The Arduino UNO (and 328 clones) has the ability to report the rail voltage and temperature of the chip. You don’t need any additional wiring or sensors, just the Arduino itself. The temperature is not very accurate, and reports in Celcius, so we added a “adjustment” factor until it read room temperature, and converted to Fahrenheit. This is a fun “ok, I made it blink, now what” project.
Code
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void setup() { Serial.begin(9600);
}
void loop()
{
float volts = readVcc();
Serial.print(volts/1000);
Serial.println(” VDC”);
float temp = readTemp();
temp = temp/1000;
temp = temp + 25.7; //adjustment
temp = (temp * (9/5)) + 32; //conversion to fahrenheit
Serial.print(temp);
Serial.println(” F”);
delay(1000);
}
long readVcc() {
long result;
// Read 1.1V reference against AVcc
ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
delay(2); // Wait for Vref to settle
ADCSRA |= _BV(ADSC); // Convert
while (bit_is_set(ADCSRA,ADSC));
result = ADCL;
result |= ADCH<<8;
result = 1126400L / result; // Back-calculate AVcc in mV
return result;
}
long readTemp() {
long result;
// Read temperature sensor against 1.1V reference
ADMUX = _BV(REFS1) | _BV(REFS0) | _BV(MUX3);
delay(2); // Wait for Vref to settle
ADCSRA |= _BV(ADSC); // Convert
while (bit_is_set(ADCSRA,ADSC));
result = ADCL;
result |= ADCH<<8;
result = (result – 125) * 1075;
return result;
}
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