STM32 自定义UART数据格式（串口通信点亮LED实验）

起始位：0xaa告诉机器我们要开始传输数据了。

校验位：等于前几项数据位的相加。

结束位：结束传输。 

自定义UART数据格式：

1》CPU与CPU之间

2》外设与CPU之间

这里举例，利用串口调试助手发送一串数据，来控制4个LED灯。

数据格式

例如

LED1点亮：aa 01 01 02 ff

LED2熄灭：aa 02 00 02 ff

1. 先对串口中断和UART进行配置

   void Uart1_Configuration(void)
   {
   	GPIO_InitTypeDef GPIO_InitStructure;
   	USART_InitTypeDef USART_InitStructure;
   	
   	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);
   	
   	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;   //TX
   	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
   	GPIO_Init(GPIOA, &GPIO_InitStructure);
   	
   	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;   //TX
   	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
   	GPIO_Init(GPIOA, &GPIO_InitStructure);
   	
   	USART_InitStructure.USART_BaudRate = 115200;
   	USART_InitStructure.USART_WordLength = USART_WordLength_8b;
   	USART_InitStructure.USART_StopBits = USART_StopBits_1;
   	USART_InitStructure.USART_Parity = USART_Parity_No;
   	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
   	USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
   	USART_Init(USART1, &USART_InitStructure);
   	USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
   	USART_Cmd(USART1, ENABLE);
   }
   
   void Uart1_NVIC_Init(void)
   {
   	NVIC_InitTypeDef NVIC_InitStructure;
   	
   	NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);	
   	NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
   	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
   	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
   	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
   	NVIC_Init(&NVIC_InitStructure);
   }

2. LED配置

   void Led_Configuration(void)
   {
   	GPIO_InitTypeDef GPIO_InitStructure;
   
   	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
   	
   	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 | GPIO_Pin_4;
   	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
   	GPIO_Init(GPIOA, &GPIO_InitStructure);
   }

3.  UART中断

   void control_LED(unsigned int led_number, unsigned int status)
   {
   	GPIO_WriteBit(GPIOA, (uint16_t)1<<led_number, (BitAction)status);
   }
   void USART1_IRQHandler(void)
   {
   	static unsigned int i = 1;
   	static unsigned int flag = 0;
   	
   	static unsigned int arr[5] = {0, 0, 0, 0, 0};
   	
   	unsigned char ch;
   	while(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == SET)
   	{
   		ch = USART_ReceiveData(USART1);
   		if(ch == 0xaa)
   		{
   			arr[0] = ch;
   			flag = 1;
   		}
   		if(ch != 0xaa && flag == 1)
   		{
   			arr[i++] = ch;
   			
   			if(i == 5)
   			{
   				flag = 0;
   				i = 1;
   				if(((arr[i]+arr[2]) == arr[3]) && arr[4] == 0xff)
   					control_LED(arr[1], arr[2]);
   			}
   		}
   	}			
   }

           static unsigned int arr[5] = {0, 0, 0, 0, 0};如果直接定义arr，这样每次进中断arr都会被初始化为0，所以我们必须在arr的定义类型前加static，把它变为全局变量。这样arr只会在第一次的时候初始化，随后每次进中断时arr都不会被重新赋值了。

                同理这里定义flag，用来判断，是否开始传输，是则为1，否则为0。

本实验接线：TTL：RX》A10，TX》A9，5V》5V，GND》GND，4个LED灯接在A1，A2，A3，A4，