From 4b2cd53f3b8ca72fbcfed6381f082817c4cd115a Mon Sep 17 00:00:00 2001
From: Erick Ahmed <engineering@erickahmed.com>
Date: Mon, 15 Jun 2026 13:46:31 +0200
Subject: [PATCH] Transition from timer based to task based LED signal

- Remove RTOS timers
- Create LED task
- Avoid polling, instead wait for semaphore
---
 Core/Inc/canlog.h |  1 -
 Core/Src/canlog.c | 54 +++++++++++++++++++++++------------------------
 Core/Src/main.c   | 38 ++++++++++++++++-----------------
 3 files changed, 45 insertions(+), 48 deletions(-)

diff --git a/Core/Inc/canlog.h b/Core/Inc/canlog.h
index d741aff..72ea736 100644
--- a/Core/Inc/canlog.h
+++ b/Core/Inc/canlog.h
@@ -45,7 +45,6 @@ typedef struct {
 typedef struct {
     LED_Config *led;
     osSemaphoreId_t semaphore;
-    osTimerId_t timer;
 } LEDContext;
 /* USER CODE END PTD */
 
diff --git a/Core/Src/canlog.c b/Core/Src/canlog.c
index 45b2935..739ee47 100644
--- a/Core/Src/canlog.c
+++ b/Core/Src/canlog.c
@@ -97,22 +97,13 @@ void HAL_CAN_RxFifo0MsgPendingCallback(CAN_HandleTypeDef *hcan)
   */
 void vCANLoggerListen(void *argument)
 {
-    /* CODE BEGIN */
-    CAN_HandleTypeDef *hcan = (CAN_HandleTypeDef*)argument;
-    osMessageQueueId_t queue;
-    CanMessage_t message;
+  /* CODE BEGIN */
+  LEDContext *context = (LEDContext*)argument;
 
-    queue = (hcan->Instance == CAN1) ? xCAN1RxQueue : xCAN2RxQueue;
-
-    for (;;)
-    {
-        if (osMessageQueueGet(queue, &message, NULL, osWaitForever) == osOK)
-        {
-            osSemaphoreRelease( (hcan->Instance == CAN1) ? xSemaphoreCAN1 : xSemaphoreCAN2 );
-            // TODO: use this semaphore
-        }
-
-    }
+  for (;;)
+  {
+    if (osSemaphoreAcquire(context->semaphore, 25U) == osOK) HAL_GPIO_WritePin(context->led->port, context->led->pin, GPIO_PIN_SET);
+    else HAL_GPIO_WritePin(context->led->port, context->led->pin, GPIO_PIN_RESET);
     /* CODE END */
 }
 /* END vCANLoggerListen */
@@ -125,19 +116,28 @@ void vCANLoggerListen(void *argument)
   */
 void vLEDHeartbeat(void *argument)
 {
-  /* CODE BEGIN */
-  LEDContext *context = (LEDContext*)argument;
+    /* CODE BEGIN */
+    LEDContext *context = (LEDContext*)argument;
 
-  if (osSemaphoreAcquire(context->semaphore, 0U) == osOK)
-  {
-      HAL_GPIO_WritePin(context->led->port, context->led->pin, GPIO_PIN_SET);
-      osTimerStart(context->timer, 25U);
-  }
-  else
-  {
-      HAL_GPIO_WritePin(context->led->port, context->led->pin, GPIO_PIN_RESET);
-  }
-  /* CODE END */
+    for (;;)
+    {
+        // BLOCK for UP TO 25ms.
+        // - Returns osOK instantly if CAN traffic arrives.
+        // - Returns osTimeout if 25ms pass with NO traffic.
+        if (osSemaphoreAcquire(context->semaphore, 25U) == osOK)
+        {
+            // Traffic detected! Turn ON LED.
+            // Loop immediately to wait for the next message.
+            HAL_GPIO_WritePin(context->led->port, context->led->pin, GPIO_PIN_SET);
+        }
+        else
+        {
+            // Timeout! No CAN traffic for 25ms. Turn OFF LED.
+            // Loop and block again.
+            HAL_GPIO_WritePin(context->led->port, context->led->pin, GPIO_PIN_RESET);
+        }
+    }
+    /* CODE END */
 }
 /* END vLEDHeartbeat */
 /* USER CODE END FunctionPrototypes */
diff --git a/Core/Src/main.c b/Core/Src/main.c
index ff7bb39..26287f1 100644
--- a/Core/Src/main.c
+++ b/Core/Src/main.c
@@ -55,9 +55,6 @@ LEDContext ledContextCAN2;
 osSemaphoreId_t xSemaphoreCAN1;
 osSemaphoreId_t xSemaphoreCAN2;
 
-osTimerId_t xHeartbeatTimerCAN1;
-osTimerId_t xHeartbeatTimerCAN2;
-
 osMessageQueueId_t xCAN1RxQueue;
 osMessageQueueId_t xCAN2RxQueue;
 /* USER CODE END PV */
@@ -126,12 +123,27 @@ int main(void)
     .stack_size = 128 * 4,
     .priority = (osPriority_t) osPriorityRealtime1,
   };
+
   osThreadId_t xCAN2rx;
   const osThreadAttr_t CAN2rxAttributes = {
     .name = "CAN2rx",
     .stack_size = 128 * 4,
     .priority = (osPriority_t) osPriorityRealtime,
   };
+
+  osThreadId_t xLEDHeartbeatCAN1;
+  const osThreadAttr_t LEDHeartbeatCAN1Attributes = {
+    .name = "LED_HB_CAN1",
+    .stack_size = 128 * 4,
+    .priority = (osPriority_t) osPriorityVeryLow1,
+  };
+
+  osThreadId_t xLEDHeartbeatCAN2;
+  const osThreadAttr_t LEDHeartbeatCAN2Attributes = {
+    .name = "LED_HB_CAN2",
+    .stack_size = 128 * 4,
+    .priority = (osPriority_t) osPriorityVeryLow,
+  };
   /* USER END RTOS_TASKS */
 
   /* USER CODE BEGIN RTOS_MUTEX */
@@ -151,21 +163,14 @@ int main(void)
   /* USER CODE END RTOS_SEMAPHORES */
 
   /* USER CODE BEGIN RTOS_TIMERS */
-  xHeartbeatTimerCAN1 = osTimerNew(vLEDHeartbeat, osTimerOnce, &ledContextCAN1, NULL);
-  xHeartbeatTimerCAN2 = osTimerNew(vLEDHeartbeat, osTimerOnce, &ledContextCAN2, NULL);
-
-  osTimerStart(xHeartbeatTimerCAN1, 25U);
-  osTimerStart(xHeartbeatTimerCAN2, 25U);
-
-  if (xHeartbeatTimerCAN1 == NULL || xHeartbeatTimerCAN2 == NULL) Error_Handler();
-
-  ledContextCAN1.timer = xHeartbeatTimerCAN1;
-  ledContextCAN2.timer = xHeartbeatTimerCAN2;
+  /* add timers, ... */
   /* USER CODE END RTOS_TIMERS */
 
   /* USER CODE BEGIN RTOS_QUEUES */
   xCAN1RxQueue = osMessageQueueNew(32, sizeof(CanMessage_t), NULL);
   xCAN2RxQueue = osMessageQueueNew(32, sizeof(CanMessage_t), NULL);
+  xLEDHeartbeatCAN1 = osThreadNew(vLEDHeartbeat, &ledContextCAN1, &LEDHeartbeatCAN1Attributes);
+  xLEDHeartbeatCAN2 = osThreadNew(vLEDHeartbeat, &ledContextCAN2, &LEDHeartbeatCAN2Attributes);
 
   if (xCAN1RxQueue == NULL || xCAN2RxQueue == NULL) Error_Handler();
   /* USER CODE END RTOS_QUEUES */
@@ -180,13 +185,6 @@ int main(void)
   /* USER CODE END RTOS_EVENTS */
 
   /* USER CODE BEGIN 3 */
-  ledContextCAN1.led = &led_can1;
-  ledContextCAN1.semaphore = xSemaphoreCAN1;
-  ledContextCAN1.timer = xHeartbeatTimerCAN1;
-
-  ledContextCAN2.led = &led_can2;
-  ledContextCAN2.semaphore = xSemaphoreCAN2;
-  ledContextCAN2.timer = xHeartbeatTimerCAN2;
   /* USER CODE END 3 */
 
   /* Start scheduler */