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ADS1255: Wrong frame at 0x00

Romain FRENEHARD
Prodigy 40 points
Part Number: ADS1255

Tool/software:

Hello,

I used the ADS1255 to measure a NTC. The component works and I receive on SPI bus the good value exept during the value 0x00. To proove the issue, I use potentiometer. If a set the position and I don't touch it, I receive the 0x 00 00 17, that it's good and sometime, I received wrong frame with a value of : 0x 00 7F 0x90. In attachement I put both graph.

For me, the soft is good because we can see that the frame change on the SPI.

Do you have an idea why the value converted by the ADC change without change the potentiometer position. The changing is important to be a problem with micro mouvement of the potentiometer . 

Thank you

Best Regards

  • 0
    TI__Guru 52146 points

    Hi Romain FRENEHARD,

    Can you label your logic analyzer captures? I am not sure which signals are which, though I could probably guess. Also, can you send overall captures (like the ones you sent) and zoomed in captures? I cannot really read anything from the captures you sent, but it is good to be able to see the entire frame

    Also, what do you mean by "wrong frame value"? Are you saying that you set the potentiometer to a certain value, and the ADC measures it correctly, then after some time the ADC measurement is off?

    Is the data value from the ADC constant, then a single conversion data is off, then it goes back to the value you expect?

    Please provide more data / tables / plots to explain how this error manifests itself as well as what troubleshooting steps you have taken to fix it (and their outcomes). I can only help you with the information you give me, so please be detailed

    -Bryan