the signal from pin D17 in digital mode, the trigger signal will interfere with the EEG signal.

re: time stamp accuracy / external trigger

I have seen the "External Trigger on OpenBCI Cyton Board", but i didn't get this. Does it require a separate external device and is connected to external triggers? And I didn't have external

The analog sensor data stream is recorded SIMULTANEOUSLY with the data samples. EXACT synchronization. NO 'time-stamps' involved. No 'markers' needed. You just measure the two white vs black analog va

https://openbci.com/forum/index.php?p=/discussion/3055/external-trigger-question-on-photodiode-resolved

Did you see the External Trigger page:

I wanted to explore the option of external triggers for visual stimuli, we show images to participants and want to have a trigger exactly when image is displayed on the monitor.

example, we could still use D11/D12 or D13 as trigger input following the tutorial you showed, right?

example, we could still use D11/D12 or D13 as trigger input following the tutorial you showed, right?

You want to setup an opto isolated connection from the trigger source (Pi?) to Cyton. This trigger info is recorded simultaneously with the samples, in three 'Aux' values, 16 bits each.

However the digital port D11, D12, D13, D17, D18 could be used by a Raspberry Pi to externally trigger the Cyton from what I got from the documentation. Do you confirm? Can those ports also be used fo

"External Trigger" is what you want.

The best approach and most accurate with Cyton, is to use the 'external trigger' inputs.

Arduino. When I input that signal as an external trigger for the Cyton, it always chatted. At least it is responding, but how can I solve this problem?

Can you explain the goal of your project, what are you trying to measure / demonstrate? What are you attempting to synchronize with the external trigger(s) or 'markers'? The external trigger approach

The third question is about the external trigger. How many external triggers I could use at the same time? As there are 5 pins, I think I could use 5 external triggers if I use the usb dongle. But acc

I need to collect raw signals along with stimulus onsets (annotation) for epoching. Is there a way to do signal acquisition with event markers (not by external button trigger) in OpenBCI GUI? if not,

Cyton (not Ganglion), has an External Trigger capability, using 3 additional 'Aux' channels.

In general, the External Trigger method you mention, has the tightest coupling with the EEG data stream because it is sampled and recorded at the same moments (sample rate) as the EEG samples. Any 'ma

You can use another optoisolator. Be sure the specifications match the one used in the External Trigger link. Also possible that the pin numbers differ.