stmhal: Document physical pins for SPI, I2C, UART busses.

1 files changed, 8 insertions, 0 deletions

diff --git a/stmhal/uart.c b/stmhal/uart.c
index 8f263dbd8..5bbd9f299 100644
--- a/stmhal/uart.c
+++ b/stmhal/uart.c
@@ -311,6 +311,14 @@ STATIC mp_obj_t pyb_uart_init_helper(pyb_uart_obj_t *self, uint n_args, const mp
 /// initialised (it has the settings from the last initialisation of
 /// the bus, if any).  If extra arguments are given, the bus is initialised.
 /// See `init` for parameters of initialisation.
+///
+/// The physical pins of the UART busses are:
+///
+///   - `UART(4)` is on `XA`: `(TX, RX) = (X1, X2) = (PA0, PA1)`
+///   - `UART(1)` is on `XB`: `(TX, RX) = (X9, X10) = (PB6, PB7)`
+///   - `UART(6)` is on `YA`: `(TX, RX) = (Y1, Y2) = (PC6, PC7)`
+///   - `UART(3)` is on `YB`: `(TX, RX) = (Y9, Y10) = (PB10, PB11)`
+///   - `UART(2)` is on: `(TX, RX) = (X3, X4) = (PA2, PA3)`
 STATIC mp_obj_t pyb_uart_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
     // check arguments
     mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);