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TMS320F28377D: use the CMPSS comparator to realize the protection of ADC differential sampling

Part Number: TMS320F28377D
Other Parts Discussed in Thread: C2000WARE

Dear team,

The customer wants to use the CMPSS comparator to realize the protection of ADC differential sampling. Please help to check  how to realize it?

  • Susan,

    Can you elaborate on what "protection of ADC differential sampling" means to the customer and perhaps how they would typically do this with discrete components?  I do not understand the context.

    -Tommy

  • Dear tlee:

    Thanks for your Reply!

    I use ADCINA2 and ADCINA3 as differential ADC to sample the Volt, When this Volt over a value to shut down PWM,
    How can use CMPSS to realize it? I don't know how to configure CMPSS!

  • user3455617,

    There are CMPSS examples in C2000Ware that might be helpful:

    ~\C2000Ware_XXXX\driverlib\f2837xd\examples\cpu1\cmpss
    ~\C2000Ware_XXXX\device_support\f2837xd\examples\cpu1

    However, the CMPSS is not able to natively interpret the signal characteristics that are required by the ADC in differential mode.  CMPSS is designed to monitor for voltage crossing between the comparator inputs, whereas the ADC requires its differential signals to cross at the midpoint of the fullscale range.  So if the ADC input signals are conditioned properly, the CMPSS would always trip at the midpoint.

    For continuous CMPSS monitoring, the signal would need to be converted to a single-ended input.  If periodic monitoring is acceptable, the ADC Post Processing Block (PPB) can also generate an event signal to trip the EPWM if the conversion results exceed predefined threshold limits.

    -Tommy