Atmel 32u4 boards wiring

using dupont cables and connectors

To connect our Arduino Leonardo, Micro, Teensy 2.0 or ProMicro board, we are going to need Dupont type cable extensions, male and/or female.

It’s also useful to use a 20 pins strip to plug to the C-64 keyboard connector, you just have to remove two non-used pins. In the other end, you are going to need female or male Dupont connector, according of your board.

Here you have an example of male pins for the Arduino Leonardo board.


Arduino Leonardo

This is the pinout to connect our Arduino Leonardo to the keyboard, and RGB (or normal) LED.

If you prefer to use the original red LED of your C64, remember to insert a ~330 Ohms resistor!!!

Arduino Micro

The Arduino Micro board has to be connected this way. Warning: The board is facing down in the schematics. Read below about pins orientation.

Pins orientation.

Fortunately,  this boards usually comes with the soldering over the green side, so you plug cables to the white side.

Unfortunately, this board also comes with the six inner pins soldered to the opposite side than the outer pins. If that is the case, you need to remove or trim the six inner pins because the board won’t fit in it’s housing, it’s designed for the white side facing up.

If you buy a board without soldered pins, remember to solder them to the green side, in order to be plugged over the white side of the board.

Teensy 2.0

The Teensy 2.0 is connected this way. You can also replace the RGB LED for a monochromatic one, just remember the ~300 Ohms.

Warning: This board hasn’t been tested yet due to not having one. It has been done using the same code than other 32u4 boards changing only pins input assignment so it should work. In case it doesn’t please let me know.


For the popular ProMicro, follow this schematic.

Unfortunately, the ProMicro board has only 18 inputs/outputs so there is no free pins for controlling a LED.

However it has two built in LEDs, so Modes of Compatibility will be shown using them (those who has experience soldering sourface-mount components, can solder wires to a RGB LED).

The (optional) LED in the diagram is a Power LED. It will show if the board is powered or not (like the LED of the C-64 case).

Optional connection for original Atari/commodore Joysticks

As explained before, the Atmel 32u4 board does not have enough pins to allocate the two Joysticks separately, so some «Y» connections in parallel are needed, as exlained here.

Below there’s the schematics and an example wired connector with female pins.  

Important Note: BMC64 Emulator allows direct connection of Joystick to Raspberry Pi’s GPIO, so if you plan to use ONLY that emulator for joysticks, you can wire them to the Pi.