Programming tips: AVR UART data transmission and reception test program-EEWORLD

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This program implements the UART interrupt mode to send and receive data, and sends the received data immediately to form a loop.

It consists of the test program , the related header file , and the UART data processing program .

/* ************************************************
* File name: main.c
* Function: AVR's UART data receiving and sending test program
* Description: Forward the data received by the RXD port to the TXD port
* The receiving and sending work is automatically completed by the UART interrupt
* Author & Date: Joshua Chan, 2012/03/28
* ************************************************/
#include
#include
#include
#include
#include
#include "uart_test.h"

/* Test program: Send the data received by the serial port as is*/
void main(void)
{
unsigned char data;

fifo_pos_init(); /* Reset position record*/
uart_init(B9600); /* Initialize UART */
_SEI();
while (1) {
if ((data = rx_byte()) != NONE_DATA)
tx_byte(data);
_WDR(); /* Feed the dog*/
}
}

/* ************************************************
* File name: uart_test.h
* Function: AVR's UART data receiving and sending test program
* Description: Forward the data received by the RXD port to the TXD port
* The receiving and sending work is automatically completed by the UART interrupt
* Author & Date: Joshua Chan, 2012/03/28
* ************************************************/
#ifndef _UART_TEST_H
#define _UART_TEST_H

/* Define the UBRR value when FOSC=16.0MHz*/
__flash enum baudrate {
B2400 = 416,
B4800 = 207,
B9600 = 103,
B14400 = 68,
B19200 = 51,
B28800 = 34,
B38400 = 25,
B57600 = 16,
B76800 = 12,
B115200 = 8,
B230400 = 3,
};

#define NONE_DATA '\4' /* No new data flag*/
#define RX_BUF_SIZE 32 /* Receive buffer size*/
#define TX_BUF_SIZE 32 /* Transmit buffer size*/

/* Reset position record*/
extern void fifo_pos_init(void);

/* UART initialization*/
extern void uart_init(unsigned int baud);

/* Read 1 byte from the receive buffer*/
extern unsigned char rx_byte(void);

/* Send 1 byte of data to the transmit buffer and enable the data register empty interrupt*/
extern void tx_byte(unsigned char data);

#endif

/* ************************************************
 * File name: uart_test.c
 * Function: AVR UART data receiving and sending test program
 * Description: Forward the data received by the RXD port to the TXD port
 * Transmission and reception are automatically completed by UART interrupt
 * Author & Date: Joshua Chan, 2012/03/28
 * ************************************************/
#include 
#include 
#include 
#include 
#include 
#include "uart_test.h"

unsigned char rx_fifo[RX_BUF_SIZE]; /* Receive buffer */
unsigned char tx_fifo[TX_BUF_SIZE]; /* Send buffer */
unsigned char rx_pos; /* The position of the last received data in the buffer*/
unsigned char read_pos; /* The position of the last data read in the buffer*/
unsigned char tx_pos; /* The position of the last transmitted data in the buffer*/
unsigned char write_pos; /* The position of the last written data in the buffer*/

/* UART initialization */
void uart_init(unsigned int baud)
{
    /* Disable USART function first */
    UCSR0B = 0x00;
    /* Set baudrate */
    UBRR0H = (unsigned char)(baud>>8);
    UBRR0L = (unsigned char)baud;
    /* Set frame format: 8 data bits, 1 stop bit*/
    UCSR0C = 3 << UCSZ00;
    /* Enable: receive end interrupt, receive, send*/
    UCSR0B = (1<

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