LED

1. Turn an LED on
2. Turn a digit LED on
3. count down

hardware

• STC89C52RC

Cathode Share LED digt codes

digit	code
0	0x3f
1	0x06
2	0x5b
3	0x4f
4	0x66
5	0x6d
6	0x7d
7	0x07
8	0x7f
9	0x6f
A	0x77
B	0x7c
C	0x39
D	0x5e
E	0x79
F	0x71
	0x00

code

#include <reg52.h>

void delay (unsigned int xms);

void main()
{
    int i = 0;
    while(1)
    {
        P1 = 0xfe; // 1111 1110
        for (i = 0; i < 8; i++)
        {
            delay(1000);
            P1 <<= 1; // P1 = P1 << 1;
            P1 = P1 | 0x01;
        }
    }
}

void delay (unsigned int xms)
{
    unsigned int i,j;
    for (i = xms; i > 0; i--)
        for(j = 112; j < 0; j--);
}

digit display

#include <reg52.h>
#define duan P0

sbit wei1 = P2^4;
sbit wei2 = P2^5;
sbit wei3 = P2^6;
sbit wei4 = P2^7;

void main()
{
    wei1 = 1;
    wei2 = 0;
    wei3 = 0;
    wei4 = 0;

    duan = 0x7c; // 0111 1100 "b"
    while(1);
}

LED digit dynamic display

#include <reg52.h>
#define duan P0
#define uchar unsigned char

sbit wei1 = P2^4;
sbit wei2 = P2^5;
sbit wei3 = P2^6;
sbit wei4 = P2^7;

uchar code sz[17] = {
    0x3f,
    0x06,
    0x5b,
    0x4f,
    0x66,
    0x6d,
    0x7d,
    0x07,
    0x7f,
    0x6f,
    0x77,
    0x7c,
    0x39,
    0x5e,
    0x79,
    0x71,
    0x00
};

void delay (unsigned int xms)
{
    unsigned int i,j;
    for (i = xms; i > 0; i--)
        for(j = 112; j < 0; j--);
}

void main()
{
    while(1)
    {
        duan = sz[4];
        wei1 = 0;
        wei2 = 0;
        wei3 = 0;
        wei4 = 1;
        delay(1000);
        duan = sz[3];
        wei1 = 0;
        wei2 = 0;
        wei3 = 1;
        wei4 = 0;
        delay(1000);
        duan = sz[2];
        wei1 = 0;
        wei2 = 1;
        wei3 = 0;
        wei4 = 0;
        delay(1000);
        duan = sz[1];
        wei1 = 1;
        wei2 = 0;
        wei3 = 0;
        wei4 = 0;
        delay(1000);
    }
}