STM407CAN回环模式能收到数据，但Tx管脚无波形

只看该作者 · 2015-8-3 17:14

手册上说，Tx管脚能检测到波形，但是测时没有，大神提示下大概是哪些问题导致的？

只看该作者 · 2015-8-3 17:19

   RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);

   GPIO_PinAFConfig(GPIOB,GPIO_PinSource9,GPIO_AF_CAN1);
   GPIO_PinAFConfig(GPIOB,GPIO_PinSource8,GPIO_AF_CAN1);

   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9| GPIO_Pin_8;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
// GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;//100MHz
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOB, &GPIO_InitStructure);

有人说是IO配置可能有问题，

3万 · 2015-8-3 20:14

void CAN_Config(void)
{
  GPIO_InitTypeDef  GPIO_InitStructure;

  //CAN GPIOs configuration **************************************************
  // Connect CAN pins to AF9
  GPIO_PinAFConfig(CAN_GPIO_RX_PORT, CAN_RX_SOURCE, CAN_AF_PORT);
  GPIO_PinAFConfig(CAN_GPIO_TX_PORT, CAN_TX_SOURCE, CAN_AF_PORT);

  // Configure CAN RX and TX pins
  GPIO_InitStructure.GPIO_Pin =  CAN_TX_PIN;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
  GPIO_Init(CAN_GPIO_TX_PORT, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = CAN_RX_PIN ;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_UP;
  GPIO_Init(CAN_GPIO_RX_PORT, &GPIO_InitStructure);

  // CAN configuration ********************************************************
  // Enable CAN clock
  RCC_APB1PeriphClockCmd(CAN_CLK, ENABLE);

  // CAN register init
  CAN_DeInit(CANx);

  // 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_InitStructure.CAN_SJW = CAN_SJW_1tq;

  // CAN Baudrate = 1 MBps (CAN clocked at 30 MHz)
//BaudRate = PCLK1/((BS1 + BS2 + 1)*Prescaler)=(168/4)/((5+8+1)*3)=1M
  CAN_InitStructure.CAN_BS1 = CAN_BS1_5tq;
  CAN_InitStructure.CAN_BS2 = CAN_BS2_8tq;
  CAN_InitStructure.CAN_Prescaler = 3;
  CAN_Init(CANx, &CAN_InitStructure);

  CAN_FilterInitStructure.CAN_FilterNumber = 0;

  CAN_FilterInitStructure.CAN_FilterMode = CAN_FilterMode_IdMask;
  CAN_FilterInitStructure.CAN_FilterScale = CAN_FilterScale_32bit;
  CAN_FilterInitStructure.CAN_FilterIdHigh = 0x0000;
  CAN_FilterInitStructure.CAN_FilterIdLow = 0x0000;
  CAN_FilterInitStructure.CAN_FilterMaskIdHigh = 0x0000;
  CAN_FilterInitStructure.CAN_FilterMaskIdLow = 0x0000;
  CAN_FilterInitStructure.CAN_FilterFIFOAssignment = 0;
  CAN_FilterInitStructure.CAN_FilterActivation = ENABLE;
  CAN_FilterInit(&CAN_FilterInitStructure);

  // Transmit Structure preparation
  TxMessage.StdId = 0x321;
  TxMessage.ExtId = 0x01;
  TxMessage.RTR = CAN_RTR_DATA;
  TxMessage.IDE = CAN_ID_STD;
  TxMessage.DLC = 8;

  // Enable FIFO 0 message pending Interrupt
  CAN_ITConfig(CANx, CAN_IT_FMP0, ENABLE);
}