STC89C52 microcontroller digital tube static display

Digital tube display principle

Digital tubes are divided into common cathode and common anode according to different internal connections. There are 8 LEDs inside the eight-segment digital tube. If you want to display a specific font, you only need to control the corresponding LED to light up and the other LEDs to turn off.

Static and dynamic display

Static display:

There are two working modes of LED displays: static display mode and dynamic display mode. The characteristic of static display is that the segment selection of each digital tube must be connected to a 9-bit data line to maintain the displayed glyph code. After the glyph code is sent once, the displayed glyph can be maintained until a new glyph code is sent.

Disadvantages: More IO ports are used.

dynamic display

The characteristic of dynamic display is that the segment selection lines of all digital tubes are connected in parallel, and the bit selection lines control which digital tube is effective. The selected digital tube adopts dynamic scanning display. The so-called dynamic scanning display is to send glyph codes and corresponding bit selections to each digital tube in turn. It uses the afterglow of the luminescent tube and the persistence of human vision to make people feel as if all the digital tubes are displaying at the same time.

How the 74HC573 latch works

Chip document query website: https://www.alldatasheet.com/

The role of pull-up resistors

Pull-up is to clamp the uncertain signal to a high level through a resistor, and the resistor also acts as a current limiter. In the same way, the lower level also clamps the uncertain signal at a low level through a resistor.

When the P0 port is used as an input or output port, it is in open-drain mode after power-on reset. There is no pull-up resistor inside the P0 port, so the I/0 port must be connected to an external pull-up resistor of 10K-4.7K.

Light up the single digit "1"

#include

#include

#define uint unsigned int

#define uchar unsigned char

sbit DU = P2^6;//digital tube segment selection

sbit WE = P2^7;//Nigital tube segment selection

void main(){ // The main function itself will loop

WE = 1; //Open bit select latch

P0 = 0XFE; // 1111 1110 strobe the first digital tube

// P0 = 0X00; // 0000 0000 means strobing all digital tubes

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = 0X06; // 0000 0110 displays "1"

DU = 0; //Latch segment selection data

while(1){

   // P0 = 0X01; // When the value in the latch is locked, the value of the digital tube cannot be modified directly. You need to open the bit selection latch to modify it.

}

}

Light up the two-digit number "2"

#include

#include

#define uint unsigned int

#define uchar unsigned char

sbit DU = P2^6;//digital tube segment selection

sbit WE = P2^7;//Nigital tube segment selection

void main(){ // The main function itself will loop

WE = 1; //Open bit select latch

P0 = 0XFC; // 1111 1100 strobe the first and second digital tubes

// P0 = 0X00; // 0000 0000 means strobing all digital tubes

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = 0X5B; // 0101 1011 displays "2"

DU = 0; //Latch segment selection data

while(1){

   // P0 = 0X01; // When the value in the latch is locked, the value of the digital tube cannot be modified directly. The latch needs to be opened to modify it.

}

}

Light up the three-digit number "3"

#include

#include

#define uint unsigned int

#define uchar unsigned char

sbit DU = P2^6;//digital tube segment selection

sbit WE = P2^7;//Nigital tube segment selection

void main(){ // The main function itself will loop

WE = 1; //Open bit select latch

P0 = 0XF8; // 1111 1000 selects the first, second and third digital tubes

// P0 = 0X00; // 0000 0000 means strobing all digital tubes

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = 0X4F; // 0100 1111 displays "3"

DU = 0; //Latch segment selection data

while(1){

   // P0 = 0X01; // When the value in the latch is locked, the value of the digital tube cannot be modified directly. The latch needs to be opened to modify it.

}

}

Light up the last digit "8" of the digital tube

#include

#include

#define uint unsigned int

#define uchar unsigned char

sbit DU = P2^6;//digital tube segment selection

sbit WE = P2^7;//Nigital tube segment selection

void main(){ // The main function itself will loop

WE = 1; //Open bit select latch

P0 = 0X7F; // 1111 1000 strobes the eighth digital tube

// P0 = 0X00; // 0000 0000 means strobing all digital tubes

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = 0X7F; // 0111 1111 displays "8"

DU = 0; //Latch segment selection data

while(1){

   // P0 = 0X01; // When the value in the latch is locked, the value of the digital tube cannot be modified directly. The latch needs to be opened to modify it.

}

}

Make the third (from left to right) digital tube display the number 6

#include

#include

#define uint unsigned int

#define uchar unsigned char

sbit DU = P2^6;//digital tube segment selection

sbit WE = P2^7;//Nigital tube segment selection

void main(){ // The main function itself will loop

P0 = 0X00; //Clear broken code

WE = 1; //Open bit select latch

P0 = 0X03; // 0000 0011 Strobe the 3rd, 4th, 5th, 6th, 7th and 8th digital tubes

// P0 = 0X00; // 0000 0000 means strobing all digital tubes

WE = 0; //Latch bit selection data

DU = 1; //Open segment selection latch

P0 = 0X7D; // The corresponding digital tube letter acdefg of 0111 1101 displays "6"

DU = 0; //Latch segment selection data

}