STM32F042 CAN使用例子

代碼如下：

#include "mycan.h"

//CAN初始化
//tsjw:重新同步跳躍時間單元.範圍:1~3; CAN_SJW_1tq	 CAN_SJW_2tq CAN_SJW_3tq CAN_SJW_4tq
//tbs2:時間段2的時間單元.範圍:1~8;
//tbs1:時間段1的時間單元.範圍:1~16;	  CAN_BS1_1tq ~CAN_BS1_16tq
//brp :波特率分頻器.範圍:1~1024;(實際要加1,也就是1~1024) tq=(brp)*tpclk1
//注意以上參數任何一個都不能設爲0,否則會亂.
//波特率=Fpclk1/((tsjw+tbs1+tbs2)*brp);
//mode:0,普通模式;1,迴環模式;
//Fpclk1的時鐘在初始化的時候設置爲36M,如果設置CAN_Normal_Init(1,8,7,5,1);
//則波特率爲:48M/((1+8+7)*5)=450Kbps

void CAN_Mode_Init(uint8_t tsjw,uint8_t tbs2,uint8_t tbs1,uint16_t brp,uint8_t mode)
{

	GPIO_InitTypeDef GPIO_InitStructure; 
	CAN_InitTypeDef        CAN_InitStructure;
 	CAN_FilterInitTypeDef  CAN_FilterInitStructure;
#if CAN_RX0_INT_ENABLE 
   	NVIC_InitTypeDef  NVIC_InitStructure;
#endif
		
		RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
		RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);//使能PORTA時鐘	                   											 
	  SYSCFG->CFGR1 |= SYSCFG_CFGR1_PA11_PA12_RMP;                  //RMAP	
	  GPIO_PinAFConfig(GPIOA,GPIO_PinSource12,GPIO_AF_4);
		GPIO_PinAFConfig(GPIOA,GPIO_PinSource11,GPIO_AF_4);
  	RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN, ENABLE);//使能CAN時鐘	

    GPIO_InitStructure.GPIO_Pin   = GPIO_Pin_11|GPIO_Pin_12;
    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
		
	  CAN_DeInit(CAN);
 	//CAN單元設置
		CAN_InitStructure.CAN_TTCM=DISABLE;						 //非時間觸發通信模式  //
		CAN_InitStructure.CAN_ABOM=ENABLE;						 //軟件自動離線管理	 //
		CAN_InitStructure.CAN_AWUM=DISABLE;						 //睡眠模式通過軟件喚醒(清除CAN->MCR的SLEEP位)//
		CAN_InitStructure.CAN_NART=ENABLE;						 	//禁止報文自動傳送 //
		CAN_InitStructure.CAN_RFLM=DISABLE;						 //報文不鎖定,新的覆蓋舊的 // 
		CAN_InitStructure.CAN_TXFP=DISABLE;						 //優先級由報文標識符決定 //
		CAN_InitStructure.CAN_Mode= mode;	         //模式設置： mode:0,普通模式;1,迴環模式; //
  	//設置波特率
  	CAN_InitStructure.CAN_SJW=tsjw;				//重新同步跳躍寬度(Tsjw)爲tsjw+1個時間單位  CAN_SJW_1tq	 CAN_SJW_2tq CAN_SJW_3tq CAN_SJW_4tq
  	CAN_InitStructure.CAN_BS1=tbs1; //Tbs1=tbs1+1個時間單位CAN_BS1_1tq ~CAN_BS1_16tq
  	CAN_InitStructure.CAN_BS2=tbs2;//Tbs2=tbs2+1個時間單位CAN_BS2_1tq ~	CAN_BS2_8tq
  	CAN_InitStructure.CAN_Prescaler=brp;            //分頻係數(Fdiv)爲brp+1	//
  	CAN_Init(CAN, &CAN_InitStructure);            // 初始化CAN1 

		CAN_FilterInitStructure.CAN_FilterNumber=0;	  //過濾器0
		CAN_FilterInitStructure.CAN_FilterMode=CAN_FilterMode_IdMask; 
		CAN_FilterInitStructure.CAN_FilterScale=CAN_FilterScale_32bit; //32位 
		CAN_FilterInitStructure.CAN_FilterIdHigh=0x0000;////32位ID
		CAN_FilterInitStructure.CAN_FilterIdLow=0x0000;
		CAN_FilterInitStructure.CAN_FilterMaskIdHigh=0x0000;//32位MASK
		CAN_FilterInitStructure.CAN_FilterMaskIdLow=0x0000;
		CAN_FilterInitStructure.CAN_FilterFIFOAssignment=CAN_Filter_FIFO0;//過濾器0關聯到FIFO0
		CAN_FilterInitStructure.CAN_FilterActivation=ENABLE; //激活過濾器0

		CAN_FilterInit(&CAN_FilterInitStructure);//濾波器初始化
#if CAN_RX0_INT_ENABLE
	
		CAN_ITConfig(CAN1,CAN_IT_FMP0,ENABLE);//FIFO0消息掛號中斷允許.		    

		NVIC_InitStructure.NVIC_IRQChannel = USB_LP_CAN1_RX0_IRQn;
		NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;     // 主優先級爲1
		NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;            // 次優先級爲0
		NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
		NVIC_Init(&NVIC_InitStructure);
#endif
}
#if CAN_RX0_INT_ENABLE	//使能RX0中斷
//中斷服務函數			    
void CEC_CAN_IRQHandler(void)
{
		CanRxMsg RxMessage;
		int i=0;
		CAN_Receive(CAN, 0, &RxMessage);
		//for(i=0;i<8;i++)
		//printf("rxbuf[%d]:%d\r\n",i,RxMessage.Data[i]);
}
#endif

//can發送一組數據(固定格式:ID爲0X12,標準幀,數據幀)	
//len:數據長度(最大爲8)				     
//msg:數據指針,最大爲8個字節.
//返回值:0,成功;
//		 其他,失敗;
uint8_t Can_Send_Msg(uint8_t* msg,uint8_t len)
{	
  uint8_t mbox;
  uint16_t i=0;
  CanTxMsg TxMessage;
  TxMessage.StdId=0x12;					 // 標準標識符爲0
  TxMessage.ExtId=0x12;				 // 設置擴展標示符（29位）
  TxMessage.IDE=0;			 // 使用擴展標識符
  TxMessage.RTR=0;		 // 消息類型爲數據幀，一幀8位
  TxMessage.DLC=len;							 // 發送兩幀信息
  for(i=0;i<len;i++)
  TxMessage.Data[i]=msg[i];				 // 第一幀信息          
  mbox= CAN_Transmit(CAN, &TxMessage);   
  i=0;
  while((CAN_TransmitStatus(CAN, mbox)==CAN_TxStatus_Failed)&&(i < 0XFFF))i++;	//等待發送結束
  if(i >= 0XFFF)return 1;
  return 0;		
}
//can口接收數據查詢
//buf:數據緩存區;	 
//返回值:0,無數據被收到;
//		 其他,接收的數據長度;
uint8_t Can_Receive_Msg(uint8_t *buf)
{		   		   
 	uint32_t i;
	CanRxMsg RxMessage;
    if( CAN_MessagePending(CAN,CAN_FIFO0)==0)return 0;		//沒有接收到數據,直接退出 
    CAN_Receive(CAN, CAN_FIFO0, &RxMessage);//讀取數據	
    for(i=0;i<8;i++)
    buf[i]=RxMessage.Data[i];  
	return RxMessage.DLC;	
}

注意：一定要根據自己的封裝來設置
SYSCFG->CFGR1 |= SYSCFG_CFGR1_PA11_PA12_RMP;
如果不設置 CAN_Init(CAN, &CAN_InitStructure);會初始化失敗