I2C Encoder Mini

What is it?

The I2C Encoder Mini is a small board where you can use a rotary encoder with a I2C bus. This can be useful in case you have few GPIO because with 3 pin you can control up to 127 devices. The I2C Encoder Mini will count and store every movement of the encoder, so no need to check the rotary encoder in real-time, the I2C Encoder Mini will do it!

This is a mini version of I2C Encoder V2.1.


  • I2C bus working up to 400kHz
  • Possibility to customize the I2C address with the I2C bus
  • It supports the standard rotary encoder
  • Open-drain Interrupt output pin, so no need to continuously poll the devices
  • 5 pin header 2.54mm pitch on the left and right side, also the JST-XH fit
  • 127byte of internal EEPROM
  • Voltage range is 3.3V to 5V
  • Maximum A/B signal frequency: 100Hz (Tested)
  • Dimension of 23x19mm or 0.9×0.74in
  • Open source project


This new version is powered by the ATtiny 402. It have a similar feature of the big brother, but it support only the mechanical encoder (no RGB) and there is no GP pins.

The I2C Encoder Mini have also pre-soldered the pull-up resistor on the I2C bus. The can be enabled by soldering a jumper.

Reading the encoder is a very easy task.

There are 4 32bit signed int registers:

  • CVAL: Current value of the Encoder. This value changes every time the encoder rotates.
  • CMAX: Maximum value that CVAL can reach
  • CMIN: Minimum value that CVAL can reach
  • ISTEP: How much the CVAL has to increment at each and every encoder step.



Shipping is done every Monday morning, please place the order before!

Package includes:

1 I2C Encoder Mini board fully assembled, programmed and tested (without encoders, connectors)

I2C Encoder Mini

However, there are some accessory that you can add into your order according to your preference. The accessories are not soldered, you have solder by your self.


There are 4 types of standard encoders. All have 20 pulses for rotations and the push button:

  • EC11 with handle 20mm long and 6mm diameter.
  • EC11 with handle 15mm long and 6mm diameter.
  • Bourns PEC11L-4115F-S0020 with handle 15mm long and 6mm diameter.
  • Bourns PEC11L-4120F-S0020 with handle 20mm long and 6mm diameter.
  • Bourns PEC11L-4020F-S0020 no dent with handle 20mm long and 6mm diameter.

Different types of available encoders


There are also 2 type of connector:

  • Male and female 5 pin header
  • JST connector with 30cm wire

Example of male and female 5 pin header

Example of male and femele 5 pin header

Comparison between the I2C Encoder V2.1 and I2C Encoder Mini


Similar project:

I2C Encoder V2.1

I2C NavKey

You can purchase these items also in our Tindie and eBay stores: