TS-8820-dac

From Technologic Systems Manuals

The TS-8820 has 4 channels of 0 to +10 V DAC outputs. Each DAC channel has a positive and negative terminal connection. The negative side of the terminals are connected to the common ground of the TS-8820 and are non-isolated. The DAC terminals are on the P3 and P9 terminal blocks.

The DAC channels each have 12 bits of resolution that correspond to 0 to +10 V output. The upper bit (bit 15) of each register is a control bit that is used to synchronize the output of all 4 DAC channels. This means that all four registers can be updated without modifying the actual DAC output. Setting the control bit of any DAC channel register will case an update of the DAC output of all four channels. If the DAC register has not been modified, the update will still be sent but the actual output will remain the same. Reading this control bit will indicate if the synchronization is complete. Writing the DAC registers while the control bit is still asserted, indicating busy, will result in undefined behavior. The update process from setting the control bit to its completion takes approximately 3 microseconds.

When 0 is written to the control bit, the DAC values are updated internally in the FPGA but not transferred to the DAC. Thus any set of channels can be updated simultaneously by only writing a one on the final write.

The DAC channels can be controlled through 'ts8820ctl'. Note that the "--setdac" option to 'ts8820ctl' will always set the control bit of the selected register. See "ts8820ctl.c" and "ts8820.c" for an example of how this process works.

The following command would set DAC output 1 to 0.5 V:

ts8820ctl --setdac=1 --mvolts=500