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CCS/ADS114S08EVM: Unable to read ADC data

Part Number: ADS114S08EVM
Other Parts Discussed in Thread: ADS114S08

Tool/software: Code Composer Studio

Hello Team,

We are able to read and write the ADC registers. But we are unable to read the ADC data. We are able to read some default value at the beginning but then no values are read.

Attached is the sequence of commands we are sending.

flowchart_ADC RegisterV2.pdf

 

Thanks

Abhijit

  • Note there was a related post that we closed :  https://e2e.ti.com/support/data-converters/f/73/p/948514/3504938#3504938

    We will work the questions on this thread.

  • Hi Abhijit,

    Welcome to the E2E forum!  As you have labeled this post as working with the ADS114S08EVM, I assume that you are attempting to communicate to the ADS114S08 using the connection points on J3.  As you have stated that you can read and write registers, I also will assume that the onboard TIVA is being held in a reset state by adding the jumper to JP1, and are still powering from USB.

    As to the settings shown in the flowchart, there are some discrepancies with respect to the descriptions. First it is not clear which reference you are intending to use, but by the settings you are disabling the reference buffers and using the REF0 input pair.  However it would appear that you would intend on using the IDAC source, which requires that the internal reference be turned on to be able to source current.  For ratiometric measurements the REF1 input should be used as the reference source for the conversion.  This also assumes that there is something connected (even if it is a short) between AIN1 and AIN0 to complete the current path.  

    You also show that the data rate should be 100sps, but the value described to be written to the register is actually selecting 20sps data output rate.

    For the IDAC current to actually flow, two register settings are required.  One is to set the output current value, and the second is to select the pin where the current is to be sourced.

    Can you send me the configuration you are reading back from the ADS114S08?  Can you also send me information as to how you are connecting the inputs for AIN1/AIN0?  As far as the communication, can you send me oscilloscope or logic analyzer plots of the RDATA command?

    Best regards,

    Bob B