ElectronicDesign/TriggerSignalGenerator (2005-12-20 00:45:12)

Earlier, the in-firmware (mst.. msp.. commands) OutputTrigger was used to drive trigger signals.

To test MembersPage/FiatStilo trigger code, we wrote new code (SVN firmware testing) to use PC soundcard as trigger signal generator.

The code supports

Primary trigger

Secondary_trigger

TODO: make secondary trigger (edge positions) parametrizable from commandline

Particuarly useful for GenBoard/Manual/InputTriggerCamSync. See [shop round testlight] item that is also very useful.

Testing on the table can save hours or days of - sometimes frustrating - work. Small config or other errors can be very frustrating and difficult to find. If one knows that his config and ECM inputs and firmware are fine, she eliminated 70% of the problem-sources, and cut the number of possible problem-combinations to 1/10th.

The cost is unfairly small, a few simple and cheap HW, and some work in the warm room.

TODO:


Hardware - direct connection

I simply connected the soundcard output to the ECM inputs, without any capacitor or resistor (the ECM has protection for the inputs anyway).

I listened via a headphone to both channels to tell crank from cam, before inserting the econoseal receptacles.

With VR, there is no doubt it should work.

With HALL input, maybe I was just lucky. The output level for the soundcard is 2V peak to peak, which is lower than the 0V/5V input that HALL is designed for. While it worked for me fine for first try, maybe I was lucky, and one needs to use 1..2 resistors to divide signal towards GND (1 resistor in the 10k range from input to GND should be enough to bias the input, the soundcard output is likely capacitively decoupled anyway). If in doubt, run mdf01mdkff menu-command, and in output watch for B.=.... benchstats. That should reveal if primary/secondary trigger pulses are detected with the right frequency.


See also