From 8ef0980510adf83b8167726d4697ae5bb65d4d0f Mon Sep 17 00:00:00 2001
From: Erick Ahmed <engineering@erickahmed.com>
Date: Sun, 14 Jun 2026 13:53:40 +0200
Subject: [PATCH] Handle ISR for CANrx by saving message in FIFO buffer

---
 Core/Inc/canlog.h |  1 +
 Core/Src/canlog.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/Core/Inc/canlog.h b/Core/Inc/canlog.h
index 679bcde..db865b1 100644
--- a/Core/Inc/canlog.h
+++ b/Core/Inc/canlog.h
@@ -45,6 +45,7 @@ extern const osThreadAttr_t vLED_CAN2_Heartbeat_attributes;
   * @param  hcan2 Pointer to the CAN2 handle
   */
 void vCANLoggerInit(CAN_HandleTypeDef *hcan1, CAN_HandleTypeDef *hcan2);
+void HAL_CAN_RxFifo0MsgPendingCallback(CAN_HandleTypeDef *hcan);
 void vCANLoggerListen(void *argument);
 void vLEDHeartbeat(void *argument);
 
diff --git a/Core/Src/canlog.c b/Core/Src/canlog.c
index ab296fa..8732b08 100644
--- a/Core/Src/canlog.c
+++ b/Core/Src/canlog.c
@@ -61,6 +61,37 @@ void CAN_Logger_Init(CAN_HandleTypeDef *hcan1, CAN_HandleTypeDef *hcan2)
 }
 /* END CAN_Logger_Init */
 
+/* BEGIN HAL_CAN_RxFifo0MsgPendingCallback */
+/**
+  * @brief  ISR for CAN message pending in FIFO0
+  * @param  argument: Can handle hcan (hcan1 or hcan2)
+  * @retval None
+  */
+void HAL_CAN_RxFifo0MsgPendingCallback(CAN_HandleTypeDef *hcan)
+{
+    /* CODE BEGIN */
+    CanMessage_t message;
+    CAN_RxHeaderTypeDef rxHeader;
+    uint8_t data[8];
+
+    if (HAL_CAN_GetRxMessage(hcan, CAN_RX_FIFO0, &rxHeader, data) != HAL_OK) Error_Handler();
+
+    message.id = rxHeader.ExtId;
+    message.dlc = rxHeader.DLC;
+    message.isExtended = (rxHeader.IDE == CAN_ID_EXT);
+    memcpy(message.payload, data, rxHeader.DLC);
+
+    osMessageQueueId_t queue = (hcan->Instance == CAN1) ? xCAN1RxQueue : xCAN2RxQueue;
+    if (osMessageQueuePut(queue, &message, 0U, 0U) != osOK) Error_Handler();
+    // TODO: better handling: flash error_led on osTimeout, call Error_Handler() when other errors
+
+    // Issue #1: set an event flag for led task
+    // osEventFlagsSet(xCanEventFlags, (hcan->Instance == CAN1) ? 0x01 : 0x02);
+
+    /* CODE END */
+}
+/* END HAL_CAN_RxFifo0MsgPendingCallback */
+
 /* BEGIN vCANLoggerListen */
 /**
   * @brief  Log incoming CAN bus traffic in FIFO buffer