adc.c

Go to the documentation of this file.

#include <math.h>
#include "adc.h"
#if INC_TSEND_INIT == 0
  #include "setup.h"
#endif

UINT g_adcData[ADC_INPUTS];
UCHAR volatile g_adcConverting = FALSE;
UCHAR volatile g_justMuxed = FALSE;

void AdcInit(void) {
  // ADC initialization
  // ADC Voltage Reference: AVCC pin
  SetMux(FIRST_ADC_INPUT);

//  ADCSRA - ADC Control and Status Register A
//    | ADEN [1] | ADSC [1] | ADATE [0] | ADIF [0] | ADIE [1] | ADPS2 [0] | ADPS1 [1] | ADPS0 [1] |
//    ADEN  <- enable ADC
//    ADSC  <- start conversion immediately to consumpt the initial 25 ADC cycles
//    ADIE  <- enable ADC interrupt
//    ADPSn <- prescaler source clock 8MHz / 64 = 125KHz
  ADC_SR = (1<<ADEN) | (1<<ADSC) | (0<<AD_FR) | (0<<ADIF) | (1<<ADIE) | (1<<ADPS2) | (1<<ADPS1) | (0<<ADPS0);
}

ISR(ADC_vect) {
  static UCHAR id=0, meanCnt=0;
  
  //terminate if nothing to do
  if(!g_adcConverting)
    return;
  //throw away the conversion result if MUX just switched
  if(! g_justMuxed) {
    //read AD conversion result
    g_adcData[id] += ADCW;
    // Select next ADC input
    if(++meanCnt > ADC_MEAN_VALUES)
    {
      meanCnt = 0;
      if(++id >= ADC_INPUTS)
      {
        id=0;
        SetMux(id);
        //converting should evaluate to FALSE @ this point
        g_adcConverting = FALSE;
        return;
      }
      SetMux(id);
    }
  }
  else
    g_justMuxed = FALSE;
  StartAdcConversion();
}

void ProcessNextConversion(void) {
  //all results processed?
  if(g_adcData[ADC_TMP_INNER_ID] == INVALID_VAL_U16 && g_adcData[ADC_TMP_OUTER_ID] == INVALID_VAL_U16
#if INC_TSEND_INIT == 1
      && g_adcData[ADC_SUPP_VOLT_ID] == INVALID_VAL_U16
#endif
    )
    StartAdcConversion();
}

void StartAdcConversion(void) {
  g_adcConverting = TRUE;
  //effectively start conversion
  ADC_SR |= (1<<ADSC);
}

void SetMux(UCHAR ch) {
  ADMUX = (FIRST_ADC_INPUT | ADC_VREF_SEL) + ch;
  g_justMuxed = TRUE;
}

UINT CalcAdcTemp(UCHAR id) {
  UINT res = g_adcData[id];
  float rohm = 0.0, div = 0.0;
  
  //do nothing if in conversion progress
  if(g_adcConverting)
    return INVALID_VAL_U16;
  g_adcData[id] = INVALID_VAL_U16;
  ProcessNextConversion();
#if INC_TSEND_INIT == 0
  rohm = (float)((((float)(((float)((float)res / (float)ADC_MEAN_VALUES)) * (float)gArv())) / (float)ADC_RES)) * (float)gRcv();
  div = log(rohm/(float)gRri());
#elif INC_TSEND_INIT == 1
  rohm = (float)((((float)(((float)((float)res / (float)ADC_MEAN_VALUES)) * (float)ADC_REF_VOLTAGE)) / (float)ADC_RES)) * (float)REV_CURRENT_VALUE;
  div = log(rohm/(id == ADC_TMP_INNER_ID ? (float)RR_IN : (float)RR_OUT));
#endif
  return (UINT)(((1/(A1 + B1*div + C1*pow(div,2) + D1*pow(div,3))) - 273.15) * 1000.0);
}

UINT CalcSupplyVoltage(UCHAR id) {
  UINT res = g_adcData[id];

  //do nothing if in conversion progress
  if(g_adcConverting)
    return INVALID_VAL_U16;
  g_adcData[id] = INVALID_VAL_U16;
  ProcessNextConversion();
//  return res;
  return (UINT)(((float)(((float)res / (float)ADC_MEAN_VALUES) * (float)ADC_REF_VOLTAGE) / (float)ADC_RES) * ADC_SUP_DIV_FCT);
}