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Original question:

ADS1298: Breakout and Arduino Due

ADS1298: Finding useful EMG data after connecting to ADS1298

Spencer Iverson
Prodigy 110 points
Part Number: ADS1298

I have successful communication with the ADS1298 board (at least I believe I do).  When I try and read values from any of the channels via electrodes, I get the following on my serial monitor:

...

-56649 -37957 -3074 4610
-15104 3526 -3084 4583
26966 45696 -3079 4598
26941 45712 -3085 4589

...

26941 45702 -3068 4579
25253 44013 -3091 4582
-54862 -36122 -3082 4572
-56658 -37940 -3070 4604

...

(I'm only printing the first four channels after the 3 bytes of header information)

The values I get are fairly consistent and change from low to high consistently as well.

I'm again following Adam Feuer's GitHub for the ADS1298 breakout board. 

Am I missing a reference voltage to stabilize my values?  Or some sort of external filters for the electrodes?

I attempted to follow the instructions for RLD here https://e2e.ti.com/support/data-converters/f/73/p/414236/1472373.

I'm just a bit lost in attempts at getting EMG data. 

Thanks for any help,

Spencer

  • 0
    TI__Guru 55342 points
    Hi Spencer,

    Thanks for your post and welcome to the forum!

    Unfortunately, we're not experts on the EMG application, so the help we can offer is limited.

    You will need a method to bias the measurements, or "stabilize" as you mentioned. Using the RLD electrode will ensure that the signals are centered on a common-mode range that is within the limits of the PGA, and will keep your measurements from clipping. If you don't want to use the RLD electrode, you can also tie the inputs to mid supply as shown by R19, R20, and C27 in this document: www.ti.com/.../sbau171d.pdf

    Either of these methods will help reduce the noise in your measurements. Check out the BIOFAQ in my signature to see the RLD app note and how to do code to voltage conversion, those posts may help.