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MSP430F47127: About ADCof MSP430F47127

Liu Yang
Expert 5915 points
Part Number: MSP430F47127

Hi Team,

Please help me answer the follow question, thank you so much.

We use four ADCs and take data about every 2ms, but sometimes data may loss (about once every several hours to several days). Shorting the AD input terminal does not improve it. Are there any possible solutions?

Best Regards,

Tom.Liu

  • 0
    TI__Genius 13215 points

    Hi Liu,

    Could you share me the details of your testing for this issue?

  • 0 in reply to Wei.Jetim Zhao
    TI__Expert 5915 points

    Hi Zhao,

    Below is the details about my question. Please give me some suggestions.

    I am using the MSP430F47127 microcontroller. The reference of ADC uses the built-in one. Before shorting the input pins of the ADC, the ADC reading was usually 3D2FH ± 2 or so, but it was possible to read in 3D3FH. Moreover, at another timing, the thing which was being read by 064Ah ± 4 was read at 024AH. When I tried to short the input pins of ADC, the thing which was being read by 7FD8H, was read at 07D8H. All of the conditions occur only once in about 1 to 3 days. The ADC reads once every 2 ms. The abnormal value is not always the same, but it seems that reading is wrong with 1 to 4 bits. Please teach us the cause of the symptom and how to handle it.

    Best Regards,

    Tom.Liu

  • 0 in reply to Liu Yang
    TI__Expert 5915 points

    Hi Wei,

    I wrote the details of our testing above.

    Can you give me some advice about it?

    Best Regards,

    Tom.Liu

  • 0 in reply to Liu Yang
    TI__Genius 13215 points

    Hi Liu,

    Why did you short the input pins of the ADC?

    What do you mean by "the thing which was being read by 064Ah ± 4 was read at 024AH."? I can't understand you description.

    I will be difficult to reproduce and debug your issue because you just find it in 1-3 days for one time. So I would suggest you to review your code configuration based on the Peripherals Example code and Users Guide firstly to make sure you have no issue for the SW and HW.

  • 0 in reply to Wei.Jetim Zhao
    TI__Expert 5915 points

    Hi Wei,

    Actually this question is from my customer so the reply is late.

    The reason for shorting the input terminal of AD is that the signal input to AD should be stable, but it should not be unstable due to noise and so on the way. For confirmation, I made a short circuit at the terminal of AD and confirmed. Because the value of AD still jumped suddenly, I judged that it was not the influence of the signal of the input. About once every 1 to 3 days, does it mean that even if the ADC data outputs an abnormal value, it is not abnormal?

    Best Regards,

    Tom.Liu

  • 0 in reply to Liu Yang
    TI__Expert 5915 points

    Hi Wei,

    I know you are very busy, but could you give me some advice about the question above?

    Thank you very much.

    Best Regards,
    Tom.Liu

  • 0 in reply to Liu Yang
    TI__Genius 13215 points

    Hi Liu,

    Did you do the suggestion I gave one week ago?

    I will be difficult to reproduce and debug your issue because you just find it in 1-3 days for one time. So I would suggest you to review your code configuration based on the Peripherals Example code and Users Guide firstly to make sure you have no issue for the SW and HW.

     

    What do you mean by "short the input terminal of AD" could you share me the schematic/layout you are using? 

    How do you "judged that it was not the influence of the signal of the input"? Did you scope the ADC input signal when the issue occurred?

  • 0 in reply to Wei.Jetim Zhao
    TI__Expert 5915 points

    Hi Wei,

    Thank you for your answer. I told my customer refer to the Peripherals Example code and Users Guide.

    The attached is the circuit diagram around the microcomputer from my customer.
    About the two place of the ad input, an abnormality occurred in the beginning without the remodeling, so cut and the short the input pins in order to remove the possibility of the abnormality of the peripheral circuit, but the symptom was not improved.

    Best Regards,
    Tom.Liu

  • 0 in reply to Liu Yang
    TI__Expert 5915 points

    Hi All,

    I know my question above is not easy to answer, but could anyone give me some advice?
    Thank you very much.

    Best Regards,
    Tom.Liu

  • 0 in reply to Liu Yang
    TI__Genius 13215 points

    Hi Tom,

    As noted in the device Datasheet, "It is recommended to short unused analog input pairs and connect them to analog ground (AVSS)". Did you connect the shorted pins to analog ground?

    Since the discussion is along for long time, I would encourage you to deeply learn the issue and device spec and then work with customer to do the basic test and reproducing for one time, for example the actions and questions I replied last time. It is difficult to give you any advise for the root cause or solution when no enough information/test results being given from you, not the question itself.

    Please do/answer below suggested action and question.

    I will be difficult to reproduce and debug your issue because you just find it in 1-3 days for one time. So I would suggest you to review your code configuration based on the Peripherals Example code and Users Guide firstly to make sure you have no issue for the SW and HW.

    How do you "judged that it was not the influence of the signal of the input"? Did you scope the ADC input signal when the issue occurred?

  • 0 in reply to Liu Yang
    TI__Genius 13215 points

    Hi Tom,

    As noted in the device Datasheet, "It is recommended to short unused analog input pairs and connect them to analog ground (AVSS)".  Did you connect the shorted pins to analog ground?

    Since the discussion is along for long time, I would encourage you to deeply learn the issue and device spec and then work with customer to do the basic test and reproducing for one time, for example the actions and questions I replied last time. It is difficult to give you any advise for the root cause or solution when no enough information/test results being given from you, not the question itself.

    Please do/answer below suggested action and question.

    I will be difficult to reproduce and debug your issue because you just find it in 1-3 days for one time. So I would suggest you to review your code configuration based on the Peripherals Example code and Users Guide firstly to make sure you have no issue for the SW and HW.

    How do you "judged that it was not the influence of the signal of the input"? Did you scope the ADC input signal when the issue occurred?

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