STC89C52RC型号的51单片机编程能用if(P2==0xFE)这样的语句吗

可以使用if语句来判断51单片机端口P2的状态。在STC89C52RC型号的51单片机中，P2是8位的端口，可以直接通过P2寄存器来读取其状态。

if(P2 == 0xFE)语句的作用是判断P2的值是否等于0xFE。如果等于，条件成立，执行if语句中的代码块；如果不等于，条件不成立，跳过if语句中的代码块。

请注意，在使用if语句之前，需要先对P2端口进行初始化和配置。同时，要根据具体的应用需求，确定P2端口的工作模式，如输入模式、输出模式等。

相关问题

用stc89c52rc单片机为辅机和stc15w408as单片机为主机进行串口通信的代码，让stc89c52rc单片机通过矩阵按键1或者2发送指令，stc15w408as单片机进行接收，相对应按键后让P5^4为引脚的LED亮，让stc89c52rc单片机在ld1602显示的温度数加1，相反减1

以下是用stc89c52rc单片机为辅机和stc15w408as单片机为主机进行串口通信的代码：

stc89c52rc单片机代码：

#include <reg52.h>
#include <intrins.h>

#define FOSC 11059200L
#define BAUD 9600
#define TIMER_1MS (65536-FOSC/12/1000)

sbit Matrix1 = P2^0;
sbit Matrix2 = P2^1;

unsigned char TxdData;
unsigned char ReceiveData;
unsigned char TxdFlag = 0;

void SendData(unsigned char dat);
void DelayMs(unsigned int ms);
void InitUart();
void MatrixScan();

void main()
{
    InitUart();
    while(1)
    {
        MatrixScan();
        if(Matrix1 == 0)
        {
            SendData('1');
            while(Matrix1 == 0);
            P5^4 = 1;
            DelayMs(10);
            P5^4 = 0;
        }
        if(Matrix2 == 0)
        {
            SendData('2');
            while(Matrix2 == 0);
            P5^4 = 1;
            DelayMs(10);
            P5^4 = 0;
        }
    }
}

void SendData(unsigned char dat)
{
    SBUF = dat;
    while(!TxdFlag);
    TxdFlag = 0;
}

void DelayMs(unsigned int ms)
{
    unsigned int i,j;
    for(i=ms; i>0; i--)
        for(j=110; j>0; j--);
}

void InitUart()
{
    TMOD &= 0x0F;
    TMOD |= 0x20;
    TH1 = TIMER_1MS / BAUD;
    TL1 = TIMER_1MS % BAUD;
    TR1 = 1;
    ES = 1;
    EA = 1;
}

void MatrixScan()
{
    unsigned char i;
    static unsigned char code KeyTable[] =
    {
        0x7f,0xbf,0xdf,0xef,
        0xf7,0xfb,0xfd,0xfe
    };
    for(i=0; i<8; i++)
    {
        P1 = KeyTable[i];
        _nop_();
        if((P1 & 0x0f) != 0x0f)
            break;
    }
    if(i < 8)
    {
        switch(i)
        {
            case 0: ReceiveData = '1'; break;
            case 1: ReceiveData = '4'; break;
            case 2: ReceiveData = '7'; break;
            case 3: ReceiveData = '*'; break;
            case 4: ReceiveData = '2'; break;
            case 5: ReceiveData = '5'; break;
            case 6: ReceiveData = '8'; break;
            case 7: ReceiveData = '0'; break;
            default: break;
        }
    }
    else ReceiveData = 0;
}

void UartIsr() interrupt 4
{
    if(RI)
    {
        RI = 0;
        ReceiveData = SBUF;
        if(ReceiveData == '1')
        {
            P5^4 = 1;
            DelayMs(10);
            P5^4 = 0;
        }
        if(ReceiveData == '2')
        {
            P5^4 = 1;
            DelayMs(10);
            P5^4 = 0;
        }
    }
    if(TI)
    {
        TI = 0;
        TxdFlag = 1;
    }
}

stc15w408as单片机代码：

#include <REG52.H>
#include <stdio.h>

#define FOSC 22118400L
#define BAUD 9600
#define TIMER_1MS (65536-FOSC/12/1000)

sbit LED = P5^4;

unsigned char TxdData;
unsigned char ReceiveData;
unsigned char Temperature = 25;
unsigned char TxdFlag = 0;

void SendData(unsigned char dat);
void InitUart();
void InitTimer0();
void Timer0Isr() interrupt 1;
void UartIsr() interrupt 4;

void main()
{
    InitUart();
    InitTimer0();
    while(1);
}

void SendData(unsigned char dat)
{
    SBUF = dat;
    while(!TxdFlag);
    TxdFlag = 0;
}

void InitUart()
{
    TMOD &= 0x0F;
    TMOD |= 0x20;
    TH1 = TIMER_1MS / BAUD;
    TL1 = TIMER_1MS % BAUD;
    TR1 = 1;
    ES = 1;
    EA = 1;
}

void InitTimer0()
{
    TMOD &= 0xF0;
    TMOD |= 0x01;
    TH0 = TIMER_1MS / 1000;
    TL0 = TIMER_1MS % 1000;
    ET0 = 1;
    EA = 1;
    TR0 = 1;
}

void Timer0Isr() interrupt 1
{
    TH0 = TIMER_1MS / 1000;
    TL0 = TIMER_1MS % 1000;
    Temperature++;
    if(Temperature > 40)
        Temperature = 25;
}

void UartIsr() interrupt 4
{
    if(RI)
    {
        RI = 0;
        ReceiveData = SBUF;
        if(ReceiveData == '1')
            LED = 1;
        if(ReceiveData == '2')
            LED = 0;
    }
    if(TI)
    {
        TI = 0;
        TxdFlag = 1;
    }
}

#include<reg51.h> void delay(unsigned int xms){ //ÑÓʱº¯Êý unsigned int i, j; for(i=0; i<xms; ++i) for(j=0; j<110; ++j); } void main(){ while(1) { while(P0==0xFE) { P2=0xFE; delay(200); P2=0xFD; delay(200); P2=0xFB; delay(200); P2=0xF7; delay(200); P2=0xEF; delay(200); P2=0xDF; delay(200); P2=0xBF; delay(200); P2=0x7F; delay(200); } while(P0==0xFD) { P2=0xFE; delay(200); P2=0xFD; delay(200); P2=0xFC; delay(200); P2=0xFB; delay(200); P2=0xEA; delay(200); P2=0xDF; delay(200); P2=0xBE; delay(200); P2=0x7D; delay(200); } while(P0==0xFB) { P2=0xFA; delay(200); P2=0xF4; delay(200); P2=0xF6; delay(200); P2=0xF7; delay(200); P2=0xA4; delay(200); P2=0x56; delay(200); P2=0x47; delay(200); P2=0x7F; delay(200); } while(P0==0xF7) { P2=0xFE; delay(50); P2=0xFD; delay(50); P2=0xFB; delay(50); P2=0xF7; delay(50); P2=0xEF; delay(50); P2=0xDF; delay(50); P2=0xBF; delay(50); P2=0x7F; delay(50); } while(P0==0xEF) { P2=0xFE; delay(50); P2=0xFD; delay(50); P2=0xFC; delay(50); P2=0xFB; delay(50); P2=0xEA; delay(50); P2=0xDF; delay(50); P2=0xBE; delay(50); P2=0x7D; delay(50); } while(P0==0xDF) { P2=0xFF; delay(500); P2=0x00; delay(500); } while(P0==0xBF) { P2=0xEA; delay(200); P2=0xDF; delay(200); P2=0xBD; delay(200); P2=0x7E; delay(200); } while(P0==0x7F) { P2=0xFF; delay(500); } } }

这段代码看起来是在控制 LED 灯的亮灭，但是代码结构比较混乱，建议可以进行如下的优化：

1. 引入宏定义，将常数定义为宏进行使用，方便后续修改和维护。
2. 将 LED 灯控制的代码封装成一个函数，方便后续调用和维护。
3. 使用 switch-case 语句替换多个嵌套的 while 循环，提高代码可读性和可维护性。

下面是优化后的代码，供您参考：

#include <reg51.h>

#define DELAY_TIME 200
#define SHORT_DELAY_TIME 50
#define LONG_DELAY_TIME 500

void delay(unsigned int xms) {
    unsigned int i, j;
    for (i = 0; i < xms; ++i) {
        for (j = 0; j < 110; ++j);
    }
}

void controlLED(unsigned char value) {
    switch (value) {
        case 0xFE:
            P2 = 0xFE;
            delay(DELAY_TIME);
            P2 = 0xFD;
            delay(DELAY_TIME);
            P2 = 0xFB;
            delay(DELAY_TIME);
            P2 = 0xF7;
            delay(DELAY_TIME);
            P2 = 0xEF;
            delay(DELAY_TIME);
            P2 = 0xDF;
            delay(DELAY_TIME);
            P2 = 0xBF;
            delay(DELAY_TIME);
            P2 = 0x7F;
            delay(DELAY_TIME);
            break;
        case 0xFD:
            P2 = 0xFE;
            delay(DELAY_TIME);
            P2 = 0xFD;
            delay(DELAY_TIME);
            P2 = 0xFC;
            delay(DELAY_TIME);
            P2 = 0xFB;
            delay(DELAY_TIME);
            P2 = 0xEA;
            delay(DELAY_TIME);
            P2 = 0xDF;
            delay(DELAY_TIME);
            P2 = 0xBE;
            delay(DELAY_TIME);
            P2 = 0x7D;
            delay(DELAY_TIME);
            break;
        case 0xFB:
            P2 = 0xFA;
            delay(DELAY_TIME);
            P2 = 0xF4;
            delay(DELAY_TIME);
            P2 = 0xF6;
            delay(DELAY_TIME);
            P2 = 0xF7;
            delay(DELAY_TIME);
            P2 = 0xA4;
            delay(DELAY_TIME);
            P2 = 0x56;
            delay(DELAY_TIME);
            P2 = 0x47;
            delay(DELAY_TIME);
            P2 = 0x7F;
            delay(DELAY_TIME);
            break;
        case 0xF7:
            P2 = 0xFE;
            delay(SHORT_DELAY_TIME);
            P2 = 0xFD;
            delay(SHORT_DELAY_TIME);
            P2 = 0xFB;
            delay(SHORT_DELAY_TIME);
            P2 = 0xF7;
            delay(SHORT_DELAY_TIME);
            P2 = 0xEF;
            delay(SHORT_DELAY_TIME);
            P2 = 0xDF;
            delay(SHORT_DELAY_TIME);
            P2 = 0xBF;
            delay(SHORT_DELAY_TIME);
            P2 = 0x7F;
            delay(SHORT_DELAY_TIME);
            break;
        case 0xEF:
            P2 = 0xFE;
            delay(SHORT_DELAY_TIME);
            P2 = 0xFD;
            delay(SHORT_DELAY_TIME);
            P2 = 0xFC;
            delay(SHORT_DELAY_TIME);
            P2 = 0xFB;
            delay(SHORT_DELAY_TIME);
            P2 = 0xEA;
            delay(SHORT_DELAY_TIME);
            P2 = 0xDF;
            delay(SHORT_DELAY_TIME);
            P2 = 0xBE;
            delay(SHORT_DELAY_TIME);
            P2 = 0x7D;
            delay(SHORT_DELAY_TIME);
            break;
        case 0xDF:
            P2 = 0xFF;
            delay(LONG_DELAY_TIME);
            P2 = 0x00;
            delay(LONG_DELAY_TIME);
            break;
        case 0xBF:
            P2 = 0xEA;
            delay(DELAY_TIME);
            P2 = 0xDF;
            delay(DELAY_TIME);
            P2 = 0xBD;
            delay(DELAY_TIME);
            P2 = 0x7E;
            delay(DELAY_TIME);
            break;
        case 0x7F:
            P2 = 0xFF;
            delay(LONG_DELAY_TIME);
            break;
        default:
            break;
    }
}

void main() {
    while (1) {
        unsigned char value = P0;
        controlLED(value);
    }
}