2-Series temperature sensor

[mechatroniks-git]

I took a stab at reading the internal temp sensor, and it appears to work, sharing here.

uint16_t readTemp() {
  volatile uint16_t adc_reading;
  uint8_t sigrow_gain = SIGROW.TEMPSENSE0;
  int8_t sigrow_offset = SIGROW.TEMPSENSE1;
  uint32_t temp;

  //ATtiny1624/1626/1627 datasheet section 30.3.3.7 Temperature Measurement
  //1. Configure the voltage reference to internal 1.024V by writing to the Reference Selection (REFSEL) bit field the ADCn.CTRLC register.
  analogReference(INTERNAL1V024);

  //2.  Select the temperature sensor as input in the Positive Input Multiplexer (ADCn.MUXPOS) register.
  ADC0.MUXPOS = ADC_MUXPOS_TEMPSENSE_gc;

  //3. Configure the ADC Sample Duration by writing a value ≥ 32 µs × CLK_ADC to the Sample Duration (SAMPDUR) bit field in the Control E (ADCn.CTRLE) register
  analogSampleDuration(50); 

  //4.  Acquire the temperature sensor output voltage by running a 12-bit Single-Ended conversion.
  adc_reading = analogRead(ADC_TEMPERATURE);

  //5.  Process the measurement result, as described in datasheet, except the offset is added, not subtracted
  temp = (uint32_t)adc_reading + sigrow_offset;
  temp *= sigrow_gain;
  temp += 0x80;
  temp >>= 8;

  //Serial.printf("K=%d\n", temp);
  //Serial.printf("C=%d\n", temp - 273);
  //Serial.printf("F=%d\n", (((temp - 273) * 9) / 5) + 32);

  return (uint16_t)(temp & 0xFFFF);
}

Also, the example was showing 334mV for the supply voltage, so I scale by 10 to get 3340mV, closer to actual.

uint16_t readSupplyVoltage() { //returns value in millivolts to avoid floating point
  analogReference(INTERNAL1V024);
  int32_t vddmeasure = analogReadEnh(ADC_VDDDIV10, 12); // Take it at 12 bits & discard
  vddmeasure = analogReadEnh(ADC_VDDDIV10, 12); // Take it at 12 bits
  return ((vddmeasure * 5 ) >> 1 ); Multiply by 10 and divide by 4
}

[mechatroniks-git]

Another way to do it: https://gist.github.com/greasemonkey-btbm/190ffec9884e512712ba2ba9e4c1473e#file-attiny824-read-temperature-ino

[SpenceKonde]

Issue created, this is clearly a bug in the example and needs to be tracked as such.