General • Pico2 RP2350: can't use GPIO26/27 as uart

Hi, I'm trying to use the GPIO pins 26 and 27 as TX and RX for UART1, which according to the RP2350 Datasheet is possible (Function 11 for those pins).
But somehow it doesn't work.
What I tried:

1.
I cloned the official raspberrypi/debugprobe repo, change the PROBE_UART_TX/RX defines (https://github.com/raspberrypi/debugpro ... .h#L43-L44) to 26/27, compiled for Pico2.
Interesting observation: the unmodified debugprobe software works (TX/RX = 4/5). When having that flashed, GPIO26 is low (as expected, because unused/unconfigured). After flashing my modified version, GPIO26 is high (as expected, because the TX idle state is high, so SOMETHING seems to be correct). But GPIO26 is never going low, even when it should be transmitting. I tested this with a logic analyzer, so no baudrate mismatch is involved here.
Receiving did not work, either.

2.
I cloned https://github.com/Menci/pico-uart-bridge, changed the UART1 TX/RX defines (https://github.com/Menci/pico-uart-brid ... .c#L27-L28) to 26/27, updated the pico-sdk,compiled for Pico2.
In this experiment, GPIO26 didn't even go high after my code change.

What am I missing?

Statistics: Posted by csierra — Mon Apr 14, 2025 8:28 pm — Replies 0 — Views 38

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