Tool/software:
Hi team,
There is a problem of using ADS1255 adc in continue mode reading.
The fclk for ADS1255 is 8MHz and operating in 30Ksps continue mode.
The SPI read out program refering DRDY signal falling edge to read out the 3 bytes data.
However, the readout will randomly wrong in our testing.
The master SPI is tiva SSI driver code and we also measured the SPI waveform and it looks like ok.
Below diagram is the wrong reading we captured.
The typical error read out looks like the MSB byte duplicated of the reading and casued the 24 bits (3 bytes ) data wrong.
ex: AA BB XX are the neighboring values.
The abnoraml one might like AA AA BB.
Another wrong case is the Middle byte duplicated like AA BB BB.
We have some tried but the error still randomly happen.
1. reduce to 15K sps
2. adjust SPI clock rate (2MHz ~ 1.6MHz)
We think the SPI read timing is no differnet in correct / wrong case and should meet ADS1255 spec.
We think the fclk 8MHz and the operating setting 30Ksps should still meet the specification.
What might be the problem and any suggetion of this?
Regards,
Paul