amp-hour meter

mAh-meter.ino

const uint32_t shuntMilliOhm = 10100;
const uint32_t refMilliVoltage = 1100;
const int sensorPin = A0;
const int updateIntervalMsec = 500;


void setup() {
    Serial.begin(9600);
    analogReference(INTERNAL);
    Serial.println("");
    Serial.println("Secs,ADC,mV,uA,(uAmsec),uAh,uAh/h");
}

uint32_t prev   = 0;
uint32_t uAmsec = 0;
uint32_t uAh= 0;
uint32_t lastStatusUpdate = 0;

void loop() {
    uint32_t now = micros();
    if (prev != 0) {
        uint32_t sensorValue = analogRead(sensorPin);
        uint32_t mV = refMilliVoltage * sensorValue / 1023UL;
        uint32_t uA = mV * 1000UL * 1000UL / shuntMilliOhm;

        uAmsec += uA * (now - prev) / 1000UL;

        if (uAmsec > 1000UL * 3600UL ) {
            uAh += uAmsec / (1000UL * 3600UL);
            uAmsec = uAmsec % (1000UL * 3600UL);
        }

        if (now - lastStatusUpdate > updateIntervalMsec * 1000UL) {
            Serial.print("\r                                                          \r");
            Serial.print(millis()/1000, DEC); Serial.print(",");
            Serial.print(sensorValue, DEC);   Serial.print(",");
            Serial.print(mV, DEC);            Serial.print(",");
            Serial.print(uA, DEC);            Serial.print(",");
            Serial.print(uAmsec, DEC);        Serial.print(",");
            Serial.print(uAh, DEC);           Serial.print(",");
            Serial.print(uAh*3600UL/(millis()/1000UL), DEC);
            lastStatusUpdate = now;
        }
    }
    prev = now;
    delay(1);
}

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