From a54bc47e1bac6101421d1dfde5fe542d59b3152a Mon Sep 17 00:00:00 2001
From: Steve Evans <SteveCEvans@users.noreply.github.com>
Date: Tue, 8 Aug 2023 06:49:51 +0100
Subject: [PATCH] Enable/disable the UART TX before changing the TX pin mode
 (#13017)

---
 src/main/drivers/stm32/serial_uart_hal.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/main/drivers/stm32/serial_uart_hal.c b/src/main/drivers/stm32/serial_uart_hal.c
index 136ececcb0..6913df56ec 100644
--- a/src/main/drivers/stm32/serial_uart_hal.c
+++ b/src/main/drivers/stm32/serial_uart_hal.c
@@ -251,6 +251,10 @@ bool checkUsartTxOutput(uartPort_t *s)
             // Enable USART TX output
             uart->txPinState = TX_PIN_ACTIVE;
             IOConfigGPIOAF(txIO, IOCFG_AF_PP, uart->tx.af);
+
+            // Enable the UART transmitter
+            SET_BIT(s->Handle.Instance->CR1, USART_CR1_TE);
+
             return true;
         } else {
             // TX line is pulled low so don't enable USART TX
@@ -268,6 +272,9 @@ void uartTxMonitor(uartPort_t *s)
     if (uart->txPinState == TX_PIN_ACTIVE) {
         IO_t txIO = IOGetByTag(uart->tx.pin);
 
+        // Disable the UART transmitter
+        CLEAR_BIT(s->Handle.Instance->CR1, USART_CR1_TE);
+
         // Switch TX to an input with pullup so it's state can be monitored
         uart->txPinState = TX_PIN_MONITOR;
         IOConfigGPIO(txIO, IOCFG_IPU);