Question

求大神帮写一个51单片机的小程序。用4×4键盘

数码管显示数字0；按任意键开始计数，每1秒加1；个位进十位时暂停计数，按下任意键继续计数；计数过程中，按下任意键，暂停计数，再按下任意键恢复计数。

Answer 1

#include<reg51.h>

//Function declarations
void cct_init(void);
void delay(int);
void lcdinit(void);
void writecmd(int);
void writedata(char);
void Return(void);
char READ_SWITCHES(void);
char get_key(void);

//*******************
//Pin description
/*
P2 is data bus
P3.7 is RS
P3.6 is E
P1.0 to P1.3 are keypad row outputs
P1.4 to P1.7 are keypad column inputs
*/
//********************
// Define Pins
//********************
sbit RowA = P1^0;     //RowA
sbit RowB = P1^1;     //RowB
sbit RowC = P1^2;     //RowC
sbit RowD = P1^3;     //RowD

sbit C1   = P1^4;     //Column1
sbit C2   = P1^5;     //Column2
sbit C3   = P1^6;     //Column3
sbit C4   = P1^7;     //Column4

sbit E    = P3^6;     //E pin for LCD
sbit RS   = P3^7;     //RS pin for LCD

// ***********************************************************
// Main program
//
int main(void)
{
   char key;                // key char for keeping record of pressed key

   cct_init();              // Make input and output pins as required
   lcdinit();               // Initilize LCD

   writecmd(0x95);
   writedata('w');                                 //write
   writedata('w');                                 //write
   writedata('w');                                 //write
   writedata('.');                                 //write
   writedata('T');                                 //write
   writedata('h');                                 //write
   writedata('e');                                 //write
   writedata('E');                                 //write
   writedata('n');                                 //write
   writedata('g');                                 //write
   writedata('i');                                 //write
   writedata('n');                                 //write
   writedata('e');                                 //write
   writedata('e');                                 //write
   writedata('r');                                 //write
   writedata('i');                                 //write
   writedata('n');                                 //write
   writedata('g');                                 //write
 
   writecmd(0xd8);
 
   writedata('P');                                 //write
   writedata('r');                                 //write
   writedata('o');                                 //write
   writedata('j');                                 //write
   writedata('e');                                 //write
   writedata('c');                                 //write
   writedata('t');                                 //write
   writedata('s');                                 //write
   writedata('.');                                 //write
   writedata('c');                                 //write
   writedata('o');                                 //write
   writedata('m');                                 //write
   writecmd(0x80);
   while(1)
   { 
     key = get_key();       // Get pressed key
     //writecmd(0x01);        // Clear screen
     writedata(key);        // Echo the key pressed to LCD
   }
}


void cct_init(void)
{
    P0 = 0x00;   //not used
    P1 = 0xf0;   //used for generating outputs and taking inputs from Keypad
    P2 = 0x00;   //used as data port for LCD
    P3 = 0x00;   //used for RS and E   
}

void delay(int a)
{
   int i;
   for(i=0;i<a;i++);   //null statement
}

void writedata(char t)
{
   RS = 1;             // This is data
   P2 = t;             //Data transfer
   E  = 1;             // => E = 1
   delay(150);
   E  = 0;             // => E = 0
   delay(150);
}


void writecmd(int z)
{
   RS = 0;             // This is command
   P2 = z;             //Data transfer
   E  = 1;             // => E = 1
   delay(150);
   E  = 0;             // => E = 0
   delay(150);
}

void lcdinit(void)
{
  ///////////// Reset process from datasheet /////////
     delay(15000);
   writecmd(0x30);
     delay(4500);
   writecmd(0x30);
     delay(300);
   writecmd(0x30);
     delay(650);
  /////////////////////////////////////////////////////
   writecmd(0x38);    //function set
   writecmd(0x0c);    //display on,cursor off,blink off
   writecmd(0x01);    //clear display
   writecmd(0x06);    //entry mode, set increment
}

void Return(void)     //Return to 0 location on LCD
{
  writecmd(0x02);
    delay(1500);
}

char READ_SWITCHES(void)    
{    
    RowA = 0; RowB = 1; RowC = 1; RowD = 1;     //Test Row A

    if (C1 == 0) { delay(10000); while (C1==0); return '7'; }
    if (C2 == 0) { delay(10000); while (C2==0); return '8'; }
    if (C3 == 0) { delay(10000); while (C3==0); return '9'; }
    if (C4 == 0) { delay(10000); while (C4==0); return '/'; }

    RowA = 1; RowB = 0; RowC = 1; RowD = 1;     //Test Row B

    if (C1 == 0) { delay(10000); while (C1==0); return '4'; }
    if (C2 == 0) { delay(10000); while (C2==0); return '5'; }
    if (C3 == 0) { delay(10000); while (C3==0); return '6'; }
    if (C4 == 0) { delay(10000); while (C4==0); return 'x'; }
    
    RowA = 1; RowB = 1; RowC = 0; RowD = 1;     //Test Row C

    if (C1 == 0) { delay(10000); while (C1==0); return '1'; }
    if (C2 == 0) { delay(10000); while (C2==0); return '2'; }
    if (C3 == 0) { delay(10000); while (C3==0); return '3'; }
    if (C4 == 0) { delay(10000); while (C4==0); return '-'; }
    
    RowA = 1; RowB = 1; RowC = 1; RowD = 0;     //Test Row D

    if (C1 == 0) { delay(10000); while (C1==0); return 'C'; }
    if (C2 == 0) { delay(10000); while (C2==0); return '0'; }
    if (C3 == 0) { delay(10000); while (C3==0); return '='; }
    if (C4 == 0) { delay(10000); while (C4==0); return '+'; }

    return 'n';               // Means no key has been pressed
}

char get_key(void)           //get key from user
{
    char key = 'n';              //assume no key pressed

    while(key=='n')              //wait untill a key is pressed
        key = READ_SWITCHES();   //scan the keys again and again

    return key;                  //when key pressed then return its value
}