7 segment display

[mircea2012]

Hy
I have a HP488 development board with PIC16F88 mcu.
I try to make a program who count from 0 to 9999 with a delay using Timer TMR0.

My problem is I am not able to make this work.
The program must do the next tasks : count from 0 to 9 --> digit 3 and when it reaches 9 must enable digit 2.
If the count it reaches to 99 must enable digit 3 and so on.
I know how to enable the digits, i read it elctrical drawings. I failed when I try to implement it.
Can somebody give me some tips.
Look at my code.
Thank you.

#include <system.h>
#pragma CLOCK_FREQ 8000000
#pragma DATA _CONFIG, _CP_OFF & _PWRTE_OFF & _WDT_OFF & _HS_OSC & _LVP_OFF

void setup_hardware(void)
{
trisb = 0x00;
trisa = 0xf0;
intcon = 0b10100000;
option_reg = 0b00000111;
}

unsigned char patterns[10] = {0xc0, 0xf9, 0xa4, 0xb0, 0x99, 0x92, 0x83, 0xf8, 0x80, 0x98};

unsigned char led_counter = 0;

unsigned char led_patterns[4] = {0x08, 0x0C, 0x0E, 0x0F};

unsigned char led = 0;

void display(void)
{
porta = 0;
portb = patterns[led_counter++];
porta = led_patterns[led];
if (led_counter > 9)
led_counter = 0;
}

void display_digit(unsigned char digit, unsigned char pos)
{
led_patterns[pos] = patterns[digit] ;
}

unsigned char counter = 0;

void interrupt(void)
{
if(intcon & 0x04)
{
clear_bit( intcon, 2 );
counter++;
if(counter == 15)
{
counter = 0;
display();
}
}
}

void main ( void )
{
setup_hardware() ;
while(1)
{

}
}

[Benj]

Hello,

The 7-seg display needs to be multiplexed constantly to allow you to display more then a single digit.

Therefore you might be better off using 2 timers. 1 to increment the count which is displayed and the other to drive the display. You could get away with one timer and simply doing the multiplexing in a while loop as part of main.

Each segment needs to be enabled in turn so you would do something like this.

output character 0 to portb
enable 7-seg 0
wait a short delay - 5ms works well
disable 7-seg 0

output character 1 to portb
enable 7-seg 1
wait a short delay - 5ms works well
disable 7-seg 1

output character 2 to portb
enable 7-seg 2
wait a short delay - 5ms works well
disable 7-seg 2

output character 3 to portb
enable 7-seg 3
wait a short delay - 5ms works well
disable 7-seg 3