Merge pull request #5834 from adafruit/rpi-uart-claim-later

raspberrypi: Claim UART after checking pins

Author: tannewt

ports/raspberrypi/common-hal/busio/UART.c

@@ -120,14 +120,14 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
 
     if (uart_status[uart_id] != STATUS_FREE) {
         mp_raise_RuntimeError(translate("All UART peripherals are in use"));
-    } else {
-        uart_status[uart_id] = STATUS_BUSY;
     }
-
+    // These may raise exceptions if pins are already in use.
     self->tx_pin = pin_init(uart_id, tx, 0);
     self->rx_pin = pin_init(uart_id, rx, 1);
     self->cts_pin = pin_init(uart_id, cts, 2);
     self->rts_pin = pin_init(uart_id, rts, 3);
+    uart_status[uart_id] = STATUS_BUSY;
+
 
     self->uart = UART_INST(uart_id);
     self->uart_id = uart_id;