Build Your Perfect Macropad with the Ocreeb MK2 Modular System

We love macropads because they enhance productivity and they’re great projects for makers. On the productivity side, macropads can boost almost any workflow by providing quick and easy access to shortcuts and macros. The optimal layout and functionality depend on the specific workflow, which is why makers love to build macropads. If you want to make a macropad, but don’t know where to start, you should check out Salim Benbouziyane’s fantastic Ocreeb MK2 modular system.

Ocreeb MK2 is a “modular macro keyboard system” consisting of a central base unit, which contains a handful of programmable keys, and several different add-on modules to expand the capability. One module, for example, has two analog sliders that would be perfect for left and right audio channel faders. Another has a combination lock dial, which would provide a fun way set volume, to enter a password, or to “type” any other arbitrary sequence of numbers.

This system has a sensible grid layout and each module can occupy either a full square of that grid or a half-square. The base module uses a Seeed Studio XIAO RP2040 microcontroller development board and communicates with the connected PC via USB. Each add-on module contains a more basic ATtiny microcontroller to handle that module’s own functions, such as detecting key presses and setting LEDs.

Benbouziyane had to incorporate a communication protocol and a physical connector system for this modular plan to work. For communication between modules, he took advantage of Adafruit’s seesawPeripheral library based on the I2C protocol. That allows for expansion and for hardware interrupts. Benbouziyane wanted magnetic connectors for the modules, but the products on the market were pricey and so he made his own. Those use custom PCBs, pogo pins, and magnets in 3D-printed shrouds to transfer power and data between modules.

Each module also has its own custom PCB tailored to its function, as well as a custom 3D-printed enclosure and whatever else it needs (like key caps and knobs). To make those look like real consumer products, Benbouziyane utilized resin 3D printing.

Unfortunately, Benbouziyane still has some kinks to work out before Ocreeb MK2 is ready for the masses. There are issues with the interrupt system that become noticeable when there are several modules present. But Benbouziyane should be able to fix those problems in code, so the hardware will likely remain unchanged. If you’re the brave sort, you can follow Benbouziyane’s tutorial to build your own Ocreeb MK2 right now and then update the code later once he addresses the interrupt problem.