From 8b1b3b7ff314e0d27a0a878c9e422b5bba5ed59e Mon Sep 17 00:00:00 2001
From: Erick Ahmed <engineering@erickahmed.com>
Date: Tue, 16 Jun 2026 19:49:13 +0200
Subject: [PATCH] Implement safe UART semaphore release inside ISR

- It uses safe way to release semaphore
- Yields in case task interrupted was of lower priority: UART has
  minimal latency
---
 Core/Src/cansend.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/Core/Src/cansend.c b/Core/Src/cansend.c
index 55ee5c2..354e43c 100644
--- a/Core/Src/cansend.c
+++ b/Core/Src/cansend.c
@@ -20,5 +20,17 @@
 #include "cmsis_os.h"
 /* USER CODE END Includes */
 
-void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart);
-void vUARTLogger(void *argument);
+void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
+{
+  if (huart->Instance == USART1)
+  {
+    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
+    osSemaphoreReleaseFromISR(xUartDmaSem, &xHigherPriorityTaskWoken);
+    portYIELD_FROM_ISR(xHigherPriorityTaskWoken);
+  }
+}
+
+void vUARTLogger(void *argument)
+{
+
+}