Hi, I can easily install a switch for AC trigger but I am not clear on it's purpose.
The pulse length can be hard coded as long as I can change it in the code easily, I assume I would be able to. Once set it would likely never be changed. The pot to change barWidth is all that is needed here and I have that along with the readout on display.
It would be nice to have the polarity of the output switchable and I think I can do that by swapping pins 2 & 4 on the DAC. So just + first should be OK.
To answer the last question I need to understand what you refer to as AC trigger.
Thanks, Tom