STM32 教學系列 第 10 節：CANbus 通訊（兩板間通訊）

🎯 學習目標 
 
 理解 CAN 協定基礎 - 掌握識別符、優先級仲裁與訊息過濾 
 配置 TJA1050 收發器 - 實現 Nucleo 與 Nucleo 的 CAN 通訊 
 實現雙板訊息收發 - 一片做發送方，另一片做接收方 
 
 
 🎓 CAN 協定基礎 
 CAN 是什麼？ 
 CAN (Controller Area Network) 是車用工業級網路協定。特點： 
 
 強抗干擾 ：差分信號設計 
 實時性好 ：優先級仲裁確保關鍵訊息先傳 
 多節點 ：最多 127 個節點共享一條總線 
 長距離 ：可達 40km（低速）或 1km（高速） 
 
 CAN 消息結構 
 
 
 
 欄位 
 長度 
 說明 
 
 
 
 
 ID 
 11 bit（標準）/ 29 bit（擴展） 
 訊息識別符，用於優先級仲裁 
 
 
 DLC 
 4 bit 
 資料長度碼（0-8 bytes） 
 
 
 DATA 
 0-8 bytes 
 實際負載資料 
 
 
 CRC 
 15 bit 
 循環冗餘碼（硬體自動計算） 
 
 
 
 CAN 的 2 條信號線 
 
 
 
 訊號 
 說明 
 
 
 
 
 CAN_H 
 CAN 高位線 
 
 
 CAN_L 
 CAN 低位線 
 
 
 GND 
 共同接地 
 
 
 
 STM32F446 CAN 資源 
 
 
 
 特性 
 規格 
 
 
 
 
 CAN 模組 
 2 個（CAN1、CAN2） 
 
 
 最高速度 
 1 Mbps 
 
 
 訊息濾波器 
 14 個過濾器組 
 
 
 接收 FIFO 
 2 個（每個 3 訊息） 
 
 
 傳輸郵箱 
 3 個 
 
 
 
 
 🛠️ 硬體接線 
 所需元件 
 
 
 
 元件 
 數量 
 說明 
 
 
 
 
 Nucleo-F446RC 
 2 
 一發一收 
 
 
 TJA1050 CAN 收發器 
 2 
 轉換 CAN 信號 
 
 
 120Ω 終端電阻 
 2 
 CAN 總線兩端各 1 
 
 
 跳線 
 多條 
 連接所有元件 
 
 
 
 CAN 總線接線 
 Nucleo 1 (發送方) TJA1050 收發器 CAN 總線 TJA1050 收發器 Nucleo 2 (接收方)
───────────────── ───────────────── ────────── ───────────────── ─────────────────
PB8 (CAN1_RX) ───────→ RXD ← RXD ─── PB8 (CAN1_RX)
PB9 (CAN1_TX) ←────── TXD ──→ TXD ─── PB9 (CAN1_TX)
3.3V ──────────────→ VCC ← VCC ──────── 3.3V
GND ───────────────→ GND ← GND ──────── GND
 ┌──────→ CANH ═════════════════════════════════════════════════ CANH ────┐
 │ │
 │ [120Ω] ← 終端電阻 [120Ω] ← 終端電阻 │
 │ │ │ │
 │ GND GND │
 │ │
 └──────→ CANL ═════════════════════════════════════════════════ CANL ────┘
 
 接線表 
 | Nucleo PB8 | → | TJA1050 RXD |
| Nucleo PB9 | ← | TJA1050 TXD |
| Nucleo 3.3V | → | TJA1050 VCC |
| Nucleo GND | → | TJA1050 GND |
| TJA1050 CANH | ═ | CAN 總線 H |
| TJA1050 CANL | ═ | CAN 總線 L | 
 
 ⚙️ CubeMX 配置步驟 
 步驟 1：啟用 CAN1（兩片板都設定相同） 
 
 開啟 CubeMX 
 在 Pinout 圖中選擇：
 
 PB8 ：配置為 CAN1_RX 
 PB9 ：配置為 CAN1_TX 
 
 
 
 步驟 2：配置 CAN 參數 
 
 
 在左側選擇 Connectivity → CAN1 
 
 
 Activated ：勾選啟用 
 
 
 Parameter Settings 中設定： 
 
 Mode ：Normal Mode 
 Prescaler ：8（波特率 = 168MHz / 8 / 13 ≈ 1.615 Mbps，調整至 1 Mbps） 
 Time Quanta in Bit Segment 1 ：11 
 Time Quanta in Bit Segment 2 ：2 
 Resynchronization Jump Width ：1 
 
 
 
 Filter Settings ：配置過濾器 
 
 Number of Master Filters ：14 
 Filters Configuration ：
 
 Filter ID ：0x000（接收所有 ID） 
 Filter Mask ：0x000 
 Filter FIFO Assignment ：FIFO0 
 Filter Activation ：Enable 
 
 
 
 
 
 步驟 3：啟用中斷 
 NVIC Settings 中勾選： 
 
 CAN1 RX0 interrupt 
 CAN1 TX interrupt 
 
 步驟 4：生成程式碼 
 點擊 Generate Code 
 
 💻 完整程式碼 
 發送方 (Nucleo 1)：main.c 
 /* STM32 Lesson 10 - CAN Bus (Sender)
 * 功能：發送 CAN 訊息到另一片 Nucleo
 * 難度：中級
 */

#include "main.h"
#include "can.h"
#include "usart.h"
#include <stdio.h>
#include <string.h>

#define CAN_ID_TEST 0x123 /* CAN 訊息 ID */

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_CAN1_Init(void);
static void MX_USART1_UART_Init(void);
void UART_Print(const char *format, ...);

CAN_HandleTypeDef hcan1;
UART_HandleTypeDef huart1;

int main(void)
{
 HAL_Init();
 SystemClock_Config();
 MX_GPIO_Init();
 MX_CAN1_Init();
 MX_USART1_UART_Init();

 UART_Print("\r\n=== CAN Bus Sender ===\r\n");

 CAN_TxHeaderTypeDef TxHeader;
 uint8_t TxData[8];
 uint32_t TxMailbox;

 /* 配置發送訊息頭 */
 TxHeader.StdId = CAN_ID_TEST;
 TxHeader.IDE = CAN_ID_STD; /* 標準 ID */
 TxHeader.RTR = CAN_RTR_DATA; /* 資料訊息（非遠程） */
 TxHeader.DLC = 8; /* 資料長度 8 bytes */

 uint32_t counter = 0;

 while (1)
 {
 /* 準備發送資料 */
 TxData[0] = (counter >> 24) & 0xFF;
 TxData[1] = (counter >> 16) & 0xFF;
 TxData[2] = (counter >> 8) & 0xFF;
 TxData[3] = counter & 0xFF;
 TxData[4] = 0xAA;
 TxData[5] = 0xBB;
 TxData[6] = 0xCC;
 TxData[7] = 0xDD;

 /* 發送訊息 */
 if (HAL_CAN_AddTxMessage(&hcan1, &TxHeader, TxData, &TxMailbox) == HAL_OK)
 {
 UART_Print("CAN Sent: ID=0x%03X, Data=[%02X %02X %02X %02X %02X %02X %02X %02X]\r\n",
 CAN_ID_TEST,
 TxData[0], TxData[1], TxData[2], TxData[3],
 TxData[4], TxData[5], TxData[6], TxData[7]);
 counter++;
 }
 else
 {
 UART_Print("CAN Send Failed!\r\n");
 }

 HAL_Delay(1000);
 }
}

void UART_Print(const char *format, ...)
{
 char buffer[100];
 va_list args;
 va_start(args, format);
 vsnprintf(buffer, sizeof(buffer), format, args);
 va_end(args);
 
 HAL_UART_Transmit(&huart1, (uint8_t *)buffer, strlen(buffer), HAL_MAX_DELAY);
}

void SystemClock_Config(void)
{
 RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

 __HAL_RCC_PWR_CLK_ENABLE();
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
 RCC_OscInitStruct.HSEState = RCC_HSE_ON;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
 RCC_OscInitStruct.PLL.PLLM = 8;
 RCC_OscInitStruct.PLL.PLLN = 336;
 RCC_OscInitStruct.PLL.PLLP = 2;
 RCC_OscInitStruct.PLL.PLLQ = 7;

 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
 Error_Handler();

 RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
 | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;

 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
 Error_Handler();
}

static void MX_GPIO_Init(void)
{
 __HAL_RCC_GPIOA_CLK_ENABLE();
}

static void MX_CAN1_Init(void)
{
 hcan1.Instance = CAN1;
 hcan1.Init.Prescaler = 6;
 hcan1.Init.Mode = CAN_MODE_NORMAL;
 hcan1.Init.SyncJumpWidth = CAN_SJW_1TQ;
 hcan1.Init.TimeSeg1 = CAN_BS1_11TQ;
 hcan1.Init.TimeSeg2 = CAN_BS2_2TQ;
 hcan1.Init.TimeTriggeredMode = DISABLE;
 hcan1.Init.AutoBusOff = DISABLE;
 hcan1.Init.AutoWakeUp = DISABLE;
 hcan1.Init.AutoRetransmission = ENABLE;
 hcan1.Init.ReceiveFifoLocked = DISABLE;
 hcan1.Init.TransmitFifoPriority = DISABLE;

 if (HAL_CAN_Init(&hcan1) != HAL_OK)
 Error_Handler();

 HAL_CAN_Start(&hcan1);
}

static void MX_USART1_UART_Init(void)
{
 huart1.Instance = USART1;
 huart1.Init.BaudRate = 115200;
 huart1.Init.WordLength = UART_WORDLENGTH_8B;
 huart1.Init.StopBits = UART_STOPBITS_1;
 huart1.Init.Parity = UART_PARITY_NONE;
 huart1.Init.Mode = UART_MODE_TX_RX;

 if (HAL_UART_Init(&huart1) != HAL_OK)
 Error_Handler();
}

void Error_Handler(void)
{
 while(1);
}
 
 接收方 (Nucleo 2)：main.c 
 /* STM32 Lesson 10 - CAN Bus (Receiver)
 * 功能：接收另一片 Nucleo 的 CAN 訊息
 * 難度：中級
 */

#include "main.h"
#include "can.h"
#include "usart.h"
#include <stdio.h>
#include <string.h>

#define CAN_ID_TEST 0x123

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_CAN1_Init(void);
static void MX_USART1_UART_Init(void);
void UART_Print(const char *format, ...);

CAN_HandleTypeDef hcan1;
UART_HandleTypeDef huart1;

int main(void)
{
 HAL_Init();
 SystemClock_Config();
 MX_GPIO_Init();
 MX_CAN1_Init();
 MX_USART1_UART_Init();

 UART_Print("\r\n=== CAN Bus Receiver ===\r\n");

 CAN_FilterTypeDef sFilterConfig;
 CAN_RxHeaderTypeDef RxHeader;
 uint8_t RxData[8];

 /* 配置接收過濾器 */
 sFilterConfig.FilterBank = 0;
 sFilterConfig.FilterMode = CAN_FILTERMODE_IDMASK;
 sFilterConfig.FilterScale = CAN_FILTERSCALE_32BIT;
 sFilterConfig.FilterIdHigh = (CAN_ID_TEST << 5) >> 16;
 sFilterConfig.FilterIdLow = (CAN_ID_TEST << 5) & 0xFFFF;
 sFilterConfig.FilterMaskIdHigh = 0xFFFF;
 sFilterConfig.FilterMaskIdLow = 0xFFFF;
 sFilterConfig.FilterFIFOAssignment = CAN_RX_FIFO0;
 sFilterConfig.FilterActivation = ENABLE;

 if (HAL_CAN_ConfigFilter(&hcan1, &sFilterConfig) != HAL_OK)
 Error_Handler();

 if (HAL_CAN_Start(&hcan1) != HAL_OK)
 Error_Handler();

 /* 啟用接收中斷 */
 if (HAL_CAN_ActivateNotification(&hcan1, CAN_IT_RX_FIFO0_MSG_PENDING) != HAL_OK)
 Error_Handler();

 UART_Print("Waiting for CAN messages...\r\n");

 while (1)
 {
 if (HAL_CAN_GetRxFifoFillLevel(&hcan1, CAN_RX_FIFO0) > 0)
 {
 if (HAL_CAN_GetRxMessage(&hcan1, CAN_RX_FIFO0, &RxHeader, RxData) == HAL_OK)
 {
 UART_Print("CAN Received: ID=0x%03X, DLC=%d, Data=[%02X %02X %02X %02X %02X %02X %02X %02X]\r\n",
 RxHeader.StdId, RxHeader.DLC,
 RxData[0], RxData[1], RxData[2], RxData[3],
 RxData[4], RxData[5], RxData[6], RxData[7]);
 }
 }
 HAL_Delay(100);
 }
}

void UART_Print(const char *format, ...)
{
 char buffer[100];
 va_list args;
 va_start(args, format);
 vsnprintf(buffer, sizeof(buffer), format, args);
 va_end(args);
 
 HAL_UART_Transmit(&huart1, (uint8_t *)buffer, strlen(buffer), HAL_MAX_DELAY);
}

void SystemClock_Config(void)
{
 RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

 __HAL_RCC_PWR_CLK_ENABLE();
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
 RCC_OscInitStruct.HSEState = RCC_HSE_ON;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
 RCC_OscInitStruct.PLL.PLLM = 8;
 RCC_OscInitStruct.PLL.PLLN = 336;
 RCC_OscInitStruct.PLL.PLLP = 2;
 RCC_OscInitStruct.PLL.PLLQ = 7;

 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
 Error_Handler();

 RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
 | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;

 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
 Error_Handler();
}

static void MX_GPIO_Init(void)
{
 __HAL_RCC_GPIOA_CLK_ENABLE();
}

static void MX_CAN1_Init(void)
{
 hcan1.Instance = CAN1;
 hcan1.Init.Prescaler = 6;
 hcan1.Init.Mode = CAN_MODE_NORMAL;
 hcan1.Init.SyncJumpWidth = CAN_SJW_1TQ;
 hcan1.Init.TimeSeg1 = CAN_BS1_11TQ;
 hcan1.Init.TimeSeg2 = CAN_BS2_2TQ;
 hcan1.Init.TimeTriggeredMode = DISABLE;
 hcan1.Init.AutoBusOff = DISABLE;
 hcan1.Init.AutoWakeUp = DISABLE;
 hcan1.Init.AutoRetransmission = ENABLE;
 hcan1.Init.ReceiveFifoLocked = DISABLE;
 hcan1.Init.TransmitFifoPriority = DISABLE;

 if (HAL_CAN_Init(&hcan1) != HAL_OK)
 Error_Handler();
}

static void MX_USART1_UART_Init(void)
{
 huart1.Instance = USART1;
 huart1.Init.BaudRate = 115200;
 huart1.Init.WordLength = UART_WORDLENGTH_8B;
 huart1.Init.StopBits = UART_STOPBITS_1;
 huart1.Init.Parity = UART_PARITY_NONE;
 huart1.Init.Mode = UART_MODE_TX_RX;

 if (HAL_UART_Init(&huart1) != HAL_OK)
 Error_Handler();
}

void Error_Handler(void)
{
 while(1);
}
 
 
 🔍 測試與除錯 
 預期結果 
 ✅ 發送方 UART 輸出 ： 
 === CAN Bus Sender ===
CAN Sent: ID=0x123, Data=[00 00 00 00 AA BB CC DD]
CAN Sent: ID=0x123, Data=[00 00 00 01 AA BB CC DD]
CAN Sent: ID=0x123, Data=[00 00 00 02 AA BB CC DD]
 
 ✅ 接收方 UART 輸出 ： 
 === CAN Bus Receiver ===
Waiting for CAN messages...
CAN Received: ID=0x123, DLC=8, Data=[00 00 00 00 AA BB CC DD]
CAN Received: ID=0x123, DLC=8, Data=[00 00 00 01 AA BB CC DD]
CAN Received: ID=0x123, DLC=8, Data=[00 00 00 02 AA BB CC DD]
 
 常見問題 
 
 
 
 問題 
 原因 
 解決 
 
 
 
 
 無法接收 
 波特率配置錯誤 
 重新計算 Prescaler/TimeSeg 
 
 
 訊息丟失 
 CAN 總線終端電阻缺少 
 確保兩端各有 120Ω 電阻 
 
 
 發送失敗 
 郵箱滿 
 檢查 HAL_CAN_GetTxMailboxesFreeLevel() 
 
 
 
 
 🔗 延伸學習 
 下節預覽 - 第 11 節：RS-485 通訊 
 第 11 節將實現： 
 
 RS-485 差分信號 
 多設備半雙工通訊 
 收發模式自動切換 
 
 
 ✨ CAN 雙板通訊完成！🚀