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ADS1248: ADS1248 - Code help

Mark Witt
Prodigy 100 points
Part Number: ADS1248
Other Parts Discussed in Thread: ADS1234

Hello,

We recently redesigned our product which included switching from the ADS1234 to the ADS1248.  The new software setup for the 1248 is enough to cause our software engineer problems and he's stuck.  He is able to communicate to the part and read the registers but the results are all 0x7FFFFF.  Can you provide any sample code or setup information to solve this issue? 

Thanks,

Mark

  • 0
    TI__Guru* 99115 points

    Mark,


    There might be some code that I can dig up, but it's better just to debug what you have.

    Since you're reading 7FFFFFh, I'd guess that you're close to get data out. 7FFFFFh is the equivalent of a positive full scale reading, which may imply that you have a reading that is over ranged.

    First check that you have the proper reference input selected. If you don't have the proper reference selected, it might give you an over range result. Imagine that your reference is set to 0, and you have any positive input - you'll always be over ranged.

    Second, check the PGA gain setting on the device. If the PGA is set to 128, and you're putting in a voltage that's in the hundreds of mV, you'll over range the input regardless of whatever reference input you use.

    If none of those suggestions pan out, I'd try some simple debugging by selecting the internal reference, setting the PGA gain to 1 and then measuring something known, like the internal temperature sensor. It will give you a known reliable voltage that you can read out as a test. At the very minimum, short the inputs to mid-supply so you're guaranteed not to be over ranging the PGA.

    If there continue to be issues, post back and we can talk about the code.


    Joseph Wu