Keyboard Builders' Digest / Tips & Tricks
Sea-Picro
Josh Johnson released the Sea-Picro, a Pro Micro alternative with RP2040 and some neat features.
Published December 1, 2022
The Sea-Picro is a RP2040 based development board in the classic Pro Micro form factor. It's designed to be a drop in replacement for keyboards wanting an upgrade from ATmega32u4 based Pro Micros. (Thanks for the tip bgkendall!)
It comes in two variants: EXT and RST.
- EXT – featuring an Elite-C pinout, with dedicated 5V RGB LED pin, but without a reset button.
- RST – featuring a Pro Micro pinout, with onboard RGB LED and reset button.
Features
- Compatible with most Pro Micro based keyboards
- RP2040 microcontroller, with dual M0+ processors at up to 133MHz
- Mid-mount USB-C connector, which is low profile and can't be ripped off easily
- IO pinout identical to the Sparkfun RP2040 Pro Micro (RST) or Elite-C (EXT), adding an additional 5 IO for larger keyboards
- Single button reset
- ROM bootloader which prevents board from being bricked
- EXT version has a 5V level shifter and extra pin to drive strings of WS2812 LEDs.
- RST version has a WS2812 LED for use with CircuitPython or as a status indicator on the RST version.
- Onboard power LED.
One Button Reset
To makes life easier for keyboards that install the microcontroller upside down, or have limited access to the reset buttons, the Sea-Micro implements a one button reset with the associated circuitry:
One of the tricky things with the RP2040 is that unlike the pro micro, to update the firmware you need to use two buttons in sequence to put it into the bootloader – Josh.
To get around this, the Sea-Picro's circuit will reset the board when tapped for less than 500ms, but will jump into the bootloader when held for more than 1 second.
Availability
The Sea-Picro can be purchased from:
Sea-Micro
FYI, Josh released another controller earlier: the Sea-Micro is a Pro Micro alternative with USB C connector.
Resources
Published on Thu 1st Dec 2022. Featured in KBD #105.
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