This page serves as documentation for the Fiddle.

The Fiddle is a tiny UI module featuring the same footprint as the ioNode.

This means the module can be easily added to any project based on the ioNode, to provide a simple user interface.
It can also be attached directly to an ioNode.

Hardware Interface

Footprint is compatible with the ioNode - it is made to be attached as a "backpack" module to an ioNode or a project using an ioNode.

The Fiddle does not use any pins other than the I2C bus, meaning that it can be added to any ioNode-based project without modification, provided the I2C bus is available.


The display is a 128x32 OLED using the very common SSD1306 driver.
These displays communicate via I2C.

A library is provided to control the display: ssd1306.

A tutorial is also available: Using an I2C OLED display


The Fiddle offers 7 inputs:
  • 5-way tactile switch (mini-joystick)
  • 2 buttons

All inputs are wired to an MCP23008 I2C I/O expander from Microchip.
The address bits are wired as 0x04.


The Dooba SDK includes a library to facilitate development using the Fiddle: fiddle.

The wiki also includes a tutorial explaining how to use it: Using the Fiddle.