question about adc of msp430f5152

sry, in order to make my code short, i delete some code i thought that won't matter.

what should i do to make this work as i want.If a>0x1ff, 100 are selected. If a<0x1ff, and b y 0x1ff, 50 are seelcted, and if a<0x1ff but b>=0x1ff, 25 are seelcted.

here is all my code

void main(void)

{

volatile unsigned int i;

  WDTCTL = WDTPW+WDTHOLD;                  

// Stop WDT

  P1DIR |= BIT0;                           

// Set P1.0/LED to output direction

  P1DIR &= ~BIT1;                          

//Set P1.1 to input direction

  P1DIR &= ~BIT3;                          

//Set P1.3 to input direction

  P3DIR |= BIT6+BIT5 + BIT3+BIT4;;                      

// P3.6 and P3.5 output

  P3SEL |= BIT6+BIT5 + BIT3+BIT4;;                      

// P3.6 and P3.5 options select

  TA0CCR0 = 512-1;                         

// PWM Period

  TA0CCTL1 = OUTMOD_7;                     

// CCR1 reset/set

  TA0CCR1 = 0;

  TA0CCTL2 = OUTMOD_7;                     

// CCR2 reset/set

  TA0CCR2 = 0;                           

// CCR2 PWM duty cycle

  TA0CTL = TASSEL_2 + MC_1 + TACLR;        

// SMCLK, up mode, clear TAR

//UART setup   chapter 35

//P3SEL = BIT3+BIT4;                        // P3.3,4 = USCI_A0 TXD/RXD P3.3 sent out data, p3.4 recieve

  UCA0CTL1 |= UCSWRST;                     

// **Put state machine in reset**

  UCA0CTL1 |= UCSSEL_1;                    

// ACLK mode, PWM choose SMCLK, avoid conflict with it;

  UCA0BR0 = 6;                             

// Bit clock prescaler setting.  1MHz 9600 (see User's Guide)

  UCA0BR1 = 0;                             

// 1MHz 9600

  UCA0MCTL = UCBRS_0 + UCBRF_13 + UCOS16;  

// Modln UCBRSx=0, Second modulation stage select.

//UCBRFx=0 First modulation stage select.,

//UCOS16 over sampling enable

  UCA0CTL1 &= ~UCSWRST;                    

// Software reset enable. 0 Disabled.USCI reset released for operation.

  UCA0IE |= UCRXIE;                        

// Enable USCI_A0 RX interrupt
flag =0;

ADC_Result=0;

for(; ;){

a = adc(0);                      // get value from pin1

b = adc(2);                     // get value from pin2

if(a<0x1FF){

     if(b<0x1FF){

    pwm(50);}                   // duty cycle 50

    else

    pwm(25);

    }

else

pwm(100);

}

int ADC (char channel){

switch (channel){

case 0:

   // Configure ADC

    ADC10CTL0 |= ADC10SHT_5 + ADC10ON+ADC10MSC;       

// ADC10ON, S&H=1024 ADC clks
    ADC10CTL1 |= ADC10SHP+ADC10DIV_7+ADC10CONSEQ_2; 

// ADCCLK =SMCLK; sampling timer;

//clock divide by 8; single channel, Repeat-single-channel conversion;

    ADC10CTL2 |= ADC10RES;                   

// 10-bit conversion results

    ADC10IE |= ADC10IE0;

// Enable ADC conv complete interrupt
    ADC10MCTL0 |= ADC10INCH_1;               

// A1 ADC input select; Vref=AVCC

    ADC10CTL0 |= ADC10ENC + ADC10SC;       

// Sampling and conversion start

    __bis_SR_register(CPUOFF + GIE);       

// LPM0, ADC10_ISR will force exit

    ADC10CTL0 &= ~ADC10ENC;

    __no_operation();

// For debug only

break;

case 2:

// Configure ADC

ADC10CTL0 |= ADC10SHT_5 + ADC10ON+ADC10MSC;       

// ADC10ON, S&H=1024 ADC clks
ADC10CTL1 |= ADC10SHP+ADC10DIV_7+ADC10CONSEQ_2;

//ADCCLK =SMCLK; sampling timer; 

//clock divide by 8; single channel, Repeat-single-channel conversion;

ADC10CTL2 |= ADC10RES;                   

// 10-bit conversion results

ADC10IE |= ADC10IE0;                     

// Enable ADC conv complete interrupt

ADC10MCTL0 |= ADC10INCH_3;               

// A3 ADC input select; Vref=AVCC

ADC10CTL0 |= ADC10ENC + ADC10SC;       

// Sampling and conversion start

__bis_SR_register(CPUOFF + GIE);       

// LPM0, ADC10_ISR will force exit

ADC10CTL0 &= ~ADC10ENC;

__no_operation();

// For debug only 

break;

   } 

return ADC_Result;

}

// ADC10 interrupt service routine

#pragma vector=ADC10_VECTOR

__interrupt void ADC10_ISR(void)

{

//static unsigned char index = 0;

switch(__even_in_range(ADC10IV,12))

  {

case  0: break;                          // No interrupt

case  2: break;                          // conversion result overflow 

case  4: break;                          // conversion time overflow

case  6: break;                          // ADC10HI   

case  8: break;                          // ADC10LO

case 10: break;                          // ADC10IN

case 12:

             ADC_Result= ADC10MEM0;

             __bic_SR_register_on_exit(CPUOFF);

break;                          // Clear CPUOFF bit from 0(SR)

default: break;

  }

}

void PWM(int value)

{

TA0CCR1 = value;

TA0CCR2 = value;

}

renhai zhou said:

ADC10MCTL0 |= ADC10INCH_3; 

About settign the PWM, you must synchronize the settign of the PWM DC with the cycle of th etimer. One possible way is to writ ethe intended value into two global variables, and let CCR0 trigger an interrupt. Inside the ISR, which is called when TAR counts to CCR0 and then overflows, you write the global variables to CCR1/2. THis way, you change the DC at the beginning of a cycle and you have 25% of a cycle for doing so. If you fail to do it in time, you'll have an overlong or underlong cycle. But at least aren't you changing the DC anywhere, e.g. producing additional PWm edges. The TiemrB has means to do the synchronization in hardware, so your code would be perfectly okay.
However, even for TImerA it isn't as bad as I feared - you could have restarted or cleared the timer on each reprogramming ;)

However, if value is the intended duty cycle, then it must be multiplied with the CCR0 count factor. The values you write are timer ticks, not percent. currently, the oputput changes state at timer tick #25,50 or 100. Not on 25/50/100% of the full cycle, so use 128, 256 and 512 for 25, 50 and 100%. And use OUTMOD_3, which is suited for DC of >0 to 100%, while OUTMOD7 is for DC of 0 to <100%. You cannot easily have a DC range which includes both, 0% and 100%, as the MSP cannot determine beginning from end of a circle :)
Well, technically, neither 0% nor 100% form a 'valid' PWM as both have 0Hz frequency.