the receiver. Plug the unit into a different outlet so that the unit and receiver are on different branch circuits. Ensure that mounting screws and connector attachment screws are tightly secured. Ensure that good quality, shielded, and grounded cables are used for all data communications. If necessary, the user should consult the dealer or an experienced radio/television technician for additional suggestions. The following booklets prepared by the Federal Communications Commission (FCC) may also prove helpful:

How to Identify and Resolve Radio-TV Interference Problems (Stock No. 004-000-000345-4) Interface Handbook (Stock No. 004-000-004505-7) These booklets may be purchased from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.

10.2 Limited Warranty

Technologic Systems warrants this product to be free of defects in material and workmanship for a period of one year from date of purchase. During this warranty period Technologic Systems will repair or replace the defective unit in accordance with the following process:

A copy of the original invoice must be included when returning the defective unit to Technologic Systems, Inc. This limited warranty does not cover damages resulting from lightning or other power surges, misuse, abuse, abnormal conditions of operation, or attempts to alter or modify the function of the product.

This warranty is limited to the repair or replacement of the defective unit. In no event shall Technologic Systems be liable or responsible for any loss or damages, including but not limited to any lost profits, incidental or consequential damages, loss of business, or anticipatory profits arising from the use or inability to use this product.

Repairs made after the expiration of the warranty period are subject to a repair charge and the cost of return shipping. Please, contact Technologic Systems to arrange for any repair service and to obtain repair charge information.

WARNING: Writing ANY of the CPU's One-Time Programmable registers will immediately void ALL of our return policies and replacement warranties. This includes but is not limited to: the 45-day full money back evaluation period; any returns outside of the 45-day evaluation period; warranty returns within the 1 year warranty period that would require SBC replacement. Our 1 year limited warranty still applies, however it is at our discretion to decide if the SBC can be repaired, no warranty replacements will be provided if the OTP registers have been written.
  1. Through a 1.5 k ohm resistor