TS-4200 Software Development

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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.

1 Cross Compiling

While you can develop entirely on the board itself, if you prefer to develop from another x86 compatible Linux system we have a cross compiler available. For this board you will want to use this toolchain. To compile your application, you only need to use the version of GCC in the cross toolchain instead of the version supplied with your distribution. The resulting binary will be for ARM.

[user@localhost]$ /opt/arm-2008q3/bin/arm-none-linux-gnueabi-gcc hello.c -o hello
[user@localhost]$ file hello
hello: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.14, not stripped

This is one of the simplest examples. If you want to work with a project, you will typically create a makefile. You can read more about makefiles here. Another common requirement is linking to third party libraries provided by Debian on the board. There is no exact set of steps you can take for every project, but the process will be very much the same. Find the headers, and the libraries. Sometimes you have to also copy over their binaries. In this example, I will link to sqlite from Debian (which will also work in the Ubuntu image).

Install the sqlite library and header on the board:

apt-get update && apt-get install -y libsqlite3-0 libsqlite-dev

This will fetch the binaries from the internet and install them. You can list the installed files with dpkg:

dpkg -L libsqlite3-0 libsqlite3-dev

The interesting files from this output will be the .so files, and the .h files. In this case you will need to copy these files to your project directory.

I have a sample example with libsqlite3 below. This is not intended to provide any functionality, but just call functions provided by sqlite.

#include <stdio.h>
#include <stdlib.h>
#include "sqlite3.h"

int main(int argc, char **argv)
{
	sqlite3 *db;
	char *zErrMsg = 0;
	int rc;
	printf("opening test.db\n");
	rc = sqlite3_open("test.db", &db);
	if(rc){
		fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
		sqlite3_close(db);
		exit(1);
	}
	if(rc!=SQLITE_OK){
		fprintf(stderr, "SQL error: %s\n", zErrMsg);
	}
	printf("closing test.db\n");
	sqlite3_close(db);
	return 0;
}

To build this with the external libraries I have the makefile below. This will have to be adjusted for your toolchain path. In this example I placed the headers in external/include and the library in external/lib.

CC=/opt/arm-2008q3/bin/arm-none-linux-gnueabi-gcc
CFLAGS=-c -Wall

all: sqlitetest

sqlitetest: sqlitetest.o
        $(CC) sqlitetest.o external/lib/libsqlite3.so.0 -o sqlitetest
sqlitetest.o: sqlitetest.c
        $(CC) $(CFLAGS) sqlitetest.c -Iexternal/include/

clean:  
        rm -rf *o sqlitetest.o sqlitetest

You can then copy this directly to the board and execute it. There are many ways to transfer the compiled binaries to the board. Using a network filesystem such as sshfs or NFS will be the simplest to use if you are frequently updating data, but will require more setup. See your linux distribution's manual for more details. The simplest network method is using ssh/sftp. You can use winscp if from windows, or scp from linux. Make sure you set a password from debian for root or set up a shared key. Otherwise the ssh server will deny connections. From winscp, enter the ip address of the SBC, the root username, and the password you have set or the use of a shared key. This will provide you with an explorer window you can drag files into.

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

For scp in linux, run:

#replace with your app name and your SBC IP address
scp sqlitetest root@192.168.0.50:/root/

After transferring the file to the board, execute it:

ts:~# ./sqlitetest 
opening test.db
closing test.db

1.1 Kernel Compile Guide

WARNING: Backup any important data on the board before continuing.

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

RHEL/Fedora/CentOS:

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

Ubuntu/Debian:

apt-get install build-essential libncurses5-dev libncursesw5-dev

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

Set up the Sources and Toolchain

# Download the cross compile toolchain (EABI)from Technologic Systems:
ftp://ftp.embeddedarm.com/ts-socket-macrocontrollers/ts-4200-linux/cross-toolchains/arm-2008q3-72-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2

# Extract to current working directory:
tar xvf arm-2008q3-72-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2

# Download the Kernel sources
wget ftp://ftp.embeddedarm.com/ts-socket-macrocontrollers/ts-4200-linux/sources/linux-2.6.36-ts-src-latest.tar.gz

# Extract the Kernel Sources
gzip -dc linux-2.6.36-ts-src-latest.tar.gz | tar xf -

cd linux-2.6.36-release/

Configure the Sources

The kernel sources need a few variables to be exported.

# Set the CROSS_COMPILE variable to the absolute path to the toolchain.  This may be different for your system:
export CROSS_COMPILE=/opt/4200/arm-2008q3/bin/arm-none-linux-gnueabi-

# Normally, ARCH will be set based on your build hosts architecture.
export ARCH=arm

This sets up the default configuration that we ship with for the TS-4200

make ts4200_defconfig

This will bring up a graphical menu where you can edit the configuration to include support for new devices. For Example, to include support for a Prolific USB to serial adapter you would go to 'Device Drivers -> USB Support-> USB Serial Support' and then select 'USB Prolific 2303 Single Port Serial Driver'. Since the kernel only has a limited space try to build build drivers as modules whenever possible.

make menuconfig

Build the kernel Once you have it configured, start building. This usually takes a few minutes.

make && make modules

The new kernel will be at "arch/arm/boot" in a compressed format called zImage. The uncompressed version is simply called Image. With the default partitioning scheme it is REQUIRED that the kernel be < 2620416 bytes in size. If you need to shorten the size, try including your changes to the kernel as modules instead. Otherwise you will need to resize the kernel partition to account for the size difference.

Install the kernel Now that you have a kernel you can install it as you would our stock. See the #Backup / Restore section for examples on writing this to disk.

Install Modules Script to make directory and install modules

./build-module-bundles.sh

The build-module-bundles.sh script is meant to be run as a user (not root) and will create directories and install modules to them. The directory structure is created at /home/`whoami`/src/ts-4200/dist/<ts4200 kernel release number>/modules-install/. In that directory is initrd-modules/, lib/, and modules-<ts4200 kernel release number>.tgz.

initrd-modules/modules.tar.gz is a tarball that contains a minimal number of modules. This tarball needs to be copied to the initrd partition of the boot media. The boot process of the board will automatically un'tar this and insert any necessary modules.

Now the contents of lib/ can be copied to the root of the TS-4200. It is also possible to copy over modules-<ts4200 kernel release number>.tgz to the TS-4200 and unpack it in the root linux directory. You may want to remove any old modules on the board in /lib/modules/* before copying them to the board to rule out any incompatibilities. Once you boot up to the board, you need to run 'depmod' once to calculate module dependencies. You can then run 'modprobe' with the device drivers you've added. For the Prolific adapter added in the example, this would be:

modprobe pl2303