C51 Microcontroller 3-Digit Display Implementation

Code Example:

#include <reg52.h>

#define uchar unsigned char
#define uint unsigned int

sbit DIGIT_SELECT = P2^7;  // Digit selection latch
sbit SEGMENT_SELECT = P2^6; // Segment selection latch

const uchar digit_patterns[] = {
    0x3F,  // "0"
    0x06,  // "1"
    0x5B,  // "2"
    0x4F,  // "3"
    0x66,  // "4"
    0x6D,  // "5"
    0x7D,  // "6"
    0x07,  // "7"
    0x7F,  // "8"
    0x6F   // "9"
};

void delay_ms(uint ms) {
    uint i, j;
    for(i = ms; i > 0; i--)
        for(j = 114; j > 0; j--);
}

void show_number(uint num) {
    uchar hundreds = num / 100;
    uchar tens = (num % 100) / 10;
    uchar units = num % 10;

    // Display hundreds digit
    P0 = 0xFF;
    DIGIT_SELECT = 1;
    P0 = 0xFE;
    DIGIT_SELECT = 0;

    SEGMENT_SELECT = 1;
    P0 = digit_patterns[hundreds];
    SEGMENT_SELECT = 0;
    delay_ms(5);

    // Display tens digit
    P0 = 0xFF;
    DIGIT_SELECT = 1;
    P0 = 0xFD;
    DIGIT_SELECT = 0;

    SEGMENT_SELECT = 1;
    P0 = digit_patterns[tens];
    SEGMENT_SELECT = 0;
    delay_ms(5);

    // Display units digit
    P0 = 0xFF;
    DIGIT_SELECT = 1;
    P0 = 0xFB;
    DIGIT_SELECT = 0;

    SEGMENT_SELECT = 1;
    P0 = digit_patterns[units];
    SEGMENT_SELECT = 0;
    delay_ms(5);
}

void main() {
    while(1) {
        show_number(123); // Change this value to display different numbers
    }
}

Implementation Notes:

1. The pin definitionss (DIGIT_SELECT and SEGMENT_SELECT) should be adjusted accroding to your specific hardware configuration.
2. The show_number() function parameter determines the displayed value (must be a 3-digit number).
3. This implementation uses a common cathode 7-segment display with the specified digit paterns.