前幾篇有關於CANBus的文章都是利用環回模式去做測試~這一篇會透過Arduino+MCP2515與STM32完成CANBus通訊~

接線

1. MEGA2560 & MCP2515

2. MCP2515 & STM32

Arduino

這部分有已經寫好的庫可以使用，我是使用連結 這個庫來完成的

這邊要注意MCP2515的Baud Rate設定，這邊設定是8MHZ選擇125k bit/s

#include <SPI.h>
#include <mcp2515.h>
struct can_frame canMsg;
struct can_frame canMsg1;
MCP2515 mcp2515(53); //CSS

void setup() {
  canMsg1.can_id  = 0x1876AC23 | CAN_EFF_FLAG;
  canMsg1.can_dlc = 8;
  canMsg1.data[0] = 0x05;
  canMsg1.data[1] = 0x06;
  canMsg1.data[2] = 0x07;
  canMsg1.data[3] = 0x08;
  canMsg1.data[4] = 0x09;
  canMsg1.data[5] = 0x0A;
  canMsg1.data[6] = 0x0B;
  canMsg1.data[7] = 0x0C;
  
  while (!Serial);
  Serial.begin(115200);
  
  mcp2515.reset();
  mcp2515.setBitrate(CAN_125KBPS,MCP_8MHZ);
  //mcp2515.setLoopbackMode();
  mcp2515.setNormalMode();
  Serial.println("********MCP2515&STM32_CAN_Test*********");
  Serial.println("********Send Message*********");
  mcp2515.sendMessage(&canMsg1);
  Serial.print(canMsg1.can_id, HEX); 
  Serial.print(" "); 
  Serial.print(canMsg1.can_dlc, HEX); 
  Serial.print(" ");
    
  for (int i = 0; i<canMsg1.can_dlc; i++)  
  {  
    Serial.print(canMsg1.data[i],HEX);
    Serial.print(" ");
  }
  Serial.println();
  delay(100);
}

void loop() {
  //mcp2515.sendMessage(&canMsg1);
  //delay(100);

  if (mcp2515.readMessage(&canMsg) == MCP2515::ERROR_OK)
  {
    Serial.print(canMsg.can_id, HEX); 
    Serial.print(" "); 
    Serial.print(canMsg.can_dlc, HEX); 
    Serial.print(" ");
    
    for (int i = 0; i<canMsg.can_dlc; i++)  
    {  // print the data
      Serial.print(canMsg.data[i],HEX);
      Serial.print(" ");
    }
    Serial.println();
    delay(100);
    mcp2515.sendMessage(&canMsg1);
    Serial.print(canMsg1.can_id, HEX); 
    Serial.print(" "); 
    Serial.print(canMsg1.can_dlc, HEX); 
    Serial.print(" ");
    for (int i = 0; i<canMsg1.can_dlc; i++) 
    {  // print the data
      Serial.print(canMsg1.data[i],HEX);
      Serial.print(" ");
    }
    Serial.println();
    delay(100);
  }
}

IOC設置

先確認一下系統時鐘是多少 後續再設定TQ與Baud Rate時才不會出錯~
在這邊我系統時鐘是16Mhz

接著來看看CAN的設置
PSC的部分設定為16 TQ會等於1000ns
BS1 選擇4 BS2選擇3 採樣點會落在62.5%
最後Baud Rate會等於125k bit/s (這邊要與另一端設備相同)

全域變數宣告

uint8_t TxBuffer[8] = {0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88};
uint8_t RxBuffer[8];
CAN_TxHeaderTypeDef TxHeader;
CAN_RxHeaderTypeDef RxHeader;
uint32_t TxMailBox;

接收中斷回調函數

void HAL_CAN_RxFifo0MsgPendingCallback(CAN_HandleTypeDef *hcan)
{	
	HAL_CAN_GetRxMessage(&hcan1, CAN_RX_FIFO0, &RxHeader, RxBuffer);
}

設置Filter模式 這邊我選擇LIST也就是所有ID必須完全相符才會接收

void ConfigFliter(void)
{
	CAN_FilterTypeDef CAN1Filter;
	CAN1Filter.FilterActivation = CAN_FILTER_ENABLE;
	CAN1Filter.FilterFIFOAssignment = CAN_RX_FIFO0;
	CAN1Filter.FilterMode = CAN_FILTERMODE_IDLIST;
	CAN1Filter.FilterScale = CAN_FILTERSCALE_32BIT;
	CAN1Filter.FilterBank = 0;
	CAN1Filter.FilterIdHigh = ((0x1876AC23<<3)>>16) & 0xffff;
	CAN1Filter.FilterIdLow =((0x1876AC23<<3)& 0xffff) | CAN_ID_EXT;
	CAN1Filter.SlaveStartFilterBank = 0;
	HAL_CAN_ConfigFilter(&hcan1, &CAN1Filter);
}

main

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_USART2_UART_Init();
  MX_CAN1_Init();
  /* USER CODE BEGIN 2 */
  ConfigFliter();
  HAL_CAN_Start(&hcan1);
  HAL_CAN_ActivateNotification(&hcan1, CAN_IT_RX_FIFO0_MSG_PENDING);
  TxHeader.DLC =8;
  TxHeader.ExtId = 0x08C53451;
  TxHeader.IDE = CAN_ID_EXT;
  TxHeader.RTR = CAN_RTR_DATA;
  TxHeader.TransmitGlobalTime = DISABLE;
  HAL_CAN_AddTxMessage(&hcan1, &TxHeader, TxBuffer, &TxMailBox);
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

測試結果

這邊我先將MCP2515做環回測試確定傳送與接收正常後才與STM32對接做測試~

下圖為Arduino & MCP2515 LoopBack 測試畫面

Arduino傳送端

STM32所接收到的資料

由於我只有一塊STM32，所以用MCP2515來當作另一端設備，手邊有兩塊的話可以直接將CANRX與另一端TX相連做測試就可以了~