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CCS/MSP430FR5857: ADC12 in Repeat Autoscan mode.

Part Number: MSP430FR5857
Other Parts Discussed in Thread: MSPWARE

Tool/software: Code Composer Studio

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 *                       MSP430 CODE EXAMPLE DISCLAIMER
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 * MSP430 code examples are self-contained low-level programs that typically
 * demonstrate a single peripheral function or device feature in a highly
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 * register values and settings such as the clock configuration and care must
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//******************************************************************************
//  MSP430FR59xx Demo - ADC12, Sample A1, AVcc Ref, Set P1.0 if A1 > 0.5*AVcc
//
//   Description: A single sample is made on A1 with reference to AVcc.
//   Software sets ADC12SC to start sample and conversion - ADC12SC
//   automatically cleared at EOC. ADC12 internal oscillator times sample (16x)
//   and conversion. In Mainloop MSP430 waits in LPM0 to save power until ADC12
//   conversion complete, ADC12_ISR will force exit from LPM0 in Mainloop on
//   reti. If A1 > 0.5*AVcc, P1.0 set, else reset. The full, correct handling of
//   and ADC12 interrupt is shown as well.
//
//
//                MSP430FR5969
//             -----------------
//         /|\|              XIN|-
//          | |                 |
//          --|RST          XOUT|-
//            |                 |
//        >---|P1.1/A1      P1.0|-->LED
//
//   T. Witt / P. Thanigai
//   Texas Instruments Inc.
//   November 2013
//   Built with IAR Embedded Workbench V5.60 & Code Composer Studio V5.5
//******************************************************************************
#include <msp430.h>

int main(void)
{
  WDTCTL = WDTPW | WDTHOLD;                 // Stop WDT

  // GPIO Setup
  P2OUT &= ~BIT2;                           // Clear LED to start
  P2DIR |= BIT2;                            // Set P1.0/LED to output
  P3OUT &= ~BIT7;                           // Clear LED to start
  P3DIR |= BIT7;
  P1SEL1 = BIT0|BIT1;                           // Configure P1.1 for ADC
  P1SEL0 = BIT0|BIT1;

  // Disable the GPIO power-on default high-impedance mode to activate
  // previously configured port settings
  PM5CTL0 &= ~LOCKLPM5;

  // Configure ADC12
  ADC12CTL0 = ADC12SHT0_2 | ADC12ON| ADC12MSC;        // Sampling time, S&H=16, ADC12 on
  ADC12CTL1 = ADC12SHP| ADC12CONSEQ_3;                     // Use sampling timer
  ADC12CTL2 |= ADC12RES_2;                  // 12-bit conversion results
  ADC12MCTL0 |= ADC12INCH_0;                // A1 ADC input select; Vref=AVCC
  ADC12MCTL1 = ADC12INCH_1|ADC12EOS;                // A1 ADC input select; Vref=AVCC
  ADC12IER0 = ADC12IE0| ADC12IE1;                    // Enable ADC conv complete interrupt

  ADC12CTL0 |= ADC12ENC | ADC12SC;        // Start sampling/conversion
  while (1)
  {
  /*  __delay_cycles(5000);
    ADC12CTL0 |= ADC12ENC | ADC12SC;        // Start sampling/conversion

    __bis_SR_register(LPM0_bits | GIE);     // LPM0, ADC12_ISR will force exit
    __no_operation();                       // For debugger */
  }
}

#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector = ADC12_VECTOR
__interrupt void ADC12_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(ADC12_VECTOR))) ADC12_ISR (void)
#else
#error Compiler not supported!
#endif
{
  switch(__even_in_range(ADC12IV, ADC12IV_ADC12RDYIFG))
  {
    case ADC12IV_NONE:        break;        // Vector  0:  No interrupt
    case ADC12IV_ADC12OVIFG:  break;        // Vector  2:  ADC12MEMx Overflow
    case ADC12IV_ADC12TOVIFG: break;        // Vector  4:  Conversion time overflow
    case ADC12IV_ADC12HIIFG:  break;        // Vector  6:  ADC12BHI
    case ADC12IV_ADC12LOIFG:  break;        // Vector  8:  ADC12BLO
    case ADC12IV_ADC12INIFG:  break;        // Vector 10:  ADC12BIN
    case ADC12IV_ADC12IFG0:                 // Vector 12:  ADC12MEM0 Interrupt
      if (ADC12MEM0 >= 0x7ff)               // ADC12MEM0 = A1 > 0.5AVcc?
        P2OUT |= BIT2;                      // P1.0 = 1
      else
        P2OUT &= ~BIT2;                     // P1.0 = 0
      __bic_SR_register_on_exit(LPM0_bits); // Exit active CPU
      break;                                // Clear CPUOFF bit from 0(SR)
    case ADC12IV_ADC12IFG1:                 // Vector 14:  ADC12MEM1
        if (ADC12MEM1 >= 0x7ff)               // ADC12MEM0 = A1 > 0.5AVcc?
          P3OUT |= BIT7;                      // P1.0 = 1
        else
          P3OUT &= ~BIT7;                     // P1.0 = 0
        __bic_SR_register_on_exit(LPM0_bits); // Exit active CPU
        break;
    case ADC12IV_ADC12IFG2:   break;        // Vector 16:  ADC12MEM2
    case ADC12IV_ADC12IFG3:   break;        // Vector 18:  ADC12MEM3
    case ADC12IV_ADC12IFG4:   break;        // Vector 20:  ADC12MEM4
    case ADC12IV_ADC12IFG5:   break;        // Vector 22:  ADC12MEM5
    case ADC12IV_ADC12IFG6:   break;        // Vector 24:  ADC12MEM6
    case ADC12IV_ADC12IFG7:   break;        // Vector 26:  ADC12MEM7
    case ADC12IV_ADC12IFG8:   break;        // Vector 28:  ADC12MEM8
    case ADC12IV_ADC12IFG9:   break;        // Vector 30:  ADC12MEM9
    case ADC12IV_ADC12IFG10:  break;        // Vector 32:  ADC12MEM10
    case ADC12IV_ADC12IFG11:  break;        // Vector 34:  ADC12MEM11
    case ADC12IV_ADC12IFG12:  break;        // Vector 36:  ADC12MEM12
    case ADC12IV_ADC12IFG13:  break;        // Vector 38:  ADC12MEM13
    case ADC12IV_ADC12IFG14:  break;        // Vector 40:  ADC12MEM14
    case ADC12IV_ADC12IFG15:  break;        // Vector 42:  ADC12MEM15
    case ADC12IV_ADC12IFG16:  break;        // Vector 44:  ADC12MEM16
    case ADC12IV_ADC12IFG17:  break;        // Vector 46:  ADC12MEM17
    case ADC12IV_ADC12IFG18:  break;        // Vector 48:  ADC12MEM18
    case ADC12IV_ADC12IFG19:  break;        // Vector 50:  ADC12MEM19
    case ADC12IV_ADC12IFG20:  break;        // Vector 52:  ADC12MEM20
    case ADC12IV_ADC12IFG21:  break;        // Vector 54:  ADC12MEM21
    case ADC12IV_ADC12IFG22:  break;        // Vector 56:  ADC12MEM22
    case ADC12IV_ADC12IFG23:  break;        // Vector 58:  ADC12MEM23
    case ADC12IV_ADC12IFG24:  break;        // Vector 60:  ADC12MEM24
    case ADC12IV_ADC12IFG25:  break;        // Vector 62:  ADC12MEM25
    case ADC12IV_ADC12IFG26:  break;        // Vector 64:  ADC12MEM26
    case ADC12IV_ADC12IFG27:  break;        // Vector 66:  ADC12MEM27
    case ADC12IV_ADC12IFG28:  break;        // Vector 68:  ADC12MEM28
    case ADC12IV_ADC12IFG29:  break;        // Vector 70:  ADC12MEM29
    case ADC12IV_ADC12IFG30:  break;        // Vector 72:  ADC12MEM30
    case ADC12IV_ADC12IFG31:  break;        // Vector 74:  ADC12MEM31
    case ADC12IV_ADC12RDYIFG: break;        // Vector 76:  ADC12RDY
    default: break;
  }
}

Given above is the code I edited from the examples given in MSPWare. I tried the Autoscan mode(sequence of channels) and it was working but the Repeat Autoscan( repeat a sequence of channels)  code aboe is not working. Help me with what I have done wrong.

  • What is it that is not working?

    As I read this: With ADC12SHT_2, each conversion takes 16+13+1=30 ADC clocks. As I recall, at startup MCLK is ~1MHz and MODOSC (ADC12SSEL_0) is ~5MHz, so that is 30/5=6 CPU cycles, or about two CPU instructions, between interrupts. You should probably budget at least 30 CPU instructions just to get into/out of the ISR.

    In short: the ADC is giving you data much(!) faster than you can process it. Since ADC12IV_ADC12IFG0 has higher priority, you'll only (ever) process the channel A0 data, so I expect it looks like A1 isn't working. If so, the solution is to slow down the ADC, either (a) a slower clock (ACLK?) or (b) go back to CONSEQ=1 and pace it using software or a timer trigger (ADC12SHS).

    But that's just me. It's probably best if you describe what's not working.

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