Cherry MX keypad


Dan Watson documented on his blog an open source Arduino-compatible Cherry MX keypad he designed using the ATmega32U4 microcontroller:

The board that I designed includes four Cherry MX keys. I used MX Blues, but it is also compatible with other types such as Brown and Red. It’s simply a matter of soldering on the ones you want. The keys are backlit by 3mm LEDs that sit in recesses in the sides of the keys. They are controlled via PWM to allow changing the brightness. The microcontroller running the show is an Atmel ATmega32U4. This is the same microcontroller used on the Arduino Leonardo. In fact, this board looks like a Leonardo to the Arduino IDE for programming. There is an ISP port for burning the bootloader with a programmer (Atmel ICE, USBtinyISP, etc), but you only need to do that once. Afterwards simply connect the board to your computer using the Micro USB connector for programming and normal usage.

More detailsĀ atĀ The Sync Channel blog. Project files are available on Github.

Check out the video after the break.


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  1. I’ve been so used to FET load switching that I was pleasantly surprised by the LED backlights load switch, an MMBT222A (NPN) used as an emitter follower. And no resistor at the base pin… I guess he’s just letting the I/O pin drive saturate to ~20mA. But with so many I/O lines, why didn’t he just use a few I/O lines to individually control the LEDs?

  2. I started looking at keyboards, for a calculator… it’s a [potential] minefield.
    The Cherry MX series are great mechanical switches, and readily available. Unfortunately, like a standard keyboard, they tend to require a spacing of 19 mm and are relatively tall.
    The ML series are smaller (12mm spacing from memory) and lower profile “chicklet” style. However it’s harder to find custom keycaps, and any text you wanted to put on the FRONT of the key gets moved to the top, making a potentially messy design.

    If you want pretty color LEDS things get worse. Just getting an end product that works becomes an achievement.

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