Microcontrollers are cool, but sometimes the user interface options they can deliver are disappointing. The platform in question may not have the horsepower required to drive a decent screen, and often a web interface is undesirable for security or complexity reasons. Sometimes you just need a good software interface between chip and computer. Firmata is a protocol that’s designed to do just that, and [nanoflite] has brought it to the Commodore 64.

It’s a fun project, which allows one to use the C64’s charming retro graphics to interface with an Arduino-based project. Connection is achieved at 2400bps over the user port, which is plenty fast for most UI applications. [nanoflite] demonstrates the interface with an Arduino Uno and a Grove shield. The C64 is able to display the state of the LED, relay and servo outputs, as well as read the Arduino’s button and potentiometer inputs.

It’s an excellent way to integrate a Commodore 64 into a microcontroller setup without reinventing the wheel. We think it would make an awesome vintage interface to a home automation system or similar build. If you’re interested, but you don’t have a C64 of your own to play with, never fear – you can just build a new one.

Retrocomputers are fun, but ultimately limited in capability compared to modern hardware. One popular pursuit to rectify this is the connection of early home computers to the Internet. To that end, [que] built the Retromodem for the Commodore 64.

The build starts with a case from an Intel 14.4 modem. A little fast for the Commodore 64 era, but anachronism is charming when done tastefully. Inside is an Arduino with an ethernet module to handle the heavy lifting of carrying packets to the outside world.  [que] took the time to wire up status LEDs for the proper vintage look, which really adds something to the project. They switch on and off to indicate the various settings on the modem – it’s great to see in the video below the break the “HS” LED light up when the baud rate is changed to a higher speed.

The project implements most of the Hayes command set, so you can interface with it over a serial terminal just like it’s 1983. [que] doesn’t go into too many details of how it’s all put together, but for the experienced code warrior it’s a project that could be whipped up in a weekend or two. For a more modern take, perhaps you’d like to hook your C64 up over Wifi instead?

There’s a lot of reasons you might want to emulate the keyboard on your Commodore 64. The ravages of time and dust may have put the original keyboard out of order, or perhaps you need to type in a long program and don’t fancy pecking away with the less-than-stellar feedback of the standard keys. [podstawek] has come up with the solution: a Commodore 64 keyboard emulator that works over serial.

It’s a simple concept, but one that works well. A Python script accepts incoming keypresses or pre-typed text, then converts them into a 6-bit binary code, which is sent to an Arduino over the serial connection. The Arduino uses the 6-bit code as addresses for an MT8808 crosspoint switch.

The MT8808 is essentially an 8×8 matrix of controllable switches, which acts as the perfect tool to interface with the C64’s 8×8 keyboard matrix. Hardware wise, this behaves as if someone were actually pressing the keys on the real keyboard. It’s just replacing the original key switches with an electronic version controlled by the Arduino.

[podstawek] already has the setup working on Mac, and it should work on Linux and Windows too. There’s a little more to do yet – modifying the script to allow complex macros and to enable keys to be held – so check out the Github if you want to poke around in the source. Overall it’s a tidy, useful hack to replace the stock keyboard.

The C64 remains a popular platform for hacking — it’s even had a Twitter client since 2009.