根据stm32的can总线完全研讨

/* CAN cell init */
CAN_InitStructure.CAN_TTCM=DISABLE;//制止时刻触发通讯方式
CAN_InitStructure.CAN_ABOM=DISABLE;
CAN_InitStructure.CAN_AWUM=DISABLE;
CAN_InitStructure.CAN_NART=DISABLE;//CAN报文只被发送1次，不论发送的成果怎么（成功、犯错或裁定丢掉）
CAN_InitStructure.CAN_RFLM=DISABLE;
CAN_InitStructure.CAN_TXFP=DISABLE;
CAN_InitStructure.CAN_Mode=CAN_Mode_Normal;
//CAN_Mode_LoopBack
//CAN_Mode_Normal
CAN_InitStructure.CAN_SJW=CAN_SJW_1tq;
CAN_InitStructure.CAN_BS1=CAN_BS1_5tq;//1–16
CAN_InitStructure.CAN_BS2=CAN_BS2_2tq;//1–8
CAN_InitStructure.CAN_Prescaler=2;
CAN_Init(&CAN_InitStructure);
#ifdef can_id_filter
/* CAN filter init */
CAN_FilterInitStructure.CAN_FilterNumber=0;//挑选过滤器0
CAN_FilterInitStructure.CAN_FilterMode=CAN_FilterMode_IdMask;//指定过滤器被设置为标识符屏蔽方式
CAN_FilterInitStructure.CAN_FilterScale=CAN_FilterScale_32bit;//给出过滤器位宽为32位
CAN_FilterInitStructure.CAN_FilterIdHigh=slave_id<<5;//过滤器标识符
CAN_FilterInitStructure.CAN_FilterIdLow=0x0000;//
CAN_FilterInitStructure.CAN_FilterMaskIdHigh=0xffff;//过滤器屏蔽标识符
CAN_FilterInitStructure.CAN_FilterMaskIdLow=0xfffc;
CAN_FilterInitStructure.CAN_FilterFIFOAssignment=0;//挑选FIFO0
CAN_FilterInitStructure.CAN_FilterActivation=ENABLE;//使能过滤器
CAN_FilterInit(&CAN_FilterInitStructure);//进入初始化函数
#else
/* CAN filter init */
CAN_FilterInitStructure.CAN_FilterNumber=0;//挑选过滤器0
CAN_FilterInitStructure.CAN_FilterMode=CAN_FilterMode_IdMask;//指定过滤器被设置为标识符屏蔽方式
CAN_FilterInitStructure.CAN_FilterScale=CAN_FilterScale_32bit;//给出过滤器位宽为32位
CAN_FilterInitStructure.CAN_FilterIdHigh=0x0000;//过滤器标识符
CAN_FilterInitStructure.CAN_FilterIdLow=0x0000;//
CAN_FilterInitStructure.CAN_FilterMaskIdHigh=0x0000;//过滤器屏蔽标识符
CAN_FilterInitStructure.CAN_FilterMaskIdLow=0x0000;
CAN_ITConfig(CAN_IT_FMP0, ENABLE);//使能指定的can中止
}

对扩展数据帧过滤：

CAN_FilterInitStructure.CAN_FilterNumber=0;
CAN_FilterInitStructure.CAN_FilterMode=CAN_FilterMode_IdMask;
CAN_FilterInitStructure.CAN_FilterScale=CAN_FilterScale_32bit;
CAN_FilterInitStructure.CAN_FilterIdHigh=(((u32)CAN_ID<<3)&0xFFFF0000)>>16;
CAN_FilterInitStructure.CAN_FilterIdLow=(((u32)CAN_ID<<3)|CAN_ID_EXT|CAN_RTR_DATA)&0xFFFF;
CAN_FilterInitStructure.CAN_FilterMaskIdHigh=0xFFFF;
CAN_FilterInitStructure.CAN_FilterMaskIdLow=0xFFFF;

对规范数据帧过滤：

CAN_FilterInitStructure.CAN_FilterIdHigh=(((u32)CAN_ID0<<21)&0xFFFF0000)>>16;
CAN_FilterInitStructure.CAN_FilterIdLow=(((u32)CAN_ID0<<21)|CAN_ID_STD|CAN_RTR_DATA)&0xFFFF;
CAN_FilterInitStructure.CAN_FilterMaskIdHigh=0xFFFF;
CAN_FilterInitStructure.CAN_FilterMaskIdLow=0xFFFF;

假设要对规范长途帧进行过滤,那么：

只需要将

CAN_FilterInitStructure.CAN_FilterIdLow=(((u32)CAN_ID0<<21)|CAN_ID_STD|CAN_RTR_DATA)&0xFFFF;改成：

CAN_FilterInitStructure.CAN_FilterIdLow=(((u32)CAN_ID0<<21)|CAN_ID_STD|CAN_RTR_REMOTE)&0xFFFF;

5、can总线的帧格局

数据帧格局：

长途帧格局：

6、can总线的逻辑电平

can总线的物理衔接有两根线：CANH和CANL，以差分的方式输出。

（有的时分有地线，作为屏蔽线运用）

can总线的高电平3.5v，表明逻辑0

can总线的低电平1.5v，表明逻辑1

7、CAN总线的波特率核算

can时钟是RCC_APB1PeriphClock，要注意CAN时钟频率
CAN波特率=RCC_APB1PeriphClock/CAN_SJW CAN_BS1 CAN_BS2/CAN_Prescaler;
假如CAN时钟为8M，CAN_SJW=1，CAN_BS1=8，CAN_BS2=7，CAN_Prescaler=2
那么波特率便是=8M/(1 8 7)/2=250K

8、can总线的裁定机制

依据裁定来判别优先级：

(1)若在同一时刻，规范格局的报文与扩展格局的报文一起抢占总线，且它们的根底ID相同，则发规范格局的报文节点就会PK成功。这是由于扩展格局在根本ID后，紧接着是SRR位，与IDE位，且这两位都是隐性位。而在规范格局中，这两位别离对应的位为RTR与r1，其间RTR既可认为隐性位，也可认为显性位，，可是r1有必要为显性位。由裁定规矩能够此刻规范帧必定胜出。

(2)同理，假如在同一时刻，具有相同格局，且具有相同ID的数据帧与长途帧抢夺总线操控权，那么数据帧必定胜出。由于RTR显性表明数据帧，隐性表明长途帧。