Other Parts Discussed in Thread: MSP430G2955
Hi..
We have started our development using MSP430G2955 ,we have six anolog signals and we try to sample and accumulate the count using ADC10.The sampling rate is 625 uSec and the maximum sample count is 2000 samples. We used the 2.5v Vreference and the signal level for ADC channel is 0.68V at full voltage (290VAC )/at full current (5A) . when we apply the full voltage (290VAC) then we didn’t get the expected output but upto 120VAC we got the approx 120VAC. This behavior is same for the current, when we apply the full current (5A) then we didn’t get the expected output but upto 2.32A we got the approx value though ADC measurement.
We have tried the same code on both CCS5.4 & IAR compiler and we also cross checked our hardware but there is no issue in our hardware .
In watch sometime we have observed the value of isquare_temp variable and value of isq_sum_v1 variable get truncated but both the variables are unsigned int long long and by actual calculation our value after squared and accumalated the 2000 samples ( if we consider the max value of v1_current_sample=511 and max samples =2000) is 522242000 which is within the limit of unsined int long long.
Example:
full signal level ADC is 1023 .
LSHIFT=512;
v1_current_sample=1023-512; ……….. ( v1_current_sample=v1_current_sample-LSHIFT)
v1_current_sample=511;
isquare_temp=(511*511);
isq_sum_v1+= isquare_temp; ( addition is 2000 times becauseour max sample count is 2000)
Pl refer the below code and kindly help to resolved our query .
///////////////////////////////////////////////////////////////////////// code
///////////////////////////////////////// variable definition in main
# define MAX_ADC_SAMPLE_COUNT 2000
unsigned int long long isquare_temp=0;
unsigned int long long isq_sum_v1=0;
unsigned int long long isq_sum_v2=0;
unsigned int long long isq_sum_i2=0;
unsigned int long long isq_sum_v3=0;
unsigned int long long isq_sum_i3=0;
unsigned int long long isq_sum_i1=0;
signed int i1_current_sample;
signed int i1_old_sample;
signed int i2_old_sample;
signed int i3_old_sample;
signed int v1_current_sample;
signed int v2_current_sample;
signed int v3_current_sample;
//////////////////////////////////////////////////////////////////////////
Note: first we Turn on the ADC in main
//////////////////////////////////
#pragma vector=ADC10_VECTOR
__interrupt void ADC10_ISR (void)
{
Sample_counter++;
v1_current_sample=ADCbuf[2];// voltage Vr samples
v2_current_sample=ADCbuf[3];// voltage Vy samples
v3_current_sample=ADCbuf[1];// voltage Vb samples
i1_current_sample=ADCbuf[8];// current Ir samples;
i2_current_sample=ADCbuf[9];// current Iysamples;
i3_current_sample=ADCbuf[0];// current Ib samples;
////////////////////////////////////////////////////////////////
LSHIFT=512;
///////////////////////////////////////////////Remove Dc/////////////////////////
v1_current_sample=v1_current_sample-LSHIFT;
v2_current_sample=v2_current_sample-LSHIFT;
v3_current_sample=v3_current_sample-LSHIFT;
i1_current_sample=i1_current_sample-LSHIFT;
i2_current_sample=i2_current_sample-LSHIFT;
i3_current_sample=i3_current_sample-LSHIFT;
i2_current_sample=-i2_current_sample;
/////////////////////////////////////////////////// square
isquare_temp=(unsigned int long long ) (v1_current_sample*v1_current_sample);
isq_sum_v1+=isquare_temp;
isquare_temp=(unsigned int long long ) (v2_current_sample*v2_current_sample);
isq_sum_v2+=isquare_temp;
isquare_temp=(unsigned int long long ) (v3_current_sample*v3_current_sample);
isq_sum_v3+=isquare_temp;
isquare_temp=(unsigned int long long ) (v1_current_sample-v2_current_sample)*(v1_current_sample-v2_current_sample);
isq_sum_v12+=isquare_temp;
isquare_temp=(unsigned int long long ) (v3_current_sample-v2_current_sample)*(v3_current_sample-v2_current_sample);
isq_sum_v32+=isquare_temp;
isquare_temp=(unsigned int long long ) (v3_current_sample-v1_current_sample)*(v3_current_sample-v1_current_sample);
isq_sum_v31+=isquare_temp;
isquare_temp = (unsigned int long long)((i1_current_sample)*(i1_current_sample));
isq_sum_i1+=isquare_temp;
isquare_temp=(unsigned int long long )((i2_current_sample)*(i2_current_sample));
isq_sum_i2+=isquare_temp;
isquare_temp=(unsigned int long long )((i3_current_sample)*(i3_current_sample));
isq_sum_i3+=isquare_temp;
isquare_temp=(unsigned int long long )((i2_current_sample)*(i2_current_sample));
isq_sum_i2+=isquare_temp;
isquare_temp=(unsigned int long long )((i3_current_sample)*(i3_current_sample));
isq_sum_i3+=isquare_temp;
ADC10CTL0 &=~ENC; // disable conversions
__no_operation();
ADC10CTL0 |=ENC; // Enable conversions
If (isample_counter==(MAX_ADC_SAMPLE_COUNT))//MAx count
{
TA0CCR0=0; //remember to make ADC timer off
// Note : we again turn ON this ADC timer in main after done the processing on accumalted samples
}
}
