Power Pins

The sensor on the breakout requires between a 2.7V and 5.5V, and can be easily used with most microcontrollers from an Arduino to a Feather or something else.

  • Vcc - this is the power pin.  To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V micro like Arduino, use 5V
  • GND - common ground for power and logic

I2C Logic Pins

  • SCL - I2C clock pin, connect to your microcontrollers I2C clock line. The logic level is the same as Vcc and it has a 10K pullup already on it.
  • SDA - I2C data pin, connect to your microcontrollers I2C data line. The logic level is the same as Vcc. and it has a 10K pullup already on it.
  • STEMMA QT - These connectors allow you to connectors to dev boards with STEMMA QT connectors or to other things with various associated accessories

Resistor Pins

  • RW is the wiper of the potentiometer. As the wiper value is adjusted via I2C, the resistance between RW and GND changes 
  • RH is the High Terminal of the potentiometer, often connected to your high voltage source. The DS1841 has a fixed resistor between RH and RW which forms a voltage divider when RH is connected to VCC, with the voltage between RW and GND varying with the wiper setting

Extra Pins

  • A0 and A1 - These are the address select pins which set the two least significant bits of the I2C address. The are pulled to GND with two resistors which sets the address to 0x28 by default.

Adjusting the I2C Address

The default address is 0x28 and the address can be calculated by 'adding' the A0/A1 to the base of 0x28. You can change the values of one or both A0 and A1 by bridging the solder jumpers on the back of the board with solder. You can also set A0 or A1 by using a jumper wire to connect them to Vcc.

A0 sets the lowest bit with a value of 1, and A1 sets the next highest bit that has a value of 2. The final address is 0x28 + A1 + A0.

  • For example if only A0 is tied to Vcc and A1 is left connected to GND, the address is 0x28 + 0 + 1 = 0x29
  • If only A1 is tied to Vcc, the address is 0x28 + 2 + 0 = 0x2A (A is 10 in hexadecimal)
  • If both A0 and A1 are connected to Vcc, the address is 0x28 + 2 + 1 = 0x2B (B is 11 in hexadecimal)

This guide was first published on Jul 07, 2020. It was last updated on Jul 07, 2020.

This page (Pinouts) was last updated on Oct 07, 2021.

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