其实CAN还是比较复杂的，如果不明白没有关系，我们可以先从软件层面上来学习怎么使用 CAN，然后再回过头看这些理论知识，这样学习 CAN 应该会比较轻松。 使能 CAN 时钟，将对应引脚复用映射为 CAN 功能 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12; //PA12 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //IO口速度为50MHzGPIO_Init(GPIOA, &GPIO_InitStructure); 设置 CAN 工作模式、波特率等 CAN_InitStructure.CAN_TTCM=DISABLE; //非时间触发通信模式 CAN_InitStructure.CAN_ABOM=DISABLE; //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; //使用报文自动传送 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 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_4tqCAN_InitStructure.CAN_BS1=tbs1; //Tbs1范围CAN_BS1_1tq ~CAN_BS1_16tqCAN_InitStructure.CAN_BS2=tbs2; //Tbs2范围CAN_BS2_1tq ~ CAN_BS2_8tqCAN_InitStructure.CAN_Prescaler=brp; //分频系数(Fdiv)为brp+1 CAN_Init(CAN1, &CAN_InitStructure); // 初始化CAN1设置 CAN 筛选器 CAN_FilterInitStructure.CAN_FilterNumber=0; //过滤器0CAN_FilterInitStructure.CAN_FilterMode=CAN_FilterMode_IdMask; CAN_FilterInitStructure.CAN_FilterScale=CAN_FilterScale_32bit; //32位 CAN_FilterInitStructure.CAN_FilterIdHigh=0x0000;////32位IDCAN_FilterInitStructure.CAN_FilterIdLow=0x0000;CAN_FilterInitStructure.CAN_FilterMaskIdHigh=0x0000;//32位MASKCAN_FilterInitStructure.CAN_FilterMaskIdLow=0x0000; CAN_FilterInitStructure.CAN_FilterFIFOAssignment=CAN_Filter_FIFO0;//过滤器0关联到FIFO0CAN_FilterInitStructure.CAN_FilterActivation=ENABLE; //激活过滤器0CAN_FilterInit(&CAN_FilterInitStructure);//滤波器初始化can.c文件 //CAN初始化//tsjw:重新同步跳跃时间单元.范围:CAN_SJW_1tq~ CAN_SJW_4tq//tbs2:时间段2的时间单元. 范围:CAN_BS2_1tq~CAN_BS2_8tq;//tbs1:时间段1的时间单元. 范围:CAN_BS1_1tq ~CAN_BS1_16tq//brp :波特率分频器.范围:1~1024; tq=(brp)*tpclk1//波特率=Fpclk1/((tbs1+tbs2+1)*brp);//mode:CAN_Mode_Normal,普通模式;CAN_Mode_LoopBack,回环模式;//Fpclk1的时钟在初始化的时候设置为36M,如果设置CAN_Mode_Init(CAN_SJW_1tq,CAN_BS2_8tq,CAN_BS1_9tq,4,CAN_Mode_LoopBack);//则波特率为:36M/((8+9+1)*4)=500Kbps//返回值:0,初始化OK;// 其他,初始化失败;void CAN_Mode_Init(u8 tsjw,u8 tbs2,u8 tbs1,u16 brp,u8 mode){ GPIO_InitTypeDef GPIO_InitStructure; CAN_InitTypeDef CAN_InitStructure; CAN_FilterInitTypeDef CAN_FilterInitStructure; #if CAN_RX0_INT_ENABLE NVIC_InitTypeDef NVIC_InitStructure;#endif RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE); //打开CAN1时钟 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //PA端口时钟打开 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11; //PA11 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //上拉输入模式 GPIO_Init(GPIOA, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12; //PA12 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //IO口速度为50MHz GPIO_Init(GPIOA, &GPIO_InitStructure); //CAN单元设置 CAN_InitStructure.CAN_TTCM=DISABLE; //非时间触发通信模式 CAN_InitStructure.CAN_ABOM=DISABLE; //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; //使用报文自动传送 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 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_4tq CAN_InitStructure.CAN_BS1=tbs1; //Tbs1范围CAN_BS1_1tq ~CAN_BS1_16tq CAN_InitStructure.CAN_BS2=tbs2;//Tbs2范围CAN_BS2_1tq ~ CAN_BS2_8tq CAN_InitStructure.CAN_Prescaler=brp; //分频系数(Fdiv)为brp+1 CAN_Init(CAN1, &CAN_InitStructure); // 初始化CAN1 //配置过滤器 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 USB_LP_CAN1_RX0_IRQHandler(void){ CanRxMsg RxMessage; int i=0; CAN_Receive(CAN1, 0, &RxMessage); for(i=0;i<8;i++) printf("rxbuf[%d]:%d\r\n",i,RxMessage.Data);}#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;u8 CAN_Send_Msg(u8* msg,u8 len){ u8 mbox; u16 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<len;i++) TxMessage.Data=msg; // 第一帧信息 mbox= CAN_Transmit(CAN1, &TxMessage); i=0; while((CAN_TransmitStatus(CAN1, mbox)==CAN_TxStatus_Failed)&&(i<0XFFF))i++; //等待发送结束 if(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;u8 CAN_Receive_Msg(u8 *buf){ u32 i; CanRxMsg RxMessage; if( CAN_MessagePending(CAN1,CAN_FIFO0)==0)return 0; //没有接收到数据,直接退出 CAN_Receive(CAN1, CAN_FIFO0, &RxMessage);//读取数据 for(i=0;i<RxMessage.DLC;i++) buf=RxMessage.Data; return RxMessage.DLC; } can.h #include "system.h" #define CAN_RX0_INT_ENABLE 0 //不使用中断 void CAN_Mode_Init(u8 tsjw,u8 tbs2,u8 tbs1,u16 brp,u8 mode);//CAN初始化 u8 CAN_Send_Msg(u8* msg,u8 len); //发送数据 u8 CAN_Receive_Msg(u8 *buf); //接收数据 #endif main.c #include "system.h"#include "SysTick.h"#include "led.h"#include "usart.h"#include "key.h"#include "can.h" /******************************************************************************** 函 数 名 : main* 函数功能 : 主函数* 输 入 : 无* 输 出 : 无*******************************************************************************/int main(){ u8 i=0,j=0; u8 key; u8 mode=0; u8 res; u8 tbuf[8],char_buf[8]; u8 rbuf[8]; SysTick_Init(72); NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //中断优先级分组 分2组 LED_Init(); USART1_Init(9600); KEY_Init(); CAN_Mode_Init(CAN_SJW_1tq,CAN_BS2_8tq,CAN_BS1_9tq,4,CAN_Mode_Normal);//500Kbps波特率 while(1) { key=KEY_Scan(0); if(key==KEY_UP) //模式切换 { mode=!mode; CAN_Mode_Init(CAN_SJW_1tq,CAN_BS2_8tq,CAN_BS1_9tq,4,mode); if(mode==0) { printf("Normal Mode\r\n"); } else { printf("LoopBack Mode\r\n"); } } if(key==KEY_DOWN) //发送数据 { for(j=0;j<8;j++) { tbuf[j]=j; char_buf[j]=tbuf[j]+0x30; } res=CAN_Send_Msg(tbuf,8); if(res) { printf("Send Failed!\r\n"); } else { printf("发送数据：%s\r\n",char_buf); } } res=CAN_Receive_Msg(rbuf); if(res) { for(j=0;j<res;j++) { char_buf[j]=rbuf[j]+0x30; } printf("接收数据：%s\r\n",char_buf); } i++; if(i%20==0) { led1=!led1; } delay_ms(10); }}[backcolor=rgba(0, 0, 0, 0.03)] |
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