STC89C52_51单片机_串口配置_UART串口通信

寄存器配置

PCON电源管理寄存器

位序号 D7 D6 D5 D4 D3 D2 D1 D0

位符号 SM0 SM1 SM2 REN TB8 RB8 TI RI

– 模式 模式 模式1直接清零 使能串口接收 模式1接收停止位 发送标志位，软件清零 接受标志位，软件清0

//不能位寻址

SCON串口控制寄存器

位序号 D7 D6 D5 D4 D3 D2 D1 D0

位符号 SM0 SM1 SM2 REN TB8 RB8 TI RI

– 模式 模式 模式1直接清零 使能串口接收 模式1接收停止位 发送标志位，软件清零 接受标志位，软件清0

/*  SCON  */

sbit SM0   = SCON^7;

sbit SM1   = SCON^6;

sbit SM2   = SCON^5;

sbit REN   = SCON^4;

sbit TB8   = SCON^3;

sbit RB8   = SCON^2;

sbit TI    = SCON^1;

sbit RI    = SCON^0;

模式&波特率（宋雪松P183）

SCON主要用模式1，的波特率

对应的，要用定时器T1&T2的模式2

TH1 = TL1 = 256 - 晶振值/12/2/16/波特率

（256是TL1的溢出值，12指12个时钟周期，16是硬件因素）

SBUF

两个SBUF寄存器，分别负责接收和发送缓冲

流程

配置串口为模式1

配置定时器T1为模式2

根据波特率计算TH0&TL0的值

配置PCON&SCON寄存器

打开定时器

IO口模拟UART串口通信

ＵＡＲＴ串口传送数据示意图

挖坑：波特率&TH0是怎么算的？

#include

sbit PIN_RXD = P3^0;

sbit PIN_TXD = P3^1;

bit RxdOrTxd = 0;

bit RxdEnd = 0;

bit TxdEnd = 0;

unsigned char RxdBuf = 0;

unsigned char TxdBuf = 0;

void configUART(unsigned long baud);

void startRXD(void);

void startTXD(unsigned char dat);

void main(void)

{

EA = 1;

configUART(9600);

while(1)

{

while(PIN_RXD);

startRXD();

while(!RxdEnd);

startTXD(RxdBuf+1);

while(!TxdEnd);

}

}

void configUART(unsigned long baud)

{

TMOD &= ~(0xF<<0);

TMOD |= 0x1<<1;

TH0 = 256 - (11059200 / 12) / baud;

}

void startRXD(void)

{

TL0 = 256 - ((256 - TH0) >> 1);

ET0 = 1;

TR0 = 1;

RxdEnd = 0;

RxdOrTxd = 0;

}

void startTXD(unsigned char dat)

{

TxdBuf = dat;

TL0 = TH0;

ET0 = 1;

TR0 = 1;

PIN_TXD = 0;

RxdEnd = 0;

RxdOrTxd = 1;

}

void timer0(void) interrupt 1

{

static unsigned char cnt = 0;

if(RxdOrTxd)

{

cnt++;

if(cnt<=8)

{

PIN_TXD = TxdBuf & 0x01;

TxdBuf >>= 1;

}

else if(cnt==9)

{

PIN_TXD = 1;

}

else 

{

cnt = 0;

TR0 = 0;

TxdEnd = 1;

}

}

else

{

if(cnt==0)

{

if(!PIN_RXD)

{

RxdBuf = 0;

cnt++;

}

else

{

TR0 = 0;

}

}

else if(cnt<=8)

{

RxdBuf >>= 1;

if(PIN_RXD)

{

RxdBuf |= 0x80;

}

cnt++;

}

else

{

cnt = 0;

TR0 = 0;

if(PIN_RXD)

{

RxdEnd = 1;

}

}

}

}

UART串口通信

教学版

#include

void configUART(unsigned long baud);

void main(void)

{

configUART(9600);

while(!RI);

RI = 0;

SBUF = SBUF + 1;

while(!TI);

TI = 0;

}

void configUART(unsigned long baud)

{

SCON = 0x50;

TH1 = 256 - (11059200 / 12 / 2 / 16) / baud;

TL1 = TH1;

TMOD &= ~(0xF<<4);

TMOD |= 0x2<<4;

ET1 = 0;

TR1 = 1;

}

工业版

#include

void configUART(unsigned long baud);

void main(void)

{

EA = 1;

configUART(9600);

while(1);

}

void configUART(unsigned long baud)

{

SCON = 0x50;

TH1 = 256 - (11059200 / 12 / 2 / 16) / baud;

TL1 = TH0;

TMOD &= ~(0xF<<4);

TMOD |= 0x2<<4;

ET1 = 0;

ES = 1;

TR1 = 1;

}

void UART(void) interrupt 4

{

if(RI)

{

RI = 0;

SBUF = SBUF + 1;

}

if(TI)

{

TI = 0;

}

}

计算机发送数据，在数码管中显示

#include

sbit wei = P2^7;

sbit duan = P2^6;

unsigned char code weitable[6] = 

{

~0x20,~0x10,~0x08,~0x04,~0x02,~0x01

};

unsigned char code duantable[16] = 

{

0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,

0x7F,0x6F,0x77,0x7C,0x39,0x5E,0x79,0x71

};

unsigned char ledbuff[6] = 

{

0x00,0x00,0x00,0x00,0x00,0x00

};

unsigned char T0RH = 0,T0RL = 0;

unsigned char RxdByte = 0;

void configtimer0(unsigned char ms);

void configUART(unsigned long baud);

void main(void)

{

EA = 1;

configtimer0(1);

configUART(9600);

while(1)

{

ledbuff[0] = duantable[RxdByte & 0x0F];

ledbuff[1] = duantable[RxdByte >> 4];

}

}

void configtimer0(unsigned char ms)

{

unsigned long tmp;

tmp = 11059200 / 12;

tmp = (tmp * ms) / 1000;

tmp = 65536 - tmp;

tmp = tmp + 12;

T0RH = (unsigned char)(tmp>>8);

T0RL = (unsigned char)tmp;

TH0 = T0RH;

TL0 = T0RL;

TMOD &= ~(0xF<<0);

TMOD |= 0x1<<0;

ET0 = 1;

TR0 = 1;

}

void configUART(unsigned long baud)

{

TH1 = 256 - (11059200 / 12 / 2 / 16) / baud;

TL1 = TH0;

SCON = 0x50;

TMOD &= ~(0xF<<4);

TMOD |= 0x2<<4;

ET1 = 0;

ES = 1;

TR1 = 1;

}

void ledscan(void)

{

static unsigned char i = 0;

P0 = 0x00;

duan = 1;

duan = 0;

P0 = weitable[i];

wei = 1;

wei = 0;

P0 = ledbuff[i];   

duan = 1;

duan = 0;

if(i<5)

i++;

else

i = 0;

}

void timer0(void) interrupt 1

{

TH0 = T0RH;

TL0 = T0RL;

ledscan();

}

void UART(void) interrupt 4

{

if(RI)

{

RI = 0;

RxdByte = SBUF;

SBUF = RxdByte;

}

if(TI)

{

TI = 0;

}

}