ADS1299 interface with Arduino UNO

Momin_2089

Hi, I have made an EEG module and trying to get data from it using Arduino IDE(I have attached sample code and my PCB schematics). I am using ads1299 with bipolar supply. So far I have just Configured CONFIG3 register and CHnSEL registers as following

ADS.WREG(CONFIG3,0xE0) ;//Enabling internal reference
ADS.WREG(CHnSET,0x68); //Selecting normal mode and closing SRB2

I’m able to get data from all 8 N-channels with respect to SRB2(as a reference electrode).
Problem is I want to include BIAS electrode. As far as I know about BIAS electrode, it is used for noise cancellation in a closed loop form ( As discussed in openBCI site : https://docs.openbci.com/docs/01GettingStarted/02-Biosensing-Setups/EEGSetup ).I want to use my setup same as in the link of openBCI but with all 8 channels.
As there are many BIAS registers in ads1299 so I’m confused about there configuration .It will be great if someone could help me in configuring registers so that if I connect SRB2 to one ear lobe and BIAS to other and all other electrodes on EEG head cap I would get data with much lesser noise.

Billh

The bias electrode gets it name from its historical use, with older analog equipment that was powered from AC current, as a source of a tiny bit of cancelling AC voltage to offset mains noise. Filters were not as good back then. A battery powered EEG machine, or modern well isolated electronics in general, does not need a "bias" source, in that sense. So just add it as a ground. With 8 electrodes around the head, I would put the ground electrode in the center, either at the peak of the center scalp or somewhat to the front of that, more or less equidistant from your 8 other wires. Or, if you are using a reference electrode on one ear, you can use the other ear for the ground, just as the tutorial does, even with all the other leads in use.