Microcontroller Exercise - Simulating a Phone Keypad

Because the course has a single-chip microcomputer, today I took out the TX-B development board I bought last year to play with it. I wrote a single-chip microcomputer program about row and column scanning.
Reference: Matrix keyboard detection

Connection circuit diagram of keyboard and single-chip microcomputer Connection

circuit diagram of 6-bit digital tube and single-chip microcomputer


Common cathode digital tube digital coding

The four rows of the matrix keyboard are connected to P3.0-P3.3 respectively, and the four columns are connected to P3.4-P3.7 respectively.

The code is written using "KeilC51v612", and the code is as follows:

Phone Keypad

  1#include

  2//Simulate the telephone keypad, press a key, and the corresponding value will be displayed. The rows and columns are arranged in the 3 x 4 way of ordinary telephones.

  3unsigned char t, key, a, count;

  4

  5sbit light8 = P1^7;

  6//Latch end of the latch that controls the digital tube segment selection. Latch after the falling edge, that is, first set dula = 1, then set dula = 0 to complete the latch

  7sbit dula=P2^6;  

  8//Latch end of the latch that controls the digital tube bit selection process is similar to dula

  9sbit wela=P2^7; 

 10

 11unsigned char code table[]={0x3f,0x06,0x5b,0x4f,0x66,

 12 0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71}; //0-F digital tube coding

 13void display(unsigned char num) //digital tube display function

 14{

 15 P0=table[num]; //Send the numth display code to the P0 port and then to the bus

 16 dula=1; //Generate a falling edge to latch the data

 17 dula=0;

 18 P0 = 0xc0;

 19 wela=1; //same as dula

 20 wela=0;

 twenty one}

 twenty two

 23//Get the key value by checking the columns. base is the value of the first column of each row. The rows and columns here are arranged in the 3 x 4 format of ordinary phones.

 24unsigned char getKey(unsigned char da, unsigned char base)

 25{

 26 switch(da)

 27 {

 28 case 0xe0: //Detect the first column

 29 return base;

 30 case 0xd0: //Detect the second column

 31 return base + 1;

 32 case 0xb0: //Detect the third column

 33 return base + 2;

 34 default : //Others return the value of the last press

 35 return key;

 36 }

 37}

 38

 39//Wait for the key to be released. If the key is still pressed, light up the LED 8.

 40void wait()

 41{

 42 while(t != 0xf0)

 43 {

 44 t = P3;

 45 t = t & 0xf0;

 46 light8 = 0;

 47 }

 48 light8 = 1;

 49}

 50

 51//Delay function, for example, if i=10, the delay is about 10ms.

 52void delay(unsigned char i)

 53{

 54 unsigned char j, k;

 55 for(j = i; j > 0; j--)

 56 {

 57 for(k = 125; k > 0; k--);

 58 }

 59}

 60

 61void main()

 62{

 63 dula = 0; //Initialize dula and wela

 64 wela = 0;

 65 while(1) 

 66 {

 67 a = 0xfe; //Check the first line first

 68 for(count = 0; count < 4; count ++)

 69 {

 70 P3 = a;

 71 t = P3 & 0xf0; //Read P3 port

 72 if(t != 0xf0) //Judge whether a key is pressed

 73 {

 74 delay(10); //delay 10ms to de-bounce

 75 t = P3 & 0xf0; // Check again whether a key is pressed

 76 if(t != 0xf0)

 77 {

 78 switch(count) //Determine which row has a key pressed

 79 {

 80 case 0:

 81 key = getKey(t, 1); //Get the key value of the first row

 82 break;

 83 case 1:

 84 key = getKey(t, 4);

 85 break;

 86 case 2:

 87 key = getKey(t, 7);

 88 break;

 89 case 3:

 90 if(t == 0xd0) //Check if a key is pressed in row 4, column 2

 91 key = 0;

 92 break;

 93 }

 94 wait();

 95 display(key);

 96 P1 = a; //Prompt which row has a key pressed

 97 }

 98 }

 99 a = (a << 1) | (a >> 7); //Continue to detect the next line, circularly shift left one bit to achieve

100 }

101 }

102}

Haha, my major is very strange, I have to master both software and hardware. I often can't grasp the direction, so I have to learn both. But I still think software is more suitable for me.
Thanks to Brother Guo's experimental board, it is also with this board that I can quickly develop a great interest in single-chip microcomputers.

 Functional diagram of TX-1B experimental board (currently replaced by TX-1C)