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TMS320F28P650DH: ADC channel strange behaviour.

Hang Yang
Expert 3081 points
Part Number: TMS320F28P650DH


Tool/software:

Hi experts,

My customer is observing strange behavior in the ADC.

case 1:

config:

Ch 7 sampling A4

result:

Ch7 = 0 (abnormal)

case2:

config:

Ch7 sampling A4 

Ch10 sampling A4

result:

Ch7 = 0

Ch10 = expected value.

case 3:

config:

Ch6 sampling A4

Ch7 sampling A4

result:

Ch6 = expected value

Ch7 = expected value.

any idea what's causing the abnormal on A4 sampling?

  • 0
    TI__Prodigy 230 points

    Hi Team,

     Could you please provide more information on below:

    1. What do Ch<x> mean?  Are you referring Ch as ADC SoC -> Ch7 means SoC7?  As I understand A4 is the external pin input which the customer is trying to sample.
    2. What is the trigger mode selected for these configurations? 
    3. Can you provide more details on the ADC SOC(Start of Conversion) configuration?  - ACQPS, Trigger select, Reference used, input provided etc.
  • 0
    TI__Prodigy 230 points

    Hi Team,

     Could you please provide more information on below:

    1. What do Ch<x> mean?  Are you referring Ch as ADC SoC -> Ch7 means SoC7?  As I understand A4 is the external pin input which the customer is trying to sample.
    2. What is the trigger mode selected for these configurations? 
    3. Can you provide more details on the ADC SOC(Start of Conversion) configuration?  - ACQPS, Trigger select, Reference used, input provided etc.
  • 0 in reply to Srikanthan H
    TI__Expert 3081 points

    Hi Srikanthan,

    Thanks for replying, somehow I missed you reply eariler.

    1. Yes, Ch, means Soc "Are you referring Ch as ADC SoC -> Ch7 means SoC7" is correct.

    2&3 please see below syscfg screen shots

  • 0 in reply to Hang Yang
    TI__Expert 3081 points

    Hi Srikanthan,

    I shared the syscfg file else where.