The replacement keyboard controller!

The originial Pro Micro Arduino clone based on the Atmel Atmega32u4 MCU has been the gold standard for DIY based keyboard designs since about a decade or more. Unfortunately, with Covid came a shift in what was produced and in what quantities, And even though the Atmega32u4 is arguably the most used MCU for DIY purposes, it is getting old, and there are plenty of newer, more powerful replacements. Thus the price and availability of the Pro Micro controllers have continued to shift in the wrong direction since then.

Several high spec Pro Micro replacements exist on the market today, like the Frood, Elite Pi and Liatris, all at prices reflecting their various options and spec, and I very highly recommend building your keyboard with one of these. However, if you like me very often want a bargain build, or at the very least bang-for'buck pricing, a cheap clone might be the right choice.

Specification

RP2040 General Specification

• RP2040 MCU, Dual-core Arm Cortex M0+ processor, flexible clock running up to 133 MHz
• 264KB of SRAM (No on-board Flash memory)
• USB-C connector, (USB 1.1 device and host support)
• Low-power sleep and dormant modes
• Drag-and-drop programming using mass storage over USB
• 2 × SPI, 2 × I2C, 2 × UART, 4 × 12-bit ADC, 16 × controllable PWM channels
• Accurate clock and timer on-chip
• Temperature sensor
• Accelerated floating-point libraries on-chip
• 8 × Programmable I/O (PIO) state machines for custom peripheral support

RP2040 'Pro Micro' Specification

• 4MB of Flash memory (Also used to emulate EE_PROM memory)
• Conforms to the 'original' Pro Micro design and outline (USB port does not extend as USB type C Pro Micro).
• Pin compatible with Pro Micro and Elite C (5 Extra pins on bottom as Elite C).
• 5 additional IO available outside the original Pro Micro/Elite C footprint
• Low profile with 'mid-mount' USB type C connector and NO components on backside.
• BOOT pin available as through hole, accessible from the back (Very useful when mounted in a keyboard!).

What's included

As standard, these are delivered in a sealed ESD bag, with the pinheaders just like any Pro Micro clone.

I'm merely reselling these AS-IS to make it a one-stop-shop for building your keyboard.

Please note! You can likely find them cheaper on AliExpress or similar if you are willing to order from various sources, or order in bulk. I'm merely covering my expenses, shipping/taxes etc, with no measureable profit on these.

Building with these instead of an original ProMicro

When building an existing legacy design (like the Lotus 58) simply ignore the extra pins!

Instead fit the controller to the original ProMicro footprint, with the top two pins next to the USB port unconnected, and it just works as intended.

The extra pins can be used in new designs, but are never used in a legacy design that was designed for a ProMicro or EliteC.

How-to Flash an RP2040 based controller

For starters, forget the QMK Toolbox exist!!

It is not for you, even though the idea seems convenient.

Here is a guide to flashing:

Discord Help channel

Normal handling time is 3 - 5 working days, not including build items (Those usually take 1 - 2 weeks).

Shipping is done with insured/signed for parcels, where no such service is available the parcel is sent as insured parcel, but may not be fully traceable the entire transit. If no insured or traceable service is available, parcels will be sent as uninsured/untraceable at the buyers responsibility. All of which is clearly stated on checkout.

All packets are represented to courier services and customs at their true sale value, and all responsibility for import fees, taxes and tariffs lie with the buyer.

The SE/EU "Act on Distance Contracts and Off-Premises Contracts (SFS 2005:59)" allows returns of the items in undamaged (unsoldered!) condition within 14 days of receiving it. Return shipping on returned items are the responsibility of the buyer.