ATmega8模拟串口

波特率4800bps,晶振使用外部晶振11.0592.

 

主程序t2.c:

//ICC-AVR application builder : 2009-5-6 18:22:23
// Target : M8
// Crystal: 11.059Mhz

#include
#include
#include "ck.h"
void port_init(void)
{
 PORTB = 0x01;
 DDRB  = 0x00;
 PORTC = 0x00; //m103 output only
 DDRC  = 0x00;
 PORTD = 0x00; //有影响
 DDRD  = 0x60; //有影响,方向设置不对会不准
}

//Watchdog initialize
// prescale: 16K
void watchdog_init(void)
{
 WDR (); //this prevents a timeout on enabling
 WDTCR |= (1< WDTCR = 0x08; //WATCHDOG ENABLED - dont forget to issue WDRs
}

 

//SPI initialize
// clock rate: 691187hz
void spi_init(void)
{
 SPCR = 0x71; //setup SPI
 SPSR = 0x00; //setup SPI
}

//UART0 initialize
// desired baud rate: 4800
// actual: baud rate:4800 (0.0%)
void uart0_init(void)
{
 UCSRB = 0x00; //disable while setting baud rate
 UCSRA = 0x00;
 UCSRC = BIT(URSEL) | 0x06;
 UBRRL = 0x8F; //set baud rate lo
 UBRRH = 0x00; //set baud rate hi
 UCSRB = 0x90;
}

#pragma interrupt_handler uart0_rx_isr:iv_USART0_RXC
void uart0_rx_isr(void)
{
 //uart has received a character in UDR
}

//call this routine to initialize all peripherals
void init_devices(void)
{
 //stop errant interrupts until set up
 CLI(); //disable all interrupts
 port_init();
 //watchdog_init();
 //timer0_init();
 //spi_init();
 //uart0_init();

 MCUCR = 0x00;
 GICR  = 0x00;
 TIMSK = 0x00; //timer interrupt sources
 SEI(); //re-enable interrupts
 //all peripherals are now initialized
}

void delay(unsigned int ms, unsigned int us)
{
 unsigned int i;
 
 if(ms>0)//ms delay
 for(;ms;ms--)
  for(i=0;i<1000;i++);
 
 if(us>0)//us delay
   for(;us>0;us--); 
}

main()
{
 unsigned int i,j;
 init_devices();
 PORTB = 0x00;
 PORTD = 0x40;
 PORTC =0x04;
 DDRC |=0x04;
 
 while(1)
 {
   PORTD ^= 0x60;
   delay(900,0); 
  
   WByte(0x55);
 
 }
 
 return 0;
}

头文件ck.h:

#include

#define INT8U unsigned char
#define INT16U unsigned int
 

//模拟串口，波特率4800
void Delay2cp(INT16U i);
void WByte(INT8U input);// ,INT16U ii
INT8U RByte(void);
 
void TXD0(unsigned char bit)
{
 if(bit==0)
  PORTC&=0xfB;
  else PORTC|=0x04;
}
/*
void delay8(INT8U j)
{
 INT8U i;
 for(i=0;i}

void delay16(INT16U j)
{
 INT16U i;
 for(i=0;i}
*/
/*
void serial_initial(void)
{
 TMOD = 0x21;
 PCON = 0x00;
 SCON = 0x58;
 RODI = 0;
 TH1 = 0xFA;    //4800BPS
 TL1 = 0xFA;
 ES = 1;
 SERIAL_INTRPT_ENABLE;
 TR1 = 1;
}*/

/* 模拟串口
   模拟串口三个函数
*/
//延时程序*
void Delay2cp(INT16U i)
{
  unsigned de;
 
   // i = 0x172;
 
 while(i--);
  //  for(de=0;de<625;de++);      //刚好两个指令周期。
}

//void WByte(uchar)
//往串口写一个字节
void WByte(INT8U input)
{
   INT8U i = 8;
   INT16U ii=0x160;
   
   CLI();  
  
    PORTC&=0xfB;//TXD0(0);     //发送启始位TXD=0
    //Delay2cp(ii);
 Delay2cp(ii+100);
    //发送8位数据位
    while(i--)
    {
       // TXD0(input&0x01);     //先传低位
        if((input&0x01)==0)
    PORTC &= 0xfB;//output 0(L)
           else PORTC |= 0x04;//output 1(H)
  
  Delay2cp(ii);
        input = input>>1;
    }
    Delay2cp(ii);
    //发送校验位(无)
    PORTC|=0x04;// TXD0(1);   //发送结束位 TXD=1
    Delay2cp(ii);
    SEI();  
 Delay2cp(ii);
    
}