Terkin: system.temperature weird values

Thias · December 16, 2019, 9:11am

system.temperature always returns implausible values, like

Log:
system.temperature 12.6087

and Dashboard. The peaks in system.temperature are from times when I developed with the board.

Shouldn’t machine.temparature() return values in Fahrenheit and where is this formula from?

hiveeyes/terkin-datalogger/blob/61713c788cec43ed21640feddfa828bc287f22ca/terkin/sensor/system.py#L65


      
                                                'not implemented on this platform')
          
                  rawvalue = machine.temperature()
          
                  # Fahrenheit
                  # 'system.temperature': 57.77778
                  #temperature = (rawvalue - 32) / 1.8
          
                  # Magic
                  # 'system.temperature': 41.30435
                  value = rawvalue * (44/23) + (-5034/23)
          
                  reading = {'system.temperature': value}
                  return reading
          
          
          class SystemBatteryLevel(AbstractSystemSensor):
              """
              Read the battery level by sampling the ADC on a pin connected
              to a voltage divider. As the Pycom expansion board is using
              Pin 16, this is also used on other boards as kind of a convention.

According to the latest comment here:

temp sensor feature is no longer supported

Is this related?

poesel · December 16, 2019, 11:22am

Espressif removed the internal temperature sensors from the newer ESP32s. The measurement was just too unreliable.
I don’t know how many chips Pycom has on stock but eventually they will have to drop support for it, too. So we can’t rely on it either.

Thias · December 16, 2019, 11:41am

Thanks. So, I’ll skip the reading in Terkin

Andreas · December 16, 2019, 4:48pm

This is coming from esp32: Add temperature reading. by ticpu · Pull Request #3933 · micropython/micropython · GitHub.

However, it looks like the ESP32-S2 still supports it, see Page Not Found - ESP32 - — ESP-IDF Programming Guide latest documentation.