Japi Base v0.4 — PS/2 keyboard noise immunity

What's new

More robust PS/2 keyboard input on noisy setups. The PS/2 PIO state machine ran at full system clock (260 MHz), making it sensitive enough that nanosecond glitches on the clock line — common with long jumper wires, breadboards, or a USB-to-PS/2 bridge — were misread as falling edges and corrupted keystrokes. The SM clock is now divided down to ~160 kHz, which low-pass filters those glitches while still oversampling the 16.7 kHz max PS/2 clock about 10x. Clean setups are unaffected; noisy ones become reliable.

Diagnosed by a Raspberry Pi forum user running a USB-to-PS/2 bridge — thanks!

Install

Hold BOOTSEL while plugging in the Pico 2, then copy japi_base_v0.4.uf2 onto the RP2350 drive.

Full changelog: v0.3...v0.4