jappelino

To make things easy the measurements are based on 1 bit equals 100 mA, this is equal to measure 1 mV over the 10 mOhm measurent resistor. The AD converter is run in a one shot mode, this might be improved with a interrupt version which probably will decrease the average current consumption slightly.

After the conversion is finished the result is scaled to acomplish the 1bit/100mA approach. The scaled sample is added to a sum for later calculation of the amp hours, there is also a value saved to show the max current.

void ad_3(void){

  int status = 0;

  int i; CCTL0 = OUT;                                              // TXD Idle as Mark

  TACTL = TASSEL_1 + MC_2;                            // ACLK, Continuous mode 

  BCSCTL2 |= DIVS_3; // SMCLK/8

  SD16CTL = SD16REFON + SD16SSEL_1;   // Use 1.2V ref,

  SMCLK SD16CCTL0 = SD16DF;                     // twos complement

  SD16INCTL0 = SD16INCH_2;                         // SD16 A2+/- pin 6 & 7

  SD16AE = SD16AE4 + SD16AE5;                   // A2+ and A2-

  for(i=0; i<3600; i++);

  SD16CCTL0 |= SD16SNGL;                            // Single conversion

  SD16CCTL0 |= SD16SC;                                 // Start conversion

  while((status & SD16IFG) == 0)
      status = SD16CCTL0;                                  // Wait until ready

  sampleData = SD16MEM0;                             // Read the sample

  if(sampleData < 0)
      sampleData = -sampleData;

  SD16CTL = 0; // set reference off

  SD16AE = 0; // disable inputs

  scale();

  sum_sample();

  if(sample_scaled > sample_max)
        sample_max = sample_scaled;

}
 
void scale(void){

  unsigned int sample;

  sample = sampleData;

  sample = sample * scale_mult;                 // be careful to multiply first not to lose small values

  sample = sample / scale_div;

  sample_scaled = sample;

}

void sum_sample(void){

    sum += sample_scaled;

}