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TMS320F280041C: ADC Simultaneous Sampling

James McKenna
Prodigy 126 points
Part Number: TMS320F280041C
Other Parts Discussed in Thread: BOOSTXL-DRV8323RS

I'm having some confusion designing the ADC sampling routine for the 64pin F280041C. We do not need to use any PGAs and the ADC voltages all come in at 0V-3.3V. Looking at the example of the C2000_MotorControl_SDK solutions with the BOOSTXL-DRV8323RS, the F280049C samples motor current, motor voltage, battery voltage, and throttle.

Motor current sample uses ADC channels A14, B7, and C7 and ADC_SOC_NUMBER0.
Motor voltage sample uses ADC channels A5, B0, and C2 and ADC_SOC_NUMBER1.
Battery voltage sample uses ADC channel B1 and ADC_SOC_NUMBER2.
Throttle voltage sample uses ADC channel B3 and ADC_SOC_NUMBER3.

If I'm correctly following this logic then the best design is one where ADC_SOC_NUMBER only samples one input from each ADC channel? For example the following would not work because we are sampling twice from channel B on the same SOC.

Motor current sample uses ADC channels A4, B4, and B1 and ADC_SOC_NUMBER0.

Does this make sense?

  • +1
    TI__Mastermind 29905 points

    Hi James,

    SOCs are exclusive to each ADC module.  This means that ADCA has its own ADC_SOC_NUMBER0 to SOC15 (16 per ADC module).  ADCB and ADCC have their own SOCs as well.  The SOC operation gives users flexibility to configure the ADC in that users can independently assign ADC channels to all the 16 SOCs as well as trigger sources and priority/round robin options for the SOC conversion sequencing.  It is also a valid use-case to assign the same ADC channel for all 16 SOCs, for instance if 16x oversampling is desired.  Each SOC also has its own corresponding result register (ADCRESULT0 - ADCRESULT15) which is also exclusive per ADC module.

    In regard to the SDK example, it just means that all the three ADC modules are effectively doing simultaneous sampling on three different signal sources for a common trigger.  This is only possible because of the features of the SOCs.

    Hope this clarifies your concern.  Let me know if you have any other questions regarding the SOC operation.

    Regards,

    Joseph