The aux channels can also be used to receive external trigger information, when desired to sync an external stimulus event with the corresponding EEG.

Sample rates are not guaranteed to be EXACTLY 250.000 Hz. There is something called 'drift' on all EEG amplifiers. For example on the Cyton, your actual sample rate may be 249.7. The only way to synch

I previously mentioned how most experiments do their P300 experiments. It requires using what is called an external trigger that is simultaneously recorded with the EEG signal. You can record this tri

In EEG trials, a recording or segment usually encompasses both before and after the stimulus. Thus you need to know the exact time point when the stimulus is applied within the segment. This is genera

Yet another way you could do the triggers: have the PIC24EP (in addition to outputting the tones), output a specific 1 or 2 level "DC" level signal when the tone is on. (And turn off when th

These will give precise trigger locations in your EEG record to look for the P300.

For recording trigger signals, yes you can use either actual EEG channels, or the Aux channels, of which there are 3.

Many P300 experiments are done using an external trigger signal that is recorded alongside the EEG channels. With Cyton, you can setup the external trigger to be recorded on the Aux channels.

There might also be a way you could use a 'trigger' digital or analog signal from the Arduino to the Cyton. This trigger could fire on a specific condition in your Arduino data stream, for example the

just base your ERP and DSP calculations on the trigger information. 

Both my comment and the link above, emphasize the importance of using trigger information for your ERP protocols. Recording the trigger information directly on a Cyton EEG channel or Aux channel is op

My suggestion as far as ERP studies go, is that you base your analysis on the optical trigger alignment. And forget about precisely counting 250.00 samples per second. If you do need some sort of drif

You said previously you were using the optoisolator example circuit in the trigger tutorial example.

This works and has decent response. However I recently found out that photoresistors can have a slower response time / rise time than you might expect. In the milliseconds range, possibly around 5 or

re: TCP sync. No, instead use the Aux channel to record your event trigger.

If you are providing stimulations that evoke potentials, have you considered using the Cyton Aux channel(s) to record your external trigger events?

This thread shows how to do external trigger from a photoresistor, on Cyton. I sent you an email with details on how you might adapt this approach to Ganglion.

I have already cc-ed you on an email with more details on how to achieve external trigger with Ganglion, using an Aux channel from one of the Simblee digital or analog pins. This trigger signal would

The only practical way to sync your two amps is with a periodic external trigger mechanism. Ganglion has Aux input pins on the board that can be used for this.

in LabVIEW to do that reads in the Cyton and triggers a DIY current controlled, electrically isolated tACS  device, but the code can be stripped down to monitor various band power estimates and trigg