基于USART接口的通信技术 - 中科因仑“3+1”工程特种兵精英论坛

/*******************************************************
* 程序功能：USART的数据发送和接收
* 接线说明：核心板PD0和PD1短接，PA0~PA7接到静态数码管显示电路
* 实验现象：数码管从0加到9如此循环
* 日期 : 2014/07/31
* 作者 : 翟志刚
*******************************************************/
#include <iom16v.h>
#include <macros.h>
#define uchar unsigned char
#define uint unsigned int
#define BAUD 9600 //波特率采用9600bps
#define CRYSTAL 1000000 //系统时钟1MHz
//计算和定义波特率设置参数
#define BAUD_SETTING (unsigned int)((unsigned long)CRYSTAL/(16*(unsigned long)BAUD)-1)
#define BAUD_H (unsigned char)(BAUD_SETTING>>8)
#define BAUD_L (unsigned char)(BAUD_SETTING)
// USART控制和状态寄存器的标志位定义
#define RXC 7 // UCSRA位定义
#define TXC 6
#define UDRE 5
#define FE 4
#define DOR 3
#define PE 2
#define U2X 1
#define MPCM 0
#define RXCIE 7 // UCSRB位定义
#define TXCIE 6
#define UDRIE 5
#define RXEN 4
#define TXEN 3
#define UCSZ2 2
#define RXB8 1
#define TXB8 0
#define URSEL 7 // UCSRC位定义
#define UMSEL 6
#define UPM1 5
#define UPM0 4
#define USBS 3
#define UCSZ1 2
#define UCSZ0 1
#define UCPOL 0
#define FRAMING_ERROR (1<<FE)
#define PARITY_ERROR (1<<PE)
#define DATA_OVERRUN (1<<DOR)
#define DATA_REGISTER_EMPTY (1<<UDRE)
uchar led_7[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F};
uchar i = 0;
uchar counter = 0;
// USART接收结束中断服务程序
#pragma interrupt_handler USART_RXC:12
void USART_RXC(void) // USART接收中断服务
{
uchar status,data;
status = UCSRA;
data = UDR;
if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
PORTA = led_7[data];
}
void USART_Transmit(unsigned char data)
{
while (!(UCSRA & DATA_REGISTER_EMPTY)); // 等待发送寄存器空
UDR = data; // 发送数据
}
/*定时器0溢出中断服务程序*/
#pragma interrupt_handler timer0_ovf:10
void timer0_ovf(void)
{
counter++;
if(counter == 4)
{
USART_Transmit(i);
PORTB=~PORTB;
if (++i >= 10) i = 0;
counter = 0;
}
}
void main( void )
{
DDRA = 0xff; // LED段码输出
PORTA = 0x00;
DDRB = 0xff;
PORTB = 0xFF; // LED灯输出
PORTD = 0x03; // TXD(PD1)输出
DDRD = 0x02; // RXD(PD0)输入,上拉有效
UCSRA = 0x00; // USART初始化
UCSRB = (1<<RXCIE)|(1<<RXEN)|(1<<TXEN); // 允许RXC中断,接收允许,发送允许
UCSRC = (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0); // 8 Data, 1 Stop, No Parity
UBRRH = BAUD_H; // 设置波特率
UBRRL = BAUD_L;
TIMSK |= (1<<TOIE0); //使能T0溢出中断
TCCR0 = 0x05; //配置定时器工作普通模式
TCNT0 = 0xff; //给定时器赋初值
SREG=0x80; // 开全局中断
while(1)
{
};
}

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