TEC.IST's Tiny Keyboard Sits in the Same Footprint as the Raspberry Pi Pico Which Drives It

Designed to take up as little room as possible, you'll need a steady hand if you want to type on this CircuitPython-powered keyboard.

Pseudonymous maker "TEC.IST" has built an ultra-compact yet functional keyboard, designed to be powered by a Raspberry Pi Pico microcontroller board — and taking up the same compact footprint.

"[This is] a very small keyboard, around the size of three pennies in a row," TEC.IST explains of his creation. There are BlackBerry keyboard-to-USB kits out there, though they require adapters and don't give you the full range of keys you might use with a PC. There are small(-ish) key matrix decoder keyboards out there as well, though the tactile switches tend to be larger and spaced further apart.

"What I settled on was a 59-key keyboard in the footprint of the Raspberry Pi Pico, with the microcontroller handling the key matrix decoding and USB interface."

This tiny yet fully-functional keyboard takes up no more room than a Raspberry Pi Pico. (📹: TEC.IST)

The tiny circuit board, which sits in the same footprint as the RP2040-based Raspberry Pi Pico, nevertheless manages to pack in a staggered QWERTY layout with dedicated number row, various modifier keys, and even a four-way directional arrow section. There are a few keys that have been sacrificed to save space, though, including Caps Lock and the function keys.

"To fit it all in I found a very small tactile switch, the B3U-1000P, measuring just 3×2.5×1.6mm (around 0.12×0.1×0.06")," TEC.IST explains. "Making key matrix connections by hand in such a tight space would be miserable, so a PCB was the way to go."

The resulting custom PCB plays host to a Raspberry Pi Pico surface-mounted to the rear, running CircuitPython and presenting itself as a USB Human Interface Device (HID). The resulting keyboard is functional, though lacks the diodes to prevent confusion if multiple non-modifier keys are pressed at once - and needs fine motor control to operate.

Full details, along with the source code and hardware design files, are available on TEC.IST's Hackaday.io project page.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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