Sending multiple triggers in one routine using serial port

Builder
2

Hi Somi,

Thanks for your question - we’re working on making some materials to help people with this - so your questions are really helpful thankyou! In answer to your third question, yes I do think a component for serial port communication would be helpful.

I think this should work. Add a code component and in the “Begin Experiment” tab use:

import serial
port = serial.Serial('COM1')

In your Begin Routine tab use:

pulse_started = False
pulse_ended = False

in the Each frame tab use:

    if mything.status == STARTED and not pulse_started:# where "mything" refers to a visual thing you are trying to sync the trigger to (so you could have one of these for different component's in the same routine
        win.callOnFlip(port.write([0x01])) # send the trigger but only when the window flips to ensure syncronisation
        pulse_started  = True
        pulse_ended = False
        pulse_start_time = globalClock.getTime()
    if pulse_started and not pulse_ended:
        if globalClock.getTime() - pulse_start_time >= 0.005:
            pulse_ended = True

Oh and in terms of setting the trigger value through a conditions file. If you have a column with the header “trigger_value” and write what you want the trigger value to be on each trial, you should in theory be able to use this in the port.write() command. So instead of port.write([0x01]) it would be port.write([trigger_value]) - please let me know if that works!

I think that should do the trick - but please do let me know if not!!

Hope this helps
Becca

PS. to check the frame timing is write here we also highly recommend checking with a photodiode for visual stimuli if you can.

1 Like