AT89C52 and 7-Segments Display Using C in Keil

 A typical digital display device is 7-Segments display. It’s very easy to program and interface to digital IC, or microcontroller for novice learner.

They come with different color and digit size. Common cathode and anode is a way to identify it. These two types are complement. Digital data inputs (7-Segments codes) to these two device type are different (complemented).

Voltage and current requirement for each segment are different depending on display’s digit-size. These parameters must be known as they are stated in device’s specification. Typically interfacing between digital controller and this device require a current limiting resistor for each segment.

AT89C52 typically supplied at +5V. So its digital output driving is +5V. We need to add a resistor between digital output pin of this controller and display.

Schematic diagram for program simulation

AT89C52 operates at 12MHz from external crystal oscillator. P1.0 is a digital input. Whenever it’s pressed it increase value of counter. Controller counts up to 16. P2 interfaces to a single common anode type 7-Segments display.

C program is written in Keil IDE for 8051 device. Coding is very simple.

#include <REG52.h>

sbit button=P1^0;

// common anode

unsigned char SSD[16]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x88,0x83,0xC6,0xA1,0x86,0x8E};

//unsigned char SSD[16]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6F,0x77,0x7C,0x39,0x5E,0x79,0x71};

unsigned char cnt=0;

void main(){

P2=0x00;

button=1;

cnt=0;

while(1){

if(button==0){

while(button==0);

cnt++;

if(cnt==16) cnt=0;

}

P2=SSD[cnt];

}

}

Click here to download this example package.