Welcome to KeyChainino Blog!

KeyChainino is the first KeyChain game programmable with Arduino!

Hi, I’m Alessandro Matera the creator of KeyChainino.

If you are looking for portable vintage game to put in your  keychain,
to use when you’re on the subway, on the bus, or simply when you are bored and you don’t know how to spend your time, KeyChainino is for you!

Few months ago I was waiting for the bus and i realised that I was playing with my keys. So I had the idea to make something to play with in boring moments.

Something simple. Just for relaxing. A tiny device to play with, but a non-standard device.

A device made with Arduino where anyone can make it’s own game.

Without LCDs, just with LEDs!

With this idea, I’ve worked to a tiny device powered by the Atmel Attiny84 that controls a 6×5 Matrix LEDs.

The Attiny84 doesn’t have so many pins to drive all the 30 LEDs, so I’ve used Charlieplaxing to drive it. But don’t worry about it! I’ve created a simply function to drive the LEDs just like a simple and common LED matrix!

In this way I’ve have created my first game: a simple arkanoid-like, where a ball just bouncing on the screen and you need to move the paddle – with the two buttons – to prevents the ball from falling from the playing field.

Do you want to create your own game?

Just do it!

Check-out the Arduino Sketch of my game here and try to edit to make your personal, original, vintage and cool game with KeyChainino!

Follow this guide to upload the sketch.

See what Adafruit, Atmel, Geeky Gadgets and others say about KeyChainino!

P.S. If your game is really cool, send to me and I will publish it with your credits!


From the Blog:

    How to program KeyChainino v2 USB

    Follows these steps to program KeyChainino with an USB DATA cable.

    Be sure to use a micro USB data cable because many USB cable are for recharging only and you cannot use it.

    Use a standard CR2032 coin cell battery.

    1) Download and install Arduino IDE

    • If you haven’t already, download the Arduino software, Install the Arduino software, following the instructions for Windows, Mac OS X or Linux

    2) Download the Arkanoid game for KeyChainino V2 USB

    • Download the sketch here and open itscreen-shot-2017-04-29-at-13-09-31

    3) Connect KeyChainino V2 to the Computer

    • Like I said before, you must use a MICRO USB DATA CABLE
    • Connect the USB cable to the KeyChainino V2 and the PC's USB port. It's NOT necessary to remove the KeyChainino's battery because it has an onboard circuit that prevents the charging of the battery.


    • If you're using Mac OS or OS X you don't have to install drivers. Otherwise if you use a Windows OS, drivers should be automatically installed plugging with an USB cable the board to your PC, but with some version of the Windows operative system (like Windows 7, Vista and 10) it can happen that your board won't be recognized and you will get the message Unknown USB device. It is so necessary to manually install them following the guide Manually install Drivers on Windows.

    4) Select the right Board and Port on Arduino IDE

    • On the Arduino IDE, go to Tools -> Board, and select LilyPad Arduino USBscreen-shot-2017-04-29-at-13-42-31
    • Next, with KeyChainino V2 connected via USB, press and hold the A and B KeyChainino's buttons. When the KeyChainino smile face comes up, keep hold for another 2 seconds. Release the two buttons and all KeyChainino LEDs will blink. Now you are in programming mode. In this mode you can see the USB - Serial communication in the Arduino IDE
    • On the Arduino IDE go to Tools -> Port and select the right port where KeyChainino is connected. It should be indicated with the name "LilyPad Arduino USB", but it depends on your operating system.screen-shot-2017-04-29-at-13-49-56

    5) Upload the Sketch

    • Just press the Arduino IDE upload Button


    • Now you should see "Done uploading" at the bottom of the Arduino IDEscreen-shot-2017-04-29-at-13-58-40
    • Now you can play with the Arkanoid Game!

    Fixing problems:

    If your KeyChainino V2 USB won't boot up and/or your Arduino IDE doesn't show the Serial Port, try these steps in order:

    • Check if the micro USB Cable is OK and if it is a DATA CABLE, if not, change the cable
    • If you made some changes on the original Sketch and KeyChainino won't start and/or you're not able to upload a new sketch anymore:
      • open the Arkanoid ORIGINAL sketch (Download here)
      • connect KeyChainino to the PC with a USB DATA cable
      • then double press the RESET button on the KeyChainino Board


      • Rapidly select the Port of KeyChainino in the Arduino IDE
      • Upload the sketch


    Click here for the full post

    How to program KeyChainino v1 via ISP

    Follows these steps to program KeyChainino with Arduino or an ISP Programmer:

    Click here for the full post

    Some changes on the basic sketch

    I have had a problem making a simple sketch to KeyChainino. The problem was that if I put the code below on the basic sketch to just blinking one LED of the matrix, the LED only turns OFF and never goes ON.

    void loop() {
      matrixState[0][0] = 1;
      matrixState[0][0] = 0;
    Click here for the full post