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How to use ADS1299 in single-ended mode?

Di Jiao
Intellectual 815 points
Other Parts Discussed in Thread: ADS1299

Hi All,

I am a student from China and is trying to use ADS1299.

I am interested in the open-source project--OPEN-BCI and ADS1299 is used in it to sample electrical brain activity.

I tried to make the main board by myself for I can not buy one to test but the board I made can not work.

In the schematic diagram 1p, 2p,...,7p connected to nothing and I think the ADS1299 should be set in single-ended mode but  I have trouble to know how to set the ADS1299 like this. 

The Attachment contains the source code and the schematic diagram. I downloaded these several months ago from their website http://www.openbci.com/.

Sorry for my poor english.

Regards,

Di6661.ADS1299.zip

 

0218.ADS_V2-2-Sch.pdf

 

  • 0
    TI__Guru 66246 points

    Hello DI,

    Welcome to our forum!

    Single-ended mode implies that one of the inputs of a differential channel is tied to a known potential, while the opposite input is driven by the input signal source. This known potential is typically a DC voltage or a single reference electrode that is common to all input channels. Please refer to the Analog Input section of the datasheet for an explanation on the input ranges for single-ended and differential input configurations.

    The ADS1299 has a nice feature built in that allows you to drive the all the INxN inputs by connecting to a single pin called SRB1. The signal driven here will become the reference for all channels. Meanwhile, you would drive each INxP input with a separate electrode input. If you wish to use one of the INxP inputs to be your reference, the SRB2 bit can be set to select that signal and route it to the SRB2 pin. That signal should be buffered before it is driven to the INxN inputs through SRB1. Please refer to the datasheet and user's guide for illustrations and examples.

    Best Regards,