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ADS131A02: How to read ADC Values

Michael Liesenberg85
Mastermind 7560 points
Part Number: ADS131A02
Other Parts Discussed in Thread: ADS1298

Hi,

i have successfuly unlocked the ADS131A02 IC and have done some register initialization.

How do i read the ADC values?

I am using the ADC as asynchronous interrupt, have set the SPI word as 32Bit and Hamming code is not activated.

Once the DRY is fired, i send 0x00000000 to the TX SPI and i am reading  0x30220000 from the ADC back, regardless what the ADC input is:

How can i read both ADC channels? 

The only thing i found on the datasheet was this figure:

So do i have to send 0x00000000 for Status and then 0x00000000 to Channel 1 Data and 0x00000000 for Channel 2?

  • 0
    Prodigy 200 points
    Hi Michael,

    I have no experience with your device, but It looks similar to ADS1298.
    So general if you expect to recieve a message of 32b (stat,ch1,ch2 ect) via SPI you should also send 32b.

    Now you send 8b so you recieve 8b. Try to send 32b and check what you get.
    Hint1: check how SPI works
    Hint2: send the dummy data together, not seperate.
  • 0
    TI__Guru 63196 points
    Hi Michael,

    Thanks for your post.

    You are only sending 32 bits from what I can tell in your image. You need to send 32 bits for each word that you want to read. Currently, what you are reading is the Command Status Response 0x30 0x22 (0x00 0x00 are for 32-bit mode, LSB 0 padding format). I believe this means you reading the reserved register address 10h, which is equal to 0x22 (reserved for the future use). Can you double-check the SPI polarity and phase settings to make sure you are reading the correct values?

    In order to clock out the STATUS word + Channel 1 data + Channel 2 data, you will need to send 3 x 32 = 96 bits. The fourth word (CRC) is always enabled on DOUT. However, you do not have to read it if you wish. Simply disable /CS after reading Channel 2 and do not send the last 32 SCLKS.

    Best Regards,