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CCS/MSP430FR5739: Wrong ADC10 results in the memory

Volker Dworak
Prodigy 175 points
Part Number: MSP430FR5739
Other Parts Discussed in Thread: MSP-EXP430FR5739

Tool/software: Code Composer Studio

Dear Community,

I use nearly the software example from the demo code:

CCS8.2/MSP430FR5739/DMA(64)-ADC10

And I like the use of nearly the full 16Bit room (64*1023=65472) and no overflow should happen.

The point is, overflow happens many times and looking at the register values explains this.

For example: ADC10result[20] = 7651. How can the ADC10 Module generate values higher like 1023?

Can someone give me a hint?

Sincerely

Volker

  • 0
    TI__Intellectual 985 points

    Hi Volker,

    could you please share your code, that we could have a look at the problem.

  • 0 in reply to Peter Weber
    Prodigy 175 points

    Here  is the part of the ADC code:

    unsigned int ADC_Result[64];
    unsigned int k;
    unsigned int ADC_Result_sum;

      // Configure ADC10 - pulse sample mode; software trigger;
      ADC10CTL0 = ADC10SHT_2 + ADC10ON + ADC10MSC; // 16ADCclks, ADC on
      ADC10CTL1 = ADC10SHP + ADC10CONSEQ_2;     // pulse sample mode, rpt single ch
      ADC10CTL2 = ADC10RES;                     // 10-bits of resolution
    //  ADC10MCTL0 = ADC10INCH_1;                 // AVCC ref, A1
      ADC10HI = 950;                 // Window Comparator Hi-threshold
      ADC10LO = 75;                  // Window Comparator Lo-threshold

      // Configure DMA (ADC10IFG trigger)
      DMACTL0 = DMA0TSEL__ADC10IFG;                     // ADC10IFG trigger
      __data16_write_addr((unsigned short) &DMA0SA,(unsigned long) &ADC10MEM0);
                                                // Source single address
      __data16_write_addr((unsigned short) &DMA0DA,(unsigned long) &ADC_Result[0]);
                                                // Destination array address
      DMA0SZ = 66;                              // 64 conversions
      // Rpt, inc dest, word access,
      DMA0CTL = DMADT_4 + DMADSTINCR_3 + DMAEN + DMAIE + DMALEVEL;
                                             // enable int after 66 conversions


    // In while loop:

    if (DMA64ISR)
          {
              ADC_Result_sum = 0x0;                   // clear accumulate register
              for(k=2;k<66;k++) {                      // BREAKPOINT HERE; View ADC_Result
              ADC_Result_sum += ADC_Result[k];
              }
              DMA64ISR = 0;
              sumreddy = 1;
          }
    if (ADCSW)
          {
              DMA0CTL |=DMAEN + DMAIE;   // DMA-ADC-Routine
              ADC10CTL0 |= ADC10ENC + ADC10SC;        // Sampling and conversion start
              ADCSW = 0;
          }

    // Call in UART - fuction example:

    else if ((c_Befehl[1]=='I') | (c_Befehl[1]=='i'))
        {

        //Auslesen des Motorstroms
        ADC10CTL0 &= ~ADC10ENC;
        ADC10MCTL0 = ADC10INCH_13;                 // AVCC ref, A13
        ADC = 13;
        ADCSW = 1;
        return;
        }

    // Part in the IRQ :


    #if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
    #pragma vector=DMA_VECTOR
    __interrupt void DMA0_ISR (void)
    #elif defined(__GNUC__)
    void __attribute__ ((interrupt(DMA_VECTOR))) DMA0_ISR (void)
    #else
    #error Compiler not supported!
    #endif
    {
      switch(__even_in_range(DMAIV,16))
      {
        case  0: break;                          // No interrupt
        case  2:
          // 64 conversions complete
          ADC10CTL0 &= ~ADC10ENC;
          DMA64ISR = 1;     // start sum
          break;                                 // DMA0IFG
        case  4: break;                          // DMA1IFG
        case  6: break;                          // DMA2IFG
        case  8: break;                          // Reserved
        case 10: break;                          // Reserved
        case 12: break;                          // Reserved
        case 14: break;                          // Reserved
        case 16: break;                          // Reserved
        default: break;
      }
    }

  • 0 in reply to Volker Dworak
    TI__Genius 13215 points

    Hi Volker,

    Sorry for reply late.

    I reviewed your code and found you declared the ADC_Result[64] for unsigned int type(16 bit by default). But you changed the type to unsigned long(32 bit by default) in the DMA configuration. You may change your declaration of ADC_Result[64] to unsigned long(32 bit) which aligns with your code in DMA part. Please let me know your test result after updating the declaration.

    BTW, I have tried you code on MSP-EXP430FR5739 and it showed no ADC result out of 0x3FF.

  • 0 in reply to Wei.Jetim Zhao
    Prodigy 175 points

    Hi thank you very much for answering,

    I just have copied the DMA example (without understanding the code ;-) ) and they are using it in the same way.

    I will try and give you feedback

    Volker

  • 0 in reply to Volker Dworak
    TI__Genius 13215 points
    Hi Volker,

    Thanks for reply. Please feel free to come back when you get any update.

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