TTL trigger output synchronization for external electrical stimulator

Frisardi56 · May 27

Hello,

I am evaluating Cyton + Daisy for advanced neurophysiological EMG reflex studies.

My setup would involve:

piezoelectric reflex hammer (trigger input)
external electrical stimulator
jaw jerk reflex recordings
silent period analysis
paired stimulation paradigms
recovery cycle studies

I already found documentation about external trigger INPUT through GPIO pins.

My main question is about TRIGGER OUTPUT.

Can Cyton generate a deterministic hardware TTL trigger OUTPUT capable of synchronizing an external electrical stimulator with millisecond precision?

More specifically:

Can Cyton send hardware trigger pulses (TTL) to external devices?
Is trigger output timing deterministic and stable enough for reflex latency studies?
What is the expected trigger output jitter/latency?
Can trigger input and trigger output operate simultaneously during acquisition?
Has anyone used Cyton for:

trigeminal reflex studies
jaw jerk recordings
silent period paradigms
paired pulse stimulation
recovery cycle studies

Thank you very much.

wjcroft · May 27

Hi Frisardi,

In addition to the 8 or 16 EEG channels, Cyton can record external device opto-isolated trigger channels, as 'aux input' channels. But Cyton has no OUTPUT trigger generation capability. This page shows what auxiliary channels (pins) are supported, when 'board mode' is switched to either analog or digital mode.

https://docs.openbci.com/Cyton/CytonSDK/#board-mode

2 = Analog mode - Reads from analog pins A5(D11), A6(D12), and A7(D13) as well.

3 = Digital mode - Reads from analog pins D11, D12, D13, D17, and D18.

Our suggestion is that you use another microcontroller or other timing source to generate your output timing pulses. Then capture with the Cyton aux channels, both that output pulse, and your reflex physiology trigger inputs.

Regards, William

TTL trigger output synchronization for external electrical stimulator

Comments