STM32F429 422串口通信

1.422串口的硬件原理图如下：

2.422串口和232串口不同的是引脚的电平控制，还有DE是发送使能，置高即可：RE是接收使能，置低即可。422接出来的是4根线，有RS485_A、RS485_B、RS485_Z、RS485_Y，对应422串口线的DB1、DB2、DB3、DB4,，DB5连接地线，其他的配置用232串口的代码即可。

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3.GPIO的配置：

1. void RS422_Config()
   
2. {
   
3. GPIO_InitTypeDef GPIO_InitStructure;
   
4. USART_InitTypeDef USART_InitStructure;
   
5. /* PC6/USART6_TX , PC7/USART6_RX, PG12/USART6_RTS, PG13/USART6_CTS */
   
6. 
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7. RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC |RCC_AHB1Periph_GPIOG, ENABLE);
   
8. 
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9. GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
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10. GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
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11. GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    
12. GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
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13. GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13;
    
14. GPIO_Init(GPIOG, &GPIO_InitStructure);
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15. 
    
16. GPIO_ResetBits(GPIOG,GPIO_Pin_12); //USART6_RTS
    
17. GPIO_SetBits(GPIOG,GPIO_Pin_13); //USART6_CTS
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18. 
    
19. RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART6, ENABLE);
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20. 
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21. GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_USART6);
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22. 
    
23. GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_USART6);
    
24. 
    
25. GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    
26. GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
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27. GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
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28. 
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29. GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
    
30. GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    
31. GPIO_Init(GPIOC, &GPIO_InitStructure);
    
32. 
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33. GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    
34. GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
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35. GPIO_Init(GPIOC, &GPIO_InitStructure);
    
36. 
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37. USART422_NVIC_Config();
    
38. 
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39. USART_InitStructure.USART_BaudRate = 115200;
    
40. USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    
41. USART_InitStructure.USART_StopBits = USART_StopBits_1;
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42. USART_InitStructure.USART_Parity = USART_Parity_No ;
    
43. //USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_RTS_CTS;
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44. USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
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45. USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
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46. USART_Init(USART6, &USART_InitStructure);
    
47. 
    
48. USART_ITConfig(USART6, USART_IT_RXNE, ENABLE);
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49. 
    
50. USART_Cmd(USART6, ENABLE);
    
51. 
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52. USART_ClearFlag(USART6, USART_FLAG_TC);
    
53. }
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4.422串口中断的配置：

1. void USART422_NVIC_Config(void)
   
2. {
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3. NVIC_InitTypeDef NVIC_InitStructure;
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4. NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //设置中断分组2
   
5. 
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6. NVIC_InitStructure.NVIC_IRQChannel = USART6_IRQn; // 选择 USART6 通道
   
7. NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; //抢占优先级设置为3
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8. NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; //响应优先级设置为1
   
9. NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //开启中断
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10. NVIC_Init(&NVIC_InitStructure); //初始化配置
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11. }
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12. 
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13. void USART6_IRQHandler (void)
    
14. {
    
15. char Date422 = 0;

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5.主函数的发送：

1. int main(void)
   
2. {
   
3. 
   
4. Delay_Init(); //延时函数初始化
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5. RS422_Config(); //422串口初始化
   
6. while(1)
   
7. {
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8. Delay_ms(1000);
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9. USART_SendData(USART6,3); //将接收到的数据发回
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10. }
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11. }

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