Hello Sir,
Iam trying to use Sigma Delta ADC of MSP430fg479 -I set the SD16 in Biploar mode,gain is 32 and my input range is 0.02mV DC to 6mv DC (using load cell
of 40Kg with 3volt supply and 2mv/v sensitivity)but SD16Result ultimatelely SD16MEM0 results are not consistent some times I get very good results and sometimes random like getting 65550 integer count (SD!^MEM0)although it is set in Bipolar mode.
#include <msp430fg479.h>
long SD16Temp; // Temp sum register
long SD16Result;
#define Num_of_Results 256
/* Arrays to store SD16_A conversion results */
unsigned int results[Num_of_Results];
int main(void)
{
volatile unsigned int i; // Use volatile to prevent removal
// by compiler optimization
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
FLL_CTL0 |= XCAP14PF; // Configure load caps
P6SEL |= BIT0+BIT1; // Config SD16 inputs
for (i = 0; i < 10000; i++); // Delay for 32 kHz crystal to
// stabilize
SD16CTL = SD16REFON+SD16SSEL0; // 1.2V ref, SMCLK
SD16INCTL0 |= SD16INTDLY_0+SD16GAIN_32; // Interrupt on 4th sample
SD16CCTL0 |= SD16IE+SD16DF+SD16OSR_1024; // Enable interrupt
for (i = 0; i < 0x3600; i++); // Delay for 1.2V ref startup
SD16CCTL0 |= SD16SC; // Set bit to start conversion
__bis_SR_register(LPM0_bits+GIE); // Enter LPM0
}
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=SD16A_VECTOR
__interrupt void SD16ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(SD16A_VECTOR))) SD16ISR (void)
#else
#error Compiler not supported!
#endif
{
static unsigned int index = 0;
switch (SD16IV)
{
case 2: // SD16MEM Overflow
break;
case 4: // SD16MEM0 IFG
results[index] = SD16MEM0; // Save CH0 results (clears IFG)
if (++index == Num_of_Results)
{SD16Temp=0;
SD16Result=0;
for(int i=0;i<Num_of_Results;i++)
{ SD16Temp += results[i];}
SD16Result = SD16Temp >> 8;
index = 0; // SET BREAKPOINT HERE
}
break;
}
}
Thank You,
Looking forward to your reply as it very urgent
Ujwala
