Default uart fixups #3185

2026-09-07T04:35:12-05:00

will-v-pi commented

2026-09-07 04:35:12 -05:00

(Migrated from github.com)

Add UART_CLK_DEST_PERI() and UART_CLK_DEST_SYS() macros to use in low power

Document the pairing between stdio/stdout/stdin init/deinit functions

Fix and simplify the PICO_DEFAULT_UART_TX_PIN/RX_PIN checks

Fixes #3172 and #3173

Add `UART_CLK_DEST_PERI()` and `UART_CLK_DEST_SYS()` macros to use in low power Document the pairing between `stdio`/`stdout`/`stdin` `init`/`deinit` functions Fix and simplify the `PICO_DEFAULT_UART_TX_PIN`/`RX_PIN` checks Fixes #3172 and #3173

kilograham (Migrated from github.com) reviewed

2026-09-07 04:35:12 -05:00

lurch (Migrated from github.com) reviewed

2026-09-08 06:07:53 -05:00

src/rp2_common/hardware_uart/include/hardware/uart.h

					
				@ -188,1 +210,4 @@

				#define UART_CLK_DEST_SYS(uart) (uart_get_index(uart) ? CLK_DEST_SYS_UART1 : CLK_DEST_SYS_UART0)

				#endif

				/**

 * \brief Returns \ref clock_dest_num_t of the clk_sys dest for the given UART instance

?

```suggestion * \brief Returns \ref clock_dest_num_t of the clk_sys dest for the given UART instance ``` ?

lurch (Migrated from github.com) reviewed

2026-09-08 06:10:09 -05:00

src/rp2_common/hardware_uart/include/hardware/uart.h

					
				@ -188,0 +198,4 @@

				#define UART_CLK_DEST_PERI(uart) (uart_get_index(uart) ? CLK_DEST_PERI_UART1 : CLK_DEST_PERI_UART0)

				#endif

				/**

I don't know much about how the clocks work, but is "the clk_peri dest for the given UART instance" something that needs a better explanation? 🤷
(Does "dest" mean "destination", or something else?)

I don't know much about how the clocks work, but is "the clk_peri dest for the given UART instance" something that needs a better explanation? :shrug: (Does "dest" mean "destination", or something else?)

lurch (Migrated from github.com) reviewed

2026-09-08 06:12:54 -05:00

src/rp2_common/pico_stdio_uart/include/pico/stdio_uart.h

What does "disables for output" / "disables for input" mean? 😉

What does "disables for output" / "disables for input" mean? :wink:

lurch (Migrated from github.com) reviewed

2026-09-08 06:14:08 -05:00

src/rp2_common/pico_stdio_uart/include/pico/stdio_uart.h

 * This method disables PICO_DEFAULT_UART_RX_PIN for UART input (if defined), and leaves the pad isolated

```suggestion * This method disables PICO_DEFAULT_UART_RX_PIN for UART input (if defined), and leaves the pad isolated ```

will-v-pi (Migrated from github.com) reviewed

2026-09-08 06:17:03 -05:00

src/rp2_common/pico_stdio_uart/include/pico/stdio_uart.h

I’m not sure - that’s pre-existing wording, I was just adding the comma. The only thing it actually does to the pins is isolate them on RP2350.

will-v-pi (Migrated from github.com) reviewed

2026-09-08 06:19:41 -05:00

src/rp2_common/hardware_uart/include/hardware/uart.h

					
				@ -188,0 +198,4 @@

				#define UART_CLK_DEST_PERI(uart) (uart_get_index(uart) ? CLK_DEST_PERI_UART1 : CLK_DEST_PERI_UART0)

				#endif

				/**

It means destination, but I used dest to match the abbreviation used in the enum clock_dest_num_t

It means destination, but I used dest to match the abbreviation used in the enum `clock_dest_num_t`

lurch (Migrated from github.com) reviewed

2026-09-08 06:22:22 -05:00

src/rp2_common/pico_stdio_uart/stdio_uart.c

					
				@ -25,3 +26,3 @@

				#ifdef PICO_DEFAULT_UART_TX_PIN

				#if (PICO_DEFAULT_UART_TX_PIN & 0x1) || (PICO_RP2040 && (PICO_DEFAULT_UART_TX_PIN & 0x2))

				#if (PICO_DEFAULT_UART_TX_PIN % 2) || (PICO_RP2040 && (PICO_DEFAULT_UART_TX_PIN % 4))

				#error "Specified PICO_DEFAULT_UART_TX_PIN does not support UART TX"

Is it also worth checking that PICO_DEFAULT_UART_TX_PIN is below a particular value? (e.g. #define PICO_DEFAULT_UART_TX_PIN 100 obviously wouldn't work 🙂 )
I guess it depends how much needs to be checked in the code, and how much can just be assumed to have been already checked by https://github.com/raspberrypi/pico-sdk/blob/develop/tools/check_board_header.py ?

Is it also worth checking that PICO_DEFAULT_UART_TX_PIN is below a particular value? (e.g. `#define PICO_DEFAULT_UART_TX_PIN 100` obviously wouldn't work :slightly_smiling_face: ) I guess it depends how much needs to be checked in the code, and how much can just be assumed to have been already checked by https://github.com/raspberrypi/pico-sdk/blob/develop/tools/check_board_header.py ?

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