ADS1262: Reading incorrect or corrupted data

Hi Kinnari,

You say you are trying to debug your SPI function; could you elaborate on the problem, for example, what is the expected behavior of your SPI function and what are you observing?

If you have some additional information such as a schematic, code example, or logic analyzer capture that you could share it would be helpful!


Guessing by the fact that your issue appears to be related to the ADC's data rate, you might not be reading the ADC's data fast enough. I would suggest looking into using the /DRDY interrupt AND/OR using the "RDATA" command to try to capture faster and without data corruption. If you are not using the /DRDY signal as an interrupt then you must use to the RDATA command to avoid reading out data that is a combination of a partially old and a partially new conversion result (see section 9.4.7.2 in the datasheet).

Best regards,
Chris

Hi Kinnari,

Try to avoid reading data during a /DRDY falling edge.
During this time the output shift register is loaded with the new conversion result, so it is possible that while clocking out the old data that the shift register updates and you start clocking out values from the new conversion result.

OR

Try reading data with the "RDATA" command.
When you send the ADS1262 the "RDATA" command it loads the conversion result into a separate buffer and then clock out the data from this buffer. When reading data in this way, the old conversion result is not corrupted when a new conversion completes.

I hope that helps,
Chris

Hi Kinnari,

I think the problem lies within the for-loop you are using to read data. In it you send the RDATA1 command byte (0x12) to the device over and over. This will restart the read data operation and you'll probably see the STATUS or DATA1 byte repeated in the output.

Instead, try sending the 0x12 byte once and then clocking in 0x00 repetitively to read out the data, as shown in Figure 109 of the ADS1262 datasheet:

Best regards,
Chris

Hi Kinnari,

Keep the /CS signal held low for the entire command, as shown in the image above. If you toggle /CS in the for-loop it will terminate the current read data command and the output data won't make much sense.

Also, you might be interested in this blog post which shows an example of how to bit-shift and concatenate the data: e2e.ti.com/.../it-s-in-the-math-how-to-convert-adc-code-to-a-voltage-part-1
NOTE: In the case of the ADS1262 32-bit data, you don't need to perform the sign-extension.

Best regards,
Chris