This page serves as documentation for the Fiddle.

The Fiddle turns an ioNode into a generic gadget platform.

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 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 (not counting the reset button)

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


WiFi is provided through the ESP8266 module from Espressif.

A library is provided to control the module: esp8266.

A tutorial is also available: Using an ESP8266 WiFi Module.


A MicroSD slot is included with the Fiddle. We provide a library for (micro-)SD cards: sdcard.

Another library is also provided to access FAT filesystems on such cards: fatfs.


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.