Does the OpenBCI board/ADS1299 support differential input configuration. For instance, am I able to reference N1P against N2P? Or are the only reference pins SRB1/2?
Thanks biomurph. I only offered N1P against N2P as an example. It's good to know that differential input configuration only works within channel number (i.e. N1P against N1N). To further clarify, in order to use a differential input scheme, we must be sure to disconnect all N inputs from SRB1. Is this correct? Also, if not using the N pins at all, do you recommend connecting them all to SRB1? Would they otherwise be serving as a reference to the P channel without a body derived signal?
If you want to use a differential input scheme for each individual channel, then you should disconnect from SRB1 and SRB2, and depending on what you're doing, you might want to not include some channels in the BIAS drive...
I don't understand your question about not using the N inputs. You need to measure the P inputs against something...
the SRB pins essentially allow you to 'gang' the P or N pins together to easily attach to a single reference electrode.
Suppose an electrode is connected to N1P and N1P is connected to SRB2 which also has an electrode connected. What effect will the signal coming into N1N have on this circuit? Will the effect differ if N1N is connected or disconnected from SRB1 assuming no electrode is connected to N1N?
Seriously, the effect of attaching multiple electrodes through the N and P channel inputs in addition to the SRB inputs at the same time is crying out for empirical study. I honestly have no idea what would happen, but it is very unlikely that you will break anything in the process of testing it out.
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