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Using the RJ12 for luminosity, temperature and power supply

The default connector as the following pin out

  • +12V (not connected)
  • SCL (PWM)
  • SDA (I/O)
  • A6 (GND)
  • +5V
  • GND

There is the possiblity to have an internal pullup so that if we connect a LDR between the ground and A6 it should be possible to measure the light intensity.

We can also connect a one-wire temperature probe DS18B20 connected to SCL. We will also have to connect a 4.7kΩ between +5V and SCL.

Finally we can connect the power supply between the +5V and the GND. The power supply may be anything between 3.7 and 6V.