[STM32 learning] (7) use of serial port 2 (usart2)

SCM serial port must be learned , And it's important , It is very important in data transmission and program debugging .

Learn more about this blog USART2 A serial port

In fact, not every serial port IO Can be used as serial port , He is fixed IO Oral .

Such as USART1 Serial port corresponding to IO yes PA9、PA10, This is very important , Don't get it wrong . The material document is shown in the figure below ：

STM32 General steps of serial port configuration ( Library function )
           (1) Serial clock enable ：RCC_APBxPeriphClockCmd();
                       GPIO Clock enable ：RCC_AHBxPeriphClockCmd();

           (2) Pin multiplexing mapping ：GPIO_PinAFConfig();
           (3)GPIO Port mode configuration ：GPIO_Init(); The mode is configured to GPIO_Mode_AF
           (4) Initialization of serial port parameters ：USART_Init();
           (5) Turn on interrupt and initialize NVIC（ If you need to turn on interrupt, you need this step ）
                 NVIC_Init();
                 USART_ITConfig();
           (6) Enable serial port ：USART_Cmd();
           (7) Write interrupt handling functions ：USARTx_IRQHandler();
           (8) Serial data transmission ：
                  void USART_SendData();// Send data to serial port ,DR
                  uint16_t USART_ReceiveData();// receive data , from DR Read the received data
          (9) Serial port transmission state acquisition ：
                  FlagStatus USART_GetFlagStatus();
                  void USART_ClearITPendingBit();

The model of single chip microcomputer I use here is STM32F103VET

The code is as follows ：
main.c

#include "led.h"
#include "delay.h"
#include "key.h"
#include "sys.h"
#include "usart.h"

int main(void)
{		
	u8 t;
	u8 len;	
	u16 times=0;
	delay_init();	    	 // Delay function initialization 	  
	NVIC_Configuration(); 	 // Set up NVIC Interrupt grouping 2:2 Bit preemption priority ,2 Bit response priority 
	uart2_init(9600);	 // The serial port is initialized to 9600
	 
	LED_Init();			     //LED Port initialization 
	KEY_Init();          // Initialize the hardware interface connected with the key 
	while(1)
	{
		if(USART_RX_STA&0x8000)
		{					   
			len=USART_RX_STA&0x3fff;// The length of data received this time 
			printf(" The message you sent is :\r\n");
			for(t=0;t<len;t++)
			{
				USART_SendData(USART2, USART_RX_BUF[t]);// Serial port 2 send data 
 				while(USART_GetFlagStatus(USART2,USART_FLAG_TC)!=SET);// Wait for the end of sending 
			}
			printf("\r\n");// Insert newline 
			USART_RX_STA=0;
		}
		else
		{
			times++;
			if(times%5000==0)
			{
				printf("\r\n Serial port experiment \r\n");
				printf("wantin\r\n\r\n");
			}
			if(times%200==0)printf(" Please input data , End with enter \n");  
			if(times%30==0)LED0=!LED0;// flashing LED, Indicates that the system is running .
			delay_ms(10);   
		}
	}	 
}

usart.h

#ifndef __USART_H
#define __USART_H
#include "stdio.h"	
#include "sys.h" 
//	 
// 	
#define USART_REC_LEN  			200  	// Define the maximum number of bytes received  200
#define EN_USART1_RX 			1		// Can make （1）/ prohibit （0） A serial port 1 receive 
	  	
extern u8  USART_RX_BUF[USART_REC_LEN]; // Receive buffer , Maximum USART_REC_LEN Bytes . The last byte is a newline character  
extern u16 USART_RX_STA;         		// Receive status flag 	
// If you want to interrupt the receiving serial port , Please do not comment on the following macro definition 

void uart2_init(u32 bound);

#endif

usart.c

#include "sys.h"
#include "usart.h"	  

//	 
// 	  
 

//
// Add the following code , Support printf function , You don't need to choose use MicroLIB	  
#if 1
#pragma import(__use_no_semihosting)             
// Support functions required by the standard library                  
struct __FILE 
{ 
	int handle; 

}; 

FILE __stdout;       
// Definition _sys_exit() To avoid using semi host mode     
void _sys_exit(int x) 
{ 
	x = x; 
} 
// redefinition fputc function  
int fputc(int ch, FILE *f)
{      
 	while(USART_GetFlagStatus(USART2,USART_FLAG_TC)==RESET); 
	USART_SendData(USART2,(uint8_t)ch);   
	
	return ch;
}
#endif 

/* Use microLib Methods */
 /* 
int fputc(int ch, FILE *f)
{
	USART_SendData(USART1, (uint8_t) ch);

	while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET) {}	
   
    return ch;
}
int GetKey (void)  { 

    while (!(USART1->SR & USART_FLAG_RXNE));

    return ((int)(USART1->DR & 0x1FF));
}
*/
 
#if EN_USART1_RX   // If enabled, receive 
// A serial port 1 Interrupt service routine 
// Be careful , Read USARTx->SR Can avoid inexplicable mistakes    	
u8 USART_RX_BUF[USART_REC_LEN];     // Receive buffer , Maximum USART_REC_LEN Bytes .
// Reception status 
//bit15,	 Receive completion flag 
//bit14,	 Received 0x0d
//bit13~0,	 Number of valid bytes received 
u16 USART_RX_STA=0;       // Receive status flag 	  

void uart2_init(u32 bound){
	 //GPIO Port settings 
	GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	 
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2,ENABLE);	// Can make USART2 The clock 
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);	// Can make GPIOA The clock 
	USART_DeInit(USART2);  // Reset serial port 2
	 //USART2_TX   PA.2
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2; //PA.2
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;	// Multiplexing push pull output 
	GPIO_Init(GPIOA, &GPIO_InitStructure); // initialization PA2

	 //USART2_RX	  PA.3
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;// Floating input 
	GPIO_Init(GPIOA, &GPIO_InitStructure);  // initialization PA3


	//USART  Initialize settings 

	USART_InitStructure.USART_BaudRate = bound;// Generally set as 9600;
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;// The word is 8 Bit data format 
	USART_InitStructure.USART_StopBits = USART_StopBits_1;// A stop bit 
	USART_InitStructure.USART_Parity = USART_Parity_No;// No parity bit 
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;// No hardware data flow control 
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;	// Transceiver mode 

	 USART_Init(USART2, &USART_InitStructure); // Initialize serial port 
	#if EN_USART1_RX		  // If enabled, receive   
	//Usart1 NVIC  To configure 
	NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;// preemption 3
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;		// Sub priority 3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQ Channel enable 
	NVIC_Init(&NVIC_InitStructure);	// Initialize... According to the specified parameters VIC register 

	USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);// Open interrupt 
	#endif
	USART_Cmd(USART2, ENABLE);                    // Enable serial port  

}


void USART2_IRQHandler(void)                	// A serial port 2 Interrupt service routine 
{
	u8 Res;
	#ifdef OS_TICKS_PER_SEC	 	// If the number of clock beats is defined , Explain to use ucosII 了 .
	OSIntEnter();    
	#endif
	if(USART_GetITStatus(USART2, USART_IT_RXNE) != RESET)  // Receive interrupt ( The data received must be 0x0d 0x0a ending )
	{
		Res =USART_ReceiveData(USART2);//(USART1->DR);	// Read received data 
		
		if((USART_RX_STA&0x8000)==0)// Reception is not complete 
		{
			if(USART_RX_STA&0x4000)// received 0x0d
			{
				if(Res!=0x0a)USART_RX_STA=0;// Receive error , restart 
				else USART_RX_STA|=0x8000;	// The reception is complete  
			}
			else // I haven't received 0X0D
			{	
				if(Res==0x0d)USART_RX_STA|=0x4000;
				else
				{
					USART_RX_BUF[USART_RX_STA&0X3FFF]=Res ;
					USART_RX_STA++;
					if(USART_RX_STA>(USART_REC_LEN-1))USART_RX_STA=0;// Receiving data error , Start receiving again 	  
				}		 
			}
		}   		 
	 } 
	#ifdef OS_TICKS_PER_SEC	 	// If the number of clock beats is defined , Explain to use ucosII 了 .
	OSIntExit();  											 
	#endif
}
 

#endif	

 

The rest USRT3-USART5 Are implemented in the same way , But here's the thing , But open multiple at the same time USART Pay attention to setting priorities .

The effect is , What characters do you send to SCM , He will return you any character , Display in serial assistant .