Introducing Rubyduino, a Ruby to Arduino UNO compiler based on Matz's Spinel!

Source: Dev.to

Overview

Rubyduino (GitHub) compiles Ruby sketches for Arduino boards and uploads the generated firmware. Under the hood it uses Spinel, Matz’s Ruby AOT compiler, vendored at a pinned revision.

How it works?

Rubyduino adds a small Arduino runtime on top of the C code generated by Spinel. Functions such as digital_write, delay_ms, analog_read, serial_print, and pulse_in are mapped to tiny AVR C functions that interact directly with the Arduino UNO hardware registers.

The normal AVR toolchain then takes over:

1. Ruby sketch → Spinel turns it into C
2. Rubyduino adds the Arduino UNO runtime
3. avr-gcc compiles the C into firmware
4. avrdude uploads the firmware to the board

The Arduino is not interpreting Ruby; it runs compiled AVR machine code that originated as Ruby. No Firmata or RAD is involved—this is a brand‑new approach.

Tutorial

gem install rubyduino
touch blink.rb

# blink.rb
pin_mode(ArduinoUNO::LED_BUILTIN, ArduinoUNO::OUTPUT)

loop do
  digital_write(ArduinoUNO::LED_BUILTIN, ArduinoUNO::HIGH)
  delay_ms(100)
  digital_write(ArduinoUNO::LED_BUILTIN, ArduinoUNO::LOW)
  delay_ms(100)
end

rubyduino blink.rb

Result: