Converting analog stimulus timing signal measured with a photoresistor to digital signal

Hi,
I am measuring visual stimuli using two photoresistors. I followed the expamples provided in https://openbci.com/community/measuring-stimulus-timing-with-a-photoresistor/, however these signals are showing as analog signals on my OpenBCI GUI. Please is there a way to first convert the analog signals to digital signal so that I can use the digital 'read mode' on my GUI widget?

Kenny

Comments

  • wjcroftwjcroft Mount Shasta, CA
    edited January 7

    Kenny, hi.

    If you are seeing the trigger level show up and looks valid with the GUI widget and 'analog read mode', then why not employ your own threshold detection test, for example, x.x volts = ON, y.y volts = OFF. Etc.

    Otherwise you depend on the thresholds set in the GPIO logic pins for digital level zero / one detection. Which may not be well defined.

    William

  • Hello wjcroft,

    Thank you for your response. I am not really sure how to go about that. Could you please expatiate more on how I should do this?

    Kenny

  • wjcroftwjcroft Mount Shasta, CA

    Kenny,

    What is the range of your analog mode input signals? For example, if OFF = 1V and ON=2V, then you could do a simple test to determine if the signal is ON or OFF. Such as, signal < 1.1V is off. Signal > 1.9V is on. Etc. Or add some de-noising if necessary.

    William

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