有个项目需要用到STM32F072的4个串口，串口1和2都已经OK，串口3和4怎么配置都配置不成功，发送数据都没有出来。配置串口1和2的时候，仿真读串口1和2的寄存器地址能看到设置进去的数据，但是3和4就没有，都是0。
有用过的帮忙看一下是什么情况，谢谢。
配置代码如下：

1. void USART3_Config(void)
   
2. {
   
3.     USART_InitTypeDef USART_InitStructure;
   
4. //    NVIC_InitTypeDef NVIC_InitStructure;
   
5.     GPIO_InitTypeDef GPIO_InitStructure;
   
6. 
   
7.     USART_DeInit(USART4);
   
8. 
   
9.     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC, ENABLE);
   
10.     RCC_APB2PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
    
11.    
    
12.     /* Connect PXx to USARTx_Tx */
    
13.     GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_1);
    
14.     /* Connect PXx to USARTx_Rx */
    
15.     GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_1);
    
16. 
    
17.     /* Configure USART Tx and Rx as alternate function push-pull */
    
18.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    
19.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_Level_3;
    
20.     GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    
21.     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    
22.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    
23.     GPIO_Init(GPIOC, &GPIO_InitStructure);
    
24. 
    
25.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
    
26.     GPIO_Init(GPIOC, &GPIO_InitStructure);
    
27. 
    
28.     USART_InitStructure.USART_BaudRate = 115200;
    
29.     USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    
30.     USART_InitStructure.USART_StopBits = USART_StopBits_1;
    
31.     USART_InitStructure.USART_Parity = USART_Parity_No;
    
32.     USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    
33.     USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    
34.     USART_Init(USART3, &USART_InitStructure);
    
35. 
    
36. //    USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);  
    
37. 
    
38.     /* NVIC configuration */
    
39.     /* Enable the USARTx Interrupt */
    
40. //    NVIC_InitStructure.NVIC_IRQChannel = USART3_4_IRQn;
    
41. //    NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
    
42. //    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    
43. //    NVIC_Init(&NVIC_InitStructure);
    
44. 
    
45.     /* Enable USART */
    
46.     USART_Cmd(USART3, ENABLE);
    
47. }

复制代码

1. void USART4_Config(void)
   
2. {
   
3.     USART_InitTypeDef USART_InitStructure;
   
4. //    NVIC_InitTypeDef NVIC_InitStructure;
   
5.     GPIO_InitTypeDef GPIO_InitStructure;
   
6. 
   
7. //    USART_DeInit(USART4);
   
8. 
   
9.     RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
   
10.     RCC_APB2PeriphClockCmd(RCC_APB1Periph_USART4, ENABLE);
    
11.    
    
12.     /* Connect PXx to USARTx_Tx */
    
13.     GPIO_PinAFConfig(GPIOA, GPIO_PinSource0, GPIO_AF_4);
    
14.     /* Connect PXx to USARTx_Rx */
    
15.     GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_4);
    
16. 
    
17.     /* Configure USART Tx and Rx as alternate function push-pull */
    
18.     GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    
19.     GPIO_InitStructure.GPIO_Speed = GPIO_Speed_Level_3;
    
20.     GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    
21.     GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    
22.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    
23.     GPIO_Init(GPIOA, &GPIO_InitStructure);
    
24. 
    
25.     GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
    
26.     GPIO_Init(GPIOA, &GPIO_InitStructure);
    
27. 
    
28.     USART_InitStructure.USART_BaudRate = 115200;
    
29.     USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    
30.     USART_InitStructure.USART_StopBits = USART_StopBits_1;
    
31.     USART_InitStructure.USART_Parity = USART_Parity_No;
    
32.     USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    
33.     USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    
34.     USART_Init(USART4, &USART_InitStructure);
    
35. 
    
36.     USART_ITConfig(USART4, USART_IT_RXNE, ENABLE);  
    
37. 
    
38.     /* NVIC configuration */
    
39.     /* Enable the USARTx Interrupt */
    
40. //    NVIC_InitStructure.NVIC_IRQChannel = USART3_4_IRQn;
    
41. //    NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
    
42. //    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    
43. //    NVIC_Init(&NVIC_InitStructure);
    
44. 
    
45.     /* Enable USART */
    
46.     USART_Cmd(USART4, ENABLE);
    
47. }

复制代码
发送数据如下，循环里连续发送0XAA。
        while(1)
        {
        USART_SendData(USART4,0xAA);
        while (USART_GetFlagStatus(USART4, USART_FLAG_TC) == RESET);
        
        USART_SendData(USART3,0xAA);
        while (USART_GetFlagStatus(USART3, USART_FLAG_TC) == RESET);  
        }