STM32F042 CAN使用例子

代码如下：

#include "mycan.h"

//CAN初始化
//tsjw:重新同步跳跃时间单元.范围:1~3; CAN_SJW_1tq	 CAN_SJW_2tq CAN_SJW_3tq CAN_SJW_4tq
//tbs2:时间段2的时间单元.范围:1~8;
//tbs1:时间段1的时间单元.范围:1~16;	  CAN_BS1_1tq ~CAN_BS1_16tq
//brp :波特率分频器.范围:1~1024;(实际要加1,也就是1~1024) tq=(brp)*tpclk1
//注意以上参数任何一个都不能设为0,否则会乱.
//波特率=Fpclk1/((tsjw+tbs1+tbs2)*brp);
//mode:0,普通模式;1,回环模式;
//Fpclk1的时钟在初始化的时候设置为36M,如果设置CAN_Normal_Init(1,8,7,5,1);
//则波特率为: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时钟	                   											 
	  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时钟	

    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_PuPd  = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
		
	  CAN_DeInit(CAN);
 	//CAN单元设置
		CAN_InitStructure.CAN_TTCM=DISABLE;						 //非时间触发通信模式  //
		CAN_InitStructure.CAN_ABOM=ENABLE;						 //软件自动离线管理	 //
		CAN_InitStructure.CAN_AWUM=DISABLE;						 //睡眠模式通过软件唤醒(清除CAN->MCR的SLEEP位)//
		CAN_InitStructure.CAN_NART=ENABLE;						 	//禁止报文自动传送 //
		CAN_InitStructure.CAN_RFLM=DISABLE;						 //报文不锁定,新的覆盖旧的 // 
		CAN_InitStructure.CAN_TXFP=DISABLE;						 //优先级由报文标识符决定 //
		CAN_InitStructure.CAN_Mode= mode;	         //模式设置： mode:0,普通模式;1,回环模式; //
  	//设置波特率
  	CAN_InitStructure.CAN_SJW=tsjw;				//重新同步跳跃宽度(Tsjw)为tsjw+1个时间单位  CAN_SJW_1tq	 CAN_SJW_2tq CAN_SJW_3tq CAN_SJW_4tq
  	CAN_InitStructure.CAN_BS1=tbs1; //Tbs1=tbs1+1个时间单位CAN_BS1_1tq ~CAN_BS1_16tq
  	CAN_InitStructure.CAN_BS2=tbs2;//Tbs2=tbs2+1个时间单位CAN_BS2_1tq ~	CAN_BS2_8tq
  	CAN_InitStructure.CAN_Prescaler=brp;            //分频系数(Fdiv)为brp+1	//
  	CAN_Init(CAN, &CAN_InitStructure);            // 初始化CAN1 

		CAN_FilterInitStructure.CAN_FilterNumber=0;	  //过滤器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;//过滤器0关联到FIFO0
		CAN_FilterInitStructure.CAN_FilterActivation=ENABLE; //激活过滤器0

		CAN_FilterInit(&CAN_FilterInitStructure);//滤波器初始化
#if CAN_RX0_INT_ENABLE
	
		CAN_ITConfig(CAN1,CAN_IT_FMP0,ENABLE);//FIFO0消息挂号中断允许.		    

		NVIC_InitStructure.NVIC_IRQChannel = USB_LP_CAN1_RX0_IRQn;
		NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;     // 主优先级为1
		NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;            // 次优先级为0
		NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
		NVIC_Init(&NVIC_InitStructure);
#endif
}
#if CAN_RX0_INT_ENABLE	//使能RX0中断
//中断服务函数			    
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发送一组数据(固定格式:ID为0X12,标准帧,数据帧)	
//len:数据长度(最大为8)				     
//msg:数据指针,最大为8个字节.
//返回值:0,成功;
//		 其他,失败;
uint8_t Can_Send_Msg(uint8_t* msg,uint8_t len)
{	
  uint8_t mbox;
  uint16_t i=0;
  CanTxMsg TxMessage;
  TxMessage.StdId=0x12;					 // 标准标识符为0
  TxMessage.ExtId=0x12;				 // 设置扩展标示符（29位）
  TxMessage.IDE=0;			 // 使用扩展标识符
  TxMessage.RTR=0;		 // 消息类型为数据帧，一帧8位
  TxMessage.DLC=len;							 // 发送两帧信息
  for(i=0;i= 0XFFF)return 1;
  return 0;		
}
//can口接收数据查询
//buf:数据缓存区;	 
//返回值:0,无数据被收到;
//		 其他,接收的数据长度;
uint8_t Can_Receive_Msg(uint8_t *buf)
{		   		   
 	uint32_t i;
	CanRxMsg RxMessage;
    if( CAN_MessagePending(CAN,CAN_FIFO0)==0)return 0;		//没有接收到数据,直接退出 
    CAN_Receive(CAN, CAN_FIFO0, &RxMessage);//读取数据	
    for(i=0;i<8;i++)
    buf[i]=RxMessage.Data[i];  
	return RxMessage.DLC;	
}

注意：一定要根据自己的封装来设置
SYSCFG->CFGR1 |= SYSCFG_CFGR1_PA11_PA12_RMP;
如果不设置 CAN_Init(CAN, &CAN_InitStructure);会初始化失败