STM32 CAN使用
CAN工作模式:
CAN_Mode_Silent:静默模式，简单理解收到数据不发送应答信号。
在静默模式下，总线必须要有2个或2个以上的节点，才能收到数据，个 人理解有应答信号stm32的can内核才认为只是一个完整的数据。
CAN波特率设置：
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
BPS = AHB1_CLOCK / (tbs1 + tbs2 + brp + 1);
CAN滤波与FIFO，直接看代码如下：
u8 CAN1_Mode_Init(u8 tsjw,u8 tbs2,u8 tbs1,u16 brp,u8 mode)
{
int ext_id = 0x000000FF;//期望 想要看到的ID，例如 我先要ID 后2位时FF的数据，那么ext_id = 0x000000FF即可
GPIO_InitTypeDef GPIO_InitStructure;
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
//使能相关时钟
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);//使能PORTD时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);//使能CAN1时钟
//初始化GPIO
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0| GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;//复用功能
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;//推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;//100MHz
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;//上拉
GPIO_Init(GPIOD, &GPIO_InitStructure);//初始化PD0,PD1
//引脚复用映射配置
GPIO_PinAFConfig(GPIOD,GPIO_PinSource0,GPIO_AF_CAN1); //GPIOD0复用为CAN1
GPIO_PinAFConfig(GPIOD,GPIO_PinSource1,GPIO_AF_CAN1); //GPIOD1复用为CAN1
//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; //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
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
//设置屏蔽寄存器，这里当标识符寄存器
CAN_FilterInitStructure.CAN_FilterIdHigh = ((ext_id<<3)>>16) & 0xffff; //设置屏蔽寄存器高字节
CAN_FilterInitStructure.CAN_FilterIdLow = ((ext_id<<3)& 0xffff) | CAN_ID_EXT; //设置屏蔽寄存器低字节
//设置标识符寄存器
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = ((ext_id<<3)>>16) & 0xffff; //设置屏蔽寄存器高字节
CAN_FilterInitStructure.CAN_FilterMaskIdLow = ((ext_id<<3)& 0xffff) | CAN_ID_EXT; //设置屏蔽寄存器低字节
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
CAN_ITConfig(CAN1,CAN_IT_FMP0,ENABLE);//FIFO0消息挂号中断允许.
NVIC_InitStructure.NVIC_IRQChannel = 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);
//配置过滤器2
ext_id = 0x00000000;
CAN_FilterInitStructure.CAN_FilterNumber = 1; //过滤器1
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit; //32位
//设置屏蔽寄存器，这里当标识符寄存器
CAN_FilterInitStructure.CAN_FilterIdHigh = ((ext_id<<3)>>16) & 0xffff; //设置屏蔽寄存器高字节
CAN_FilterInitStructure.CAN_FilterIdLow = ((ext_id<<3)& 0xffff) | CAN_ID_EXT; //设置屏蔽寄存器低字节
//设置标识符寄存器
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = ((ext_id<<3)>>16) & 0xffff; //设置屏蔽寄存器高字节
CAN_FilterInitStructure.CAN_FilterMaskIdLow = ((ext_id<<3)& 0xffff) | CAN_ID_EXT; //设置屏蔽寄存器低字节
CAN_FilterInitStructure.CAN_FilterFIFOAssignment = CAN_Filter_FIFO1;//过滤器0关联到FIFO1
CAN_FilterInitStructure.CAN_FilterActivation = ENABLE; //激活过滤器0
CAN_FilterInit(&CAN_FilterInitStructure);//滤波器初始化
CAN_ITConfig(CAN1,CAN_IT_FMP1,ENABLE);//FIFO1消息挂号中断允许.
NVIC_InitStructure.NVIC_IRQChannel = CAN1_RX1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; // 主优先级为1
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; // 次优先级为3
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
return 0;
}
u8 CAN2_Mode_Init(u8 tsjw,u8 tbs2,u8 tbs1,u16 brp,u8 mode)
{
int ext_id = 0x00000000;//期望 想要看到的ID，例如 我先要ID 后2位时FF的数据，那么ext_id = 0x000000FF即可
GPIO_InitTypeDef GPIO_InitStructure;
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
//使能相关时钟
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);//使能PORTB时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN2, ENABLE);//使能CAN2时钟
//初始化GPIO
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12| GPIO_Pin_13;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;//复用功能
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;//推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;//100MHz
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;//上拉
GPIO_Init(GPIOB, &GPIO_InitStructure);//初始化PB12,PB13
//引脚复用映射配置
GPIO_PinAFConfig(GPIOB,GPIO_PinSource12,GPIO_AF_CAN2); //GPIOB12复用为CAN2
GPIO_PinAFConfig(GPIOB,GPIO_PinSource13,GPIO_AF_CAN2); //GPIOB13复用为CAN2
//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; //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
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(CAN2, &CAN_InitStructure); // 初始化CAN2
//配置过滤器
CAN_FilterInitStructure.CAN_FilterNumber=14; //过滤器14
CAN_FilterInitStructure.CAN_FilterMode=CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale=CAN_FilterScale_32bit; //32位
//设置屏蔽寄存器，这里当标识符寄存器
CAN_FilterInitStructure.CAN_FilterIdHigh=((ext_id<<3)>>16) & 0xffff; //设置屏蔽寄存器高字节
CAN_FilterInitStructure.CAN_FilterIdLow=((ext_id<<3)& 0xffff) | CAN_ID_EXT; //设置屏蔽寄存器低字节
//设置标识符寄存器
CAN_FilterInitStructure.CAN_FilterMaskIdHigh = ((ext_id<<3)>>16) & 0xffff; //设置屏蔽寄存器高字节
CAN_FilterInitStructure.CAN_FilterMaskIdLow = ((ext_id<<3)& 0xffff) | CAN_ID_EXT; //设置屏蔽寄存器低字节
CAN_FilterInitStructure.CAN_FilterFIFOAssignment=CAN_Filter_FIFO0;//过滤器1关联到FIFO1
CAN_FilterInitStructure.CAN_FilterActivation=ENABLE; //激活过滤器0
CAN_FilterInit(&CAN_FilterInitStructure);//滤波器初始化
CAN_ITConfig(CAN2,CAN_IT_FMP0,ENABLE);//FIFO0消息挂号中断允许.
NVIC_InitStructure.NVIC_IRQChannel = CAN2_RX0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; // 主优先级为1
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2; // 次优先级为1
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
return 0;
}
void CAN1_RX0_IRQHandler(void)
{
CAN_Receive(CAN1, CAN_Filter_FIFO0, &CAN1_RxMessage);
CAN_Flag = 1;
}
void CAN1_RX1_IRQHandler(void)
{
CAN_Receive(CAN1, CAN_Filter_FIFO1, &CAN1_RxMessage);
CAN_FIFO1_Flag = 1;
}
void CAN2_RX0_IRQHandler(void)
{
CAN_Receive(CAN2, CAN_Filter_FIFO0, &CAN2_RxMessage);
CAN2_Flag = 1;
}
u8 CAN1_Send_Msg(int extid,u8* msg,u8 len)
{
u8 mbox;
u16 i = 0;
CanTxMsg TxMessage;
TxMessage.StdId = 0x12; // 标准标识符（12位）
TxMessage.ExtId = extid; // 设置扩展标示符（29位）
TxMessage.IDE = 4; // 使用1为扩展标识符、0为标准标识符
TxMessage.RTR = 0; // 消息类型为数据帧，0为数据帧、1为远程帧
TxMessage.DLC = len; // 发送帧字节数
for(i = 0;i < len;i++)
TxMessage.Data[i] = msg[i]; // 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;
}
u8 CAN2_Send_Msg(u8* msg,u8 len)
{
u8 mbox;
u16 i=0;
CanTxMsg TxMessage;
TxMessage.StdId=0x12; // 标准标识符（12位）
TxMessage.ExtId=0x0005ffff; // 设置扩展标示符（29位）
TxMessage.IDE=4; // 使用1为扩展标识符、0为标准标识符
TxMessage.RTR=0; // 消息类型为数据帧，0为数据帧、1为远程帧
TxMessage.DLC=len; // 发送帧字节数
for(i=0;i=0XFFF)return 1;
return 0;
}
CAN1_Mode_Init(CAN_SJW_1tq,CAN_BS2_6tq,CAN_BS1_7tq,12,CAN_Mode_Normal);//bsp = APB1_CLK / BRP / (1 + BS2 + BS1) 250kbps
进行初始化
直接看代码中配置滤波器段，首先选择滤波器编号（个人理解在32位标识符屏蔽位模式下CAN1对应滤波器组0 ~13 ，CAN2对应滤波器组14 ~ 27），选择好过滤器后，接着就是设置两个屏蔽寄存器，之后是关键，要把这个滤波器编号对应到FIFO上，只有这样对应FIFO中才能有数据。
代码中写了两个滤波器，分别对应FIFO0和FIFO1，STM32的can在进行筛选时根据滤波器编号从0到13，所以在设置两个滤波器的情况下，第二个要筛选的数对应位数要比第一个少。如，上述代码我要ID=00 00 00 FF的数据单独进入一个中断，那么我就必须使用编号低的滤波器组。