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The printf function is realized through the serial port, and the serial port data reception is realized by interrupt
2022-07-07 00:51:00 【Heavy vehicle water】
stm32 The project can be used directly C Standard library functions , among printf Function is not fully implemented , A back door is reserved fputc function , By implementing fputc Print to serial port to realize printf The function of .
1.fputc Format :
int fputc(int ch,FILE *F) { //...... }
//stm32 Run the program on the development board , If the host runs the debugger , The program will use the input and output devices of the host
// This is called semi host mode ,printf If you want to print through serial port , Half host mode must be turned off #pragma import(__use_no_semihosting)
struct __FILE{ int handle; };
FILE __stdout;
// Definition _sys_exit Function avoid using semi host mode
void _sys_exit(int x) { x = x; } // redefinition fputc
int fputc(int ch,FILE *F) { // send out USART_SendData(USART1,ch);
// Wait for the last data to be sent
while(USART_GetFlagStatus(USART1,USART_FLAG_TC)!=SET); return ch; }
———————————————————————————————————————————
2. Use interrupt to receive serial port
When the serial port sends data is determined by CPU decision , There is no problem of invalid waiting , Interrupts can be avoided , But the reception of serial port is not controlled by CPU Decide when to receive , If polling is also used, there will be a lot of invalid waiting , At this time, interrupt should be used to provide efficiency .
Serial port interrupt is similar to timer interrupt , Interrupt switches and NVIC.
NVIC_Init(...);// Initialization function
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);// Turn on receive interrupt
Complete the data reception in the serial port interrupt processing function
void USART1_IRQHandler(void) {
// Determine whether it is a receive interrupt ---------- USART_GetITStatus(USART1, USART_IT_RXNE);
// receive data ------------------- data = USART_ReceiveData(USART1);
// Clear interrupt flag --------------- USART_ClearITPendingBit(USART1, USART_IT_RXNE);
}
practice :
Realize data receiving and control command control for serial port interrupt, and control the main function functions of buzzer
#include <stm32f4xx.h>
#include <usart.h>
#include <stdio.h>
#include <string.h>
#include <includes.h>
//stm32 Run the program on the development board , If the host runs the debugger , The program will use the input and output devices of the host
// This is called semi host mode ,printf If you want to print through serial port , Half host mode must be turned off
#pragma import(__use_no_semihosting)
struct __FILE{
int handle;
};
FILE __stdout;
// Definition _sys_exit Function avoid using semi host mode
void _sys_exit(int x)
{
x = x;// The assignment here has no practical significance , Avoid empty functions
}
// redefinition fputc
int fputc(int ch,FILE *F)
{
// Wait for the last data to be sent
while(USART_GetFlagStatus(USART1,USART_FLAG_TC)!=SET);
// send out
USART_SendData(USART1,ch);
return ch;
}
void usart1_init(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
USART_InitTypeDef USART_InitStruct;
NVIC_InitTypeDef NVIC_InitStruct;
//1. Turn on GPIOA and USART1 The clock
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);
//2. To configure PA9 PA10 Serial port function
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;// Reuse mode
GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;// Push pull output
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;// High speed
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;// No up and down
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_9|GPIO_Pin_10;
GPIO_Init(GPIOA,&GPIO_InitStruct);
GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1);
GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1);
//3. Initialize serial port 8N1
USART_InitStruct.USART_BaudRate = 115200;// Baud rate
USART_InitStruct.USART_WordLength = USART_WordLength_8b;//8 Digit bit
USART_InitStruct.USART_StopBits = USART_StopBits_1;//1 Bit stop bit
USART_InitStruct.USART_Parity = USART_Parity_No;// No verification
USART_InitStruct.USART_Mode = USART_Mode_Rx|USART_Mode_Tx;// Send receive mode
USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;// No hardware flow control
USART_Init(USART1,&USART_InitStruct);
//4. Open serial port receive interrupt ( Clear interrupt flag )
USART_ClearITPendingBit(USART1, USART_IT_RXNE);
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
//5. initialization NVIC
NVIC_InitStruct.NVIC_IRQChannel = USART1_IRQn;// A serial port 1 Interrupt channel
NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0x2;// preemption
NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0x2;// Response priority
NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;// Can make
NVIC_Init(&NVIC_InitStruct);
//. Enable serial port
USART_Cmd(USART1,ENABLE);
}
// Send a character ( polling )
void uart1_putc(char ch)
{
// Wait for the last data to be sent
while(USART_GetFlagStatus(USART1,USART_FLAG_TC)!=SET);
USART_SendData(USART1,ch);
}
// Send string
void uart1_puts(const char *s)
{
while(*s){
uart1_putc(*s++);
}
}
volatile u32 uart_flag = 0;// Record whether the serial port has received a complete data 1--- complete
volatile u8 uart_buf[64] = {0};// Record the data received by the serial port
volatile u32 uart_cnt = 0;// Record the length of data received by the serial port
// Processing serial port command function
void parse_cmd(void)
{
while(1){
if(uart_flag){
//BEEP command
if(strstr((char *)uart_buf,"beep")){
if(strstr((char *)uart_buf,"on")){
BEEP = 1;
printf("beep on!\r\n");
}
if(strstr((char *)uart_buf,"off")){
BEEP = 0;
printf("beep off!\r\n");
}
}
else{// Illegal orders
printf("unknow command = %s\r\n",(char *)uart_buf);
}
// The processing completion flag is clear 0, Buffer emptying , Count 0
uart_flag = 0;
memset((char *)uart_buf,0,sizeof(uart_buf));
uart_cnt = 0;
}
}
}
// A serial port 1 Interrupt handling function
void USART1_IRQHandler(void)
{
//u8 data;
if(USART_GetITStatus(USART1, USART_IT_RXNE)==SET){
// Receive serial data
uart_buf[uart_cnt++] = USART_ReceiveData(USART1);
// Judge whether the data reception is completed ------ With * end
if(uart_buf[uart_cnt-1]=='*'||uart_cnt>=sizeof(uart_buf)){
uart_flag = 1;
}
// Original route
//uart1_putc(data);
USART_ClearITPendingBit(USART1, USART_IT_RXNE);
}
}
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