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ADS1246 and ADS1248

Dian Mladenov
Prodigy 130 points
Other Parts Discussed in Thread: ADS1246, ADS1248

Hi all,

I have a designed board with ADS1248 (to read RTD) and ADS1246 (to read analog values). I do not have any problems with ADS1248 (so far, I can read back control registers), but I can not change the data rate of ADS1246. It is always 5SPS. I can not read back register SYS0 (address 03h). I am reading continuously ADS1246 and reading is OK. I checked with oscilloscope (with memory) SCLK, DIN and CS and are OK according to the manual.

Any idea where is my mistake?

Thanks in advance!

  • 0
    TI__Guru* 94285 points
    Dian,


    There shouldn't be any reason that the ADS1248 is different than the ADS1246. The digital section should be exactly the same.

    For the ADS1246 SYS0 register, what do you get when your read it now? My recommendation would be to first try to read back the register and get an oscilloscope shot to make sure there aren't any problems with the SPI communications. Once you do that, try writing to the same register to set a different data rate and get a scope shot of that too. Post the results back so I can take a look at the communication.

    Usually, I also have people check the SCLK rate, the phase, and the polarity. Then check /CS hold and setup times as the device is being written to and read from. However, since you have the ADS1248 working, this is less likely.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Prodigy 130 points
    Thank you Joseph for your quick answer. ADS1246 I am getting back 0x00. Now I will do rest of your recommendations.
    Thank you again,
    Dian
  • 0 in reply to Dian Mladenov
    TI__Guru* 94285 points
    Dian,


    Since 00h is the default result, it's not too revealing. Let me know when you are able to get a scope shot or logic analyzer read of the register, when you try to change the value.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Prodigy 130 points
    I found the problem. I had chip select high, between command a reading back register.
    Thank you again Joseph!
    Dian