32F042F6的CAN总线配置问题，回环测试有数据，正常模式没数据

1hexie 提问时间：2019-4-24 14:25 /

问答
是否解决:

大家好，我用的是STM32F042F6，TSSOP20芯片，CAN引脚为PA11，PA12（与PA9，PA10复用）
当设置为CAN_Mode_LoopBack时，可以在用示波器在TX引脚看到波形，并且程序里可以接收到数据；
当设置为CAN_Mode_Normal时，TX引脚看不到波形，并且也不能接受发送CAN数据。
代码如下，请大家帮忙看看，谢谢！！

void CAN1_Init(u16 Baudrate,u16 Receive_MsgId)
{
GPIO_InitTypeDef    GPIO_InitStructure;
NVIC_InitTypeDef    NVIC_InitStructure;
CAN_InitTypeDef       CAN_InitStructure;
CAN_FilterInitTypeDef  CAN_FilterInitStructure;

      /* CAN1 Periph clock enable */
      RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN, ENABLE);
      RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA , ENABLE);

      RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
      SYSCFG->CFGR1 |= (uint32_t)SYSCFG_CFGR1_PA11_PA12_RMP;

      GPIO_PinAFConfig(GPIOA, GPIO_PinSource11, GPIO_AF_4);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource12, GPIO_AF_4);

/* Configure CAN pin: RX */  // PA11
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
      GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
//       GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
      GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Configure CAN pin: TX */ // PA12
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;
GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_AF;
            GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
            GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
//       GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* enabling interrupt */
NVIC_InitStructure.NVIC_IRQChannel       = CEC_CAN_IRQn;;
NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd    = ENABLE;
NVIC_Init(&NVIC_InitStructure);

//CAN_INIT();//CA???N??
/* CAN register init */
// CAN_DeInit(CAN);
// CAN_StructInit(&CAN_InitStructure);

/* CAN cell init */
CAN_InitStructure.CAN_TTCM = DISABLE;
CAN_InitStructure.CAN_ABOM = DISABLE;
CAN_InitStructure.CAN_AWUM = DISABLE;
CAN_InitStructure.CAN_NART = DISABLE;
CAN_InitStructure.CAN_RFLM = DISABLE;
CAN_InitStructure.CAN_TXFP = DISABLE;
CAN_InitStructure.CAN_Mode = CAN_Mode_Normal;//CAN_Mode_LoopBack; //
CAN_InitStructure.CAN_SJW  = CAN_SJW_1tq;
CAN_InitStructure.CAN_BS1  = CAN_BS1_4tq;
CAN_InitStructure.CAN_BS2  = CAN_BS2_3tq;

            CAN_InitStructure.CAN_Prescaler=6;

CAN_Init(CAN,&CAN_InitStructure);

CAN_FilterInitStructure.CAN_FilterNumber = 1;
CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdList;
CAN_FilterInitStructure.CAN_FilterScale  = CAN_FilterScale_32bit;

CAN_FilterInitStructure.CAN_FilterIdHigh= (((u32)Receive_MsgId<<21)&0xFFFF0000)>>16;
// CAN_FilterInitStructure.CAN_FilterIdHigh=0X00;                //????ID??
CAN_FilterInitStructure.CAN_FilterIdLow= (((u32)Receive_MsgId<<21)|CAN_ID_STD|CAN_RTR_DATA)&0xFFFF; //????ID??

CAN_FilterInitStructure.CAN_FilterMaskIdHigh    = 0xFFFF;
CAN_FilterInitStructure.CAN_FilterMaskIdLow    = 0xFFFF;
CAN_FilterInitStructure.CAN_FilterFIFOAssignment = CAN_FIFO0;
CAN_FilterInitStructure.CAN_FilterActivation    = ENABLE;
CAN_FilterInit(&CAN_FilterInitStructure);

/* CAN FIFO0 message pending interrupt enable */
CAN_ITConfig(CAN,CAN_IT_FMP0, ENABLE);

}

赞收藏评论4 发布时间：2019-4-24 14:25

4个回答

wh8 回答时间：2019-4-24 16:29:33

正常模式下，CAN是带纠错的，需要你两端的设备都正常连接才行。
否则你对面设备没接，单片机CAN外设就认为通信出错了，也就不会再正常发送了。
所以你把另一边的CAN设备接上再测测。
参考http://community.st.com/s/questi ... /can-loopbacknormal
另外环回模式就是用来测代码的，环回下没问题，代码配置一般就不会有问题