Dealing with 8+8 = 16 bit triggers from two devices

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WAM
Posts: 1
Joined: Mon Jun 20, 2016 4:02 pm

Dealing with 8+8 = 16 bit triggers from two devices

Post by WAM » Mon Jun 20, 2016 4:18 pm

Hi everyone,

we are using a custom parallel-port cable that puts the 8-bit input from one device to the first 8 bits of the USB-receiver, and the 8-bit input from another device to the second 8 bits.
In ActiView, we can see two separate trigger channels, that show the correct values. However, when importing the data to EEGLab, the trigger values look wrong. I suspect that the two 8-bit channels are combined into a single 16bit channel, which is why the values add up. I saw that when recording data with FieldTrip, there's an option to automatically split the 16bit trigger channel into two 8-bit channels. Is there a similar option to record two separate channels in ActiView? If not, what is the best solution to split the 16bit event channel in EEGlab/Matlab?

Thanks for any advise,
best,
Wanja

Coen
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Re: Dealing with 8+8 = 16 bit triggers from two devices

Post by Coen » Fri Jul 01, 2016 3:41 pm

AND the 16-bit number with 255 to get the low byte and divide the 16-bit number by 255 to get the high byte.

Best regards, Coen (BioSemi)

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