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ADS131A02: Problem with configuring the ADC

Ewout Boks
Prodigy 190 points
Part Number: ADS131A02

Hi,

I try to write a driver for communication with the ADS131A02. I do not succeed in getting any of the response listed in the datasheet.

Firs, I set try to unlock the device:

after that, I try to read the status (NULL cmd) and start a conversion :

and

my device is HW configured as 32 bit word, no Hamming , asynchronous interrupt mode.

I keep getting a value 0x02 back, no ack or anything else. What am I doing wrong?

Thanks,

Ewout Boks

  • 0
    TI__Mastermind 38745 points

    Hey Ewout,

    A few things:

    • It looks like you always get 0xFF02 back which seems to indicate the device is still in the "READY" state. Do you ever receive the proper acknowledgement to the UNLOCK command?
    • You will also need to send the WAKEUP command since the device powers up in standby mode
    • To receive 2 channels worth of data plus the status word in 32-bit output mode, you will need to extend the frame to send a total of 32*3 = 96 SCLK periods to shift out all the data.

    Take a look at the flow chart in figure 109 in the datasheet. It gives you a pretty good idea of what will be required to get the device up and running.

    Regards,

    Brian Pisani

  • 0 in reply to Brian Pisani
    Prodigy 190 points

    Hello Brian,

    thanks for pointing out the flow diagram - I had overlooked it.

    Once I implemented the suggested flow the device behaved as expected.

    One thing I would like to point out it the missing clarity about msbyte and lsbyte in commands and data response in the datasheet - it took me a while to figure out what the ads131a02 expects and in what order I get data back.  Apart from that, the IC performs really well !

    Thanks,

    Ewout Boks

  • 0 in reply to Ewout Boks
    TI__Mastermind 38745 points
    Ewout,

    Thanks for the feedback!

    Brian