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Author Topic: Electrodes l Leads - Inputs  (Read 1660 times)

Samuele Greggio

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Electrodes l Leads - Inputs
« on: January 17, 2016, 02:50:04 PM »
Hello,
I'm developing an appliction to read EKG signal.
What is the corrispondence between electrodes (white, red,  black) , leads (DI, DII, DIII), and analog input to  read?
Thank you,
Samuele

LubOlimex

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Re: Electrodes l Leads - Inputs
« Reply #1 on: January 26, 2016, 12:07:54 PM »
Hey,

EEG-SMT samples the analog signals and builds a 17-byte packet which is transmitted at 256Hz, using 1 start bit, 8 data bits, 1 stop bit, no parity, 57600 bits per second. Minimial transmission speed is 256Hz * sizeof(modeeg_packet) * 10 = 43520 bps.

EEG-SMT is based on the OpenEEG project. We used their data format which is defined in the so-called "firmware 2" of OpenEEG. The format is showed at this link (the modeeg_packet structure might be found in the beginning):

http://openeeg.sourceforge.net/doc/modeeg/firmware/modeeg-p2.c

I recommend you to also inspect the firmware sources we have shared here: https://www.olimex.com/Products/EEG/OpenEEG/EEG-SMT/resources/EEG-SMT_firmware.zip

Check the screenshot below which I took yesterday - it shows a proper raw stream of data coming from EEG-SMT.

I used this terminal program: http://www.der-hammer.info/terminal/

The required settings are visible in screenshot (most importantly the baud rate should be 57 600 and the data should be set to hex).



Best regards,
Lub/OLIMEX
Technical support and documentation manager at Olimex