Control of digital tube of C51 single chip microcomputer

Circuit Diagram

Note: In practice, the 74HC573 circuit of my microcontroller is connected in reverse with the P0 terminal.

138 decoder information: https://pan.baidu.com/s/1COTcutsnMxMSc8tq0M2yVw Password: 1jww

The truth table of 138 decoder:

74HC573 information: https://pan.baidu.com/s/1b5OJXniyd6gODyf_eA_sXA Password: m7zx

If you have studied digital electronics, you can take a quick look at the above. If not, it is recommended that you learn digital electronics before getting in touch with microcontrollers, or you can directly read the following.

process

1. First, you need to know how to correctly light up a digital tube (static display).

The interior of the digital tube is composed of seven strip-shaped LEDs and a small dot LED, and the characters are formed according to the brightness of each tube. Common digital tubes have 10 pins. There are two common terminals, which can be divided into common cathode and common anode according to the wiring form of the internal LED. When in use, the common terminal of the common cathode digital tube is grounded, and the common terminal of the common anode digital tube is connected to the power supply. Refer to the figure below:

By giving each pin a high or low level, the on and off of the digital tube can be controlled. Let's take an example. Take the common cathode digital tube as an example. To make the digital tube display the number 0, as long as the six pins abcdef input a high level, the digital tube can display the number 0. At this time, the hexadecimal is 0011 1111 (dp, g, f, e, d, c, b, a) 0x3f. Send the above 0x3f to the 74HC573 latch, and the latch is sent to the digital tube, which lights up the digital tube. (From: https://blog.csdn.net/fanyuqa/article/details/47395333). This time, a common cathode is used.

2. We have learned how to light up a digital tube. Now we will introduce which of the 8 digital tubes to light up.

This requires the use of a 138 decoder. Among them, G1=vcc, G2A=G2B=0, and the purchased circuit has been connected by default. In the above circuit, ABC are P22, P23, and P24 respectively;

If P22=0, P23=0, P24=1 (0 represents low level, 1 represents high level), that is, 001, the corresponding truth table is 4. That is, the 4th digital tube is selected.

Once you know how to select and light up a digital tube, you can start writing programs.

#include "reg52.h"  

typedef unsigned int uint;   

typedef unsigned char uchar;

sbit LSA=P2^2;

sbit LSB=P2^3;

sbit LSC=P2^4;

uchar code smgduan[17]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,

0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71}; //Display the value of 0~F

void main()

{

LSA=0;

LSB=0;

LSC=0;

P0=smgduan[0];

}

The procedure is relatively simple, but there are two things to note.

1. You cannot directly set P2^2=0;

2. After code+array, the array cannot be changed. https://zhidao.baidu.com/question/121263820.html

Here is a video of a static digital tube, which is quite good: https://pan.baidu.com/s/1I7Gz55NCO_yqopAWOr07QA Password: 3p7r

3. Dynamic digital tubes are based on static digital tubes, but different digital tubes are lit each time. When the interval is very short, the human eye cannot distinguish them and will feel that they are all lit at the same time.

#include

typedef unsigned int uint;

typedef unsigned char uchar;

sbit LSA=P2^2;

sbit LSB=P2^3;

sbit LSC=P2^4;

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

void delay(uint num)

{

while(num--);

}

void display()

{

u8 i;

for(i=0;i<8;i++)

{

switch(i) //bit selection, select the digital tube to light up,

{

case(0):

LSA=0;LSB=0;LSC=0; break;//display bit 0

case(1):

LSA=1;LSB=0;LSC=0; break;//display the first bit

case(2):

LSA=0;LSB=1;LSC=0; break;//display the second digit

case(3):

LSA=1;LSB=1;LSC=0; break;//display the third bit

case(4):

LSA=0;LSB=0;LSC=1; break;//display the 4th bit

case(5):

LSA=1;LSB=0;LSC=1; break;//display the 5th bit

case(6):

LSA=0;LSB=1;LSC=1; break;//display the 6th bit

case(7):

LSA=1;LSB=1;LSC=1; break;//display the 7th bit

}

P0=out[i]; //Send segment code

delay(100); //Scan after a certain period of time

P0=0x00; //Blanking

}

}

void main()

{

while(1)

{

display(); 

}

}

Dynamic digital tube video tutorial: https://pan.baidu.com/s/1fLopEJvdCpouLziTaSWxmg Password: 7szd