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PIC timer

 
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Noobie
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PIC timer
PostPosted: Wed Mar 11, 2009 2:41 pm     Reply with quote
I'm new in PIC programming and i've some question about PIC16F876A. Here are my Question: How long is the maximum delay can the PIC uC do? If I'd like to activate a sensor after 3 days (72Hrs) I turn ON the PIC, what should I use for such long delay?

Any examples can be referred?

Can someone help me on this matter? I need to solve this doubt for my Final Year Project.

Thank you.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Mar 11, 2009 3:13 pm     Reply with quote
If the only thing you want to do, after power-up of the PIC, is to wait
for 3 days, then you can just call delay_ms() in a loop.

This will give a one minute delay:
Code:
delay_ms(60000);

Then just create a for(;;) loop that calls it the required number of times.

A tip regarding the loop counter value:
Remember that in CCS, an 'int' is an unsigned 8-bit integer, and can take
values from 0 to 255. If you want a larger number, you need to use
declare it as 'int16' (0 to 65535) or 'int32'.
necati



Joined: 12 Sep 2003
Posts: 37
Location: istanbul

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PostPosted: Wed Mar 11, 2009 3:21 pm     Reply with quote
Code:
#include <16f876a.h>
#fuses  XT, NOPROTECT,PUT, NOWDT,BROWNOUT
#use    delay(clock=4000000)
#BYTE   PORT_A=0X05
#BYTE   PORT_B=0X06
#BYTE   PORT_C=0X07
/***entegreterbiyecisi@yahoo.com***/
// LCD STUFF
#define LCD_RS      PIN_b6
#define LCD_EN      PIN_b5
#define LCD_D4      PIN_b4
#define LCD_D5      PIN_b3
#define LCD_D6      PIN_b2
#define LCD_D7      PIN_b1
#define FIRST_LINE  0x00
#define SECOND_LINE 0x40
#define CLEAR_DISP  0x01
#define CURS_ON     0x0e
#define CURS_OFF    0x0c
/***entegreterbiyecisi@yahoo.com***/
#use fast_io ( a )
#use fast_io ( b )
#use fast_io ( c )
/***entegreterbiyecisi@yahoo.com***///lcd
void LCD_Init        ( void );
void LCD_SetPosition ( unsigned int cX );
void LCD_PutChar     ( unsigned int cX );
void LCD_PutCmd      ( unsigned int cX );
void LCD_PulseEnable ( void );
void LCD_SetData     ( unsigned int cX );
/***entegreterbiyecisi@yahoo.com***/
int16 clock =400;
int8 hours=0,minutes=0,seconds=0;
int1 yz=0;
///////////////////////////////////////////

///////////////////////////////////////////
#int_TIMER1
void TIMER1() {
clock -=25 ;
///////////////////////////
if(clock <25 ) {seconds++;clock +=400;yz=1;    //sec   1 artır  400
if(seconds == 60) {minutes++;seconds = 0; //60    puls ta min  1 artır
if(minutes == 60) {hours++;minutes = 0;   //60    puls ta hour 1 artır
}}}}
/*************************entegreterbiyecisi@yahoo.com******************************/
void main(void){

      setup_adc_ports(no_analogs);
      SET_TRIS_A   (0b11111111);
      SET_TRIS_B   (0b10000001);
      SET_TRIS_C   (0b10000000);
      setup_timer_1(t1_internal|t1_div_by_1);
      enable_interrupts(int_timer1);
      enable_interrupts(global);     
      PORT_A=0;
      PORT_B=0;
      PORT_C=0;
      port_b_pullups(0b10000000);
      lcd_init();
      //LCD_PutCmd(CURS_ON);
      LCD_PutCmd(CLEAR_DISP);
      output_high (pin_c3);
      delay_ms (100);
///////////////////////////////////////////////
   while(true){
          if(yz==1){LCD_SetPosition (second_LINE+0);
                  printf(lcd_putchar,"\%02d:%02d:%02d",hours,minutes,seconds);
                  output_toggle(PIN_c2);
                  yz=0;}
                  if(hours==72){output_low (pin_c3);}
              }}
/***entegreterbiyecisi@yahoo.com***/ //lcd basla
void LCD_Init ( void ){
    LCD_SetData ( 0x00 );
    output_low ( LCD_RS );
    LCD_SetData ( 0x03 );
    LCD_PulseEnable();
    LCD_PulseEnable();
    LCD_PulseEnable();
    LCD_SetData ( 0x02 );
    LCD_PulseEnable();   
    LCD_PutCmd ( 0x2C );   
    LCD_PutCmd ( 0x0C );   
    LCD_PutCmd ( 0x01 );   
    LCD_PutCmd ( 0x06 );   
    }
/***entegreterbiyecisi@yahoo.com***/
void LCD_SetPosition ( unsigned int cX )
    {
    LCD_SetData ( swap ( cX ) | 0x08 );
    LCD_PulseEnable();
    LCD_SetData ( swap ( cX ) );
    LCD_PulseEnable();
    }
/***entegreterbiyecisi@yahoo.com***/
void LCD_PutChar ( unsigned int cX )
    {
    output_high ( LCD_RS );
    LCD_SetData ( swap ( cX ) );
    LCD_PulseEnable();
    LCD_SetData ( swap ( cX ) ); 
    LCD_PulseEnable();
    output_low ( LCD_RS );
    }
/***entegreterbiyecisi@yahoo.com***/
void LCD_PutCmd ( unsigned int cX )
    {
    LCD_SetData ( swap ( cX ) );   
    LCD_PulseEnable();
    LCD_SetData ( swap ( cX ) );     
    LCD_PulseEnable();
    }
/***entegreterbiyecisi@yahoo.com***/
void LCD_PulseEnable ( void )
    {
    output_high ( LCD_EN );
    delay_us ( 100 );
    output_low ( LCD_EN );
    delay_ms ( 5 );
    }
/***entegreterbiyecisi@yahoo.com***/
void LCD_SetData ( unsigned int cX )
    {
    output_bit ( LCD_D4, cX & 0x01 );
    output_bit ( LCD_D5, cX & 0x02 );
    output_bit ( LCD_D6, cX & 0x04 );
    output_bit ( LCD_D7, cX & 0x08 );
    }
/***entegreterbiyecisi@yahoo.com***/ //lcd son
Noobie
Guest
PostPosted: Thu Mar 12, 2009 10:02 am     Reply with quote
Thanks for PCM programmer, i manage to have few minutes waiting, now i'm running the board and test for hrs and days experiment. thank you for info~ ^^

Thanks to necati for providing the code, however, i do not need to display my counter... But i'll consider to do it for my enhancement if i have extra time.. ^^
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