I am trying to get the offset by shorting the inputs using the CHx_CFG registers (Page 64: https://www.ti.com/lit/ds/symlink/ads131m08.pdf) but it's not behaving as I expect it.
Below is table of the mean value over 4K samples at 4K sampling rate at different GAIN settings.
When it is not physically shorted, the offset keeps changing with the gain values, but once I physically short it, the value remains consistent across gain settings.
I am perhaps misunderstanding this feature and there is an explanation for this. But I am in the dark right now. So if someone can please throw some light on this, I'd be grateful.
Gain | Internal short using CHx_CFG Register | External Short | External + Internal Short |
0 | 261 | 581 | 664 |
1 | 587 | 589 | 672 |
2 | 1119 | 584 | 677 |
3 | 4408 | 573 | 672 |
4 | 6394 | 567 | 671 |
5 | 35111 | 557 | 664 |
6 | 70748 | 558 | 652 |
7 | 141995 | 556 | 657 |
It's running off 8MHz clock, all channels enabled, in continuous conversion mode. I've only changed GAIN and CHx_CFG Registers.