各位，小弟刚刚开始学习STM32，现在正在调试STM103VBT6上的CAN接口，我把ST的库中的CAN例子放在自己的板子上验证了一下，测试通过。我自己的板子上使用的CAN端口被映射到D0,D1上了，我把CAN通信模式从Loopback模式修改成normal，用示波器在CANRX（PD0,已经与CAN收发器断开了）和CANTX（PD1,已经与CAN收发器断开了）引脚上查看了，结果CANTX引脚电平为0，CANRX引脚为3.3V，CAN通信模式换成原来的Loopback模式，在CANTX引脚上仍然看不到任何东西，请大家帮忙分析一下我的问题出来哪里了。
下面时我的代码
int main(void)
{
#ifdef DEBUG
debug();
#endif
/* System Clocks Configuration */
RCC_Configuration();
/* NVIC Configuration */
NVIC_Configuration();
/* GPIO ports pins Configuration */
GPIO_Configuration();
while (1)
{
/* CAN transmit at 100Kb/s and receive by polling in loopback mode */
TestRx = CAN_Polling();
if (TestRx == FAILED)
{
/* Turn on led */
GPIO_SetBits(GPIOE, GPIO_Pin_2);
}
else
{
/* Turn on led */
GPIO_SetBits(GPIOE, GPIO_Pin_3);
}
}
}
/*******************************************************************************
* Function Name : RCC_Configuration
* Description : Configures the different system clocks.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void RCC_Configuration(void)
{
/* RCC system reset(for debug purpose) */
RCC_DeInit();
/* Enable HSE */
RCC_HSEConfig(RCC_HSE_ON);
/* Wait till HSE is ready */
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if(HSEStartUpStatus == SUCCESS)
{
/* Enable Prefetch Buffer */
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
/* Flash 2 wait state */
FLASH_SetLatency(FLASH_Latency_2);
/* HCLK = SYSCLK */
RCC_HCLKConfig(RCC_SYSCLK_Div1);
/* PCLK2 = HCLK */
RCC_PCLK2Config(RCC_HCLK_Div1);
/* PCLK1 = HCLK/2 */
RCC_PCLK1Config(RCC_HCLK_Div2);
/* PLLCLK = 8MHz * 9 = 72 MHz */
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
/* Enable PLL */
RCC_PLLCmd(ENABLE);
/* Wait till PLL is ready */
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
{
}
/* Select PLL as system clock source */
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
/* Wait till PLL is used as system clock source */
while(RCC_GetSYSCLKSource() != 0x08)
{
}
}
/* CAN Periph clock enable */
// Enable GPIOD clock
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE); // 必要么
}
/*******************************************************************************
* Function Name : GPIO_Configuration
* Description : Configures the different GPIO ports.
* Input : None
* Output : None
* Return : None
*******************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
// Configure LED pin PE.02 -- PE.03 as Output push-pull
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOE, &GPIO_InitStructure);
// Configure CAN pin: RX
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
GPIO_Init(GPIOD, &GPIO_InitStructure);
// Configure CAN pin: TX
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
// CAN pin remap to PD0/PD1
GPIO_PinRemapConfig(GPIO_Remap2_CAN,ENABLE);
}
/*******************************************************************************
* Function Name : CAN_Polling
* Description : Configures the CAN, transmit and receive by polling
* Input : None
* Output : None
* Return : PASSED if the reception is well done, FAILED in other case
*******************************************************************************/
TestStatus CAN_Polling(void)
{
CAN_InitTypeDef CAN_InitStructure;
CAN_FilterInitTypeDef CAN_FilterInitStructure;
CanTxMsg TxMessage;
CanRxMsg RxMessage;
u32 i = 0;
u8 TransmitMailbox = 0;
/* CAN register init */
CAN_DeInit();
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_LoopBack;
CAN_InitStructure.CAN_Mode=CAN_Mode_Normal;
CAN_InitStructure.CAN_SJW=CAN_SJW_1tq;
CAN_InitStructure.CAN_BS1=CAN_BS1_8tq;
CAN_InitStructure.CAN_BS2=CAN_BS2_7tq;
CAN_InitStructure.CAN_Prescaler=5;
CAN_Init(&CAN_InitStructure);
/* CAN filter init */
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 */
TxMessage.StdId=0x11;
TxMessage.RTR=CAN_RTR_DATA;
TxMessage.IDE=CAN_ID_STD;
TxMessage.DLC=2;
TxMessage.Data[0]=0xCA;
TxMessage.Data[1]=0xFE;
TransmitMailbox=CAN_Transmit(&TxMessage);
i = 0;
while((CAN_TransmitStatus(TransmitMailbox) != CANTXOK) && (i != 0xFF))
{
i++;
}
i = 0;
while((CAN_MessagePending(CAN_FIFO0) < 1) && (i != 0xFF))
{
i++;
}
/* receive */
RxMessage.StdId=0x00;
RxMessage.IDE=CAN_ID_STD;
RxMessage.DLC=0;
RxMessage.Data[0]=0x00;
RxMessage.Data[1]=0x00;
CAN_Receive(CAN_FIFO0, &RxMessage);
if (RxMessage.StdId!=0x11)
{
return FAILED;
}
if (RxMessage.IDE!=CAN_ID_STD)
{
return FAILED;
}
if (RxMessage.DLC!=2)
{
return FAILED;
}
if ((RxMessage.Data[0]<<8|RxMessage.Data[1])!=0xCAFE)
{
return FAILED;
}
return PASSED; /* Test Passed */
}
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