denko

Program real-life electronics in Ruby. LEDs, buttons, sensors (and more) work just like any Ruby object:

led.blink 0.5

lcd.print "Hello World!"

reading = sensor.read

button.down do
  puts "Button pressed!"
end

There are currently two ways to use denko. Both have the same user-friendly API, but the hardware can be very different. Here's a summary of each:

• Flash a microcontroller with the denko C firmware, so it can be "remote controlled"
• Run a Ruby program on a "real" computer with the microcontroller connected
• The microcontroller appears as an instance of Denko::Board
• Calling its methods will send/receive message to manipulate the real microcontroller
• The microcontroller does only the bare minimum to send and receive signals
• Everything from peripheral drivers and up happens in Ruby, on the computer

• Install denko-piboard on your SBC
• Use it in a Ruby program, running on the SBC
• The SBC's GPIO header becomes a Denko::PiBoard instance, compatible with Denko::Board
• Everything runs self-contained on the SBC

Notes:

• Peripheral classes are implemented only in this gem, but work with both types of board, and both gems.
• That makes the examples folder of this gem (mostly) relevant to both.
• If using denko-piboard, ignore the hardware and installation sections here.

Microcontroller & Peripheral Support List

Note: On Windows you can follow the Mac/Linux instructions in WSL, but it isn't recommended. Serial (COM port) forwarding isn't working on WSL2, which means you can't communicate with the board. There are workarounds, and it might work on WSL1, but the RubyInstaller for Windows and Arduino IDE are recommended instead. A Linux virtual machine with USB passthrough works too.

gem install denko

Get the Arduino IDE here for a graphical interface (recommended for Windows), or use the command line interface from here, or Homebrew.

CLI Installation with Homebrew on Mac or Linux:

brew update
brew install arduino-cli

Denko uses Arduino cores, which support different microcontrollers, and a few libraries. Install only the ones for your microcontroller, or install everything. There are no conflcits. Instructions:

• Install Dependencies in IDE
• Install Dependencies in CLI

The denko command is included with the gem. It will make the Arduino sketch folder for you, and configure it.

Example for ESP32 target on both serial and Wi-Fi:

denko sketch serial --target esp32
denko sketch wifi --target esp32 --ssid YOUR_SSID --password YOUR_PASSWORD

# For more options
denko targets

Note: Boards flashed with a Wi-Fi or Ethernet sketch will listen for a TCP connection, but fall back to Serial when there is none active.

• Connect the board to your computer with a USB cable.
• Open the .ino file inside your sketch folder with the IDE.
• Open the dropdown menu at the top of the IDE window, and select your board.
• Press the Upload ➡️ button. This will compile the sketch, and flash it to the board.

Troubleshooting:

• If your serial port is in the list, but the board is wrong, select the serial port anyway, then you can manually select a board.
• If your board doesn't show up at all, make sure it is connected properly. Try disconnecting and reconnecting, use a different USB port or cable, or press the reset button after plugging it in.
• Some boards can get into a state where you have to hold their "boot" button while cycling power (reconnect or reset) for them to enter firmware update mode. Eg. Raspberry Pi Pico, ESP32-S2/S3.

• The path output by denko sketch earlier is your sketch folder. Keep it handy.
• Connect the board to your computer with a USB cable.
• Check if the CLI recognizes it:

arduino-cli board list

• Using the Port and FQBN (Fully Qualified Board Name) shown, compile and upload the sketch:

arduino-cli compile -b YOUR_FQBN YOUR_SKETCH_FOLDER
arduino-cli upload -v -p YOUR_PORT -b YOUR_FQBN YOUR_SKETCH_FOLDER

Troubleshooting:

• Follow the same steps as the IDE method above. List all FQBNs using:

arduino-cli board listall

Most boards have a regular LED on-board. Test with the blink example. If you have an on-board WS2812 LED (Neopixel), use the WS2812 blink example instead. If it starts blinking, you're ready for Ruby!

• Here you will find a beginner-friendly tutorial, that goes through the basics, using commented examples and diagrams. Read the comments and try modifying the code. You will need the following:

  • 1 compatible microcontroller (see supported hardware)
  • 1 button or momentary switch
  • 1 potentiometer (any value)
  • 1 external RGB LED (4 legs common cathode, not a Neopixel or individually addressable)
  • 1 external LED (any color, or use one color from the RGB LED)
  • Current limiting resistors for LEDs
  • Breadboard
  • Jumper wires

  Tip: Kits are a good way to get started. They include even more, and get you well beyond the tutorial.

• The examples folder contains at least one example per peripheral, demonstrating its interface.
• Each example should incldue a wiring diagram alongside its code (still incomplete).