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Light Timer with Interrupts

 
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jahan



Joined: 04 Apr 2005
Posts: 63

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Light Timer with Interrupts
PostPosted: Fri Sep 23, 2005 3:31 pm     Reply with quote
I'm writing a simple code to practice using my INT's and TIMERS.
3 Push Bottons are connected to RB0, RB1, RB2
RB0 = Start Timer (turn LED ON for 2 minutes and then turn it OFF)
RB1 = Turn LED ON (permenant)
RB2 = Turn LED OFF (if LED is ON even if on TIMER).

compiler: PCB,PCM,PCH=3.223

Code:
#include <18F452.h>
#device adc=8
#fuses NOWDT,WDT128,XT, NOPROTECT, NOOSCSEN, NOBROWNOUT, BORV20, NOPUT, \
       NOSTVREN, NODEBUG, NOLVP, NOWRT, NOWRTD, NOWRTB, NOWRTC, NOCPD, \
       NOCPB, NOEBTR, NOEBTRB
#use delay(clock=4000000)

#define ON  1
#define OFF 0
#define INTS_PER_SECOND 25        // (4,000,000/(4*16*250*10)) = 25

// Global Variables
int8 seconds;      // A running seconds counter
int8 int_count;    // Number of interrupts left before a second has elapsed

void Lights(int stat) {
   if (stat == ON)
      output_high(PIN_A0);
   else
      output_low(PIN_A0);
}

#int_TIMER2
void TIMER2_isr() {
    // timer 2 overflows (250->0), which is apx 25 times/Sec
    if(--int_count == 0) {
      ++seconds;
      if (seconds == 120) {
         Lights(OFF);
         disable_interrupts(INT_TIMER2);
      } else {
         int_count = INTS_PER_SECOND;
      }
    }
}

#int_EXT
EXT_isr() { // Timer switch
   Lights(ON);
   int_count = INTS_PER_SECOND;
   seconds = 0;
   enable_interrupts(INT_TIMER2);
}

#int_EXT1
EXT1_isr() { // Light ON   
   disable_interrupts(INT_TIMER2);
   Lights(ON);
}

#int_EXT2
EXT2_isr() { // Light OFF
   disable_interrupts(INT_TIMER2);
   Lights(OFF);
}

void main() {
   int_count = INTS_PER_SECOND;
   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_psp(PSP_DISABLED);
   setup_wdt(WDT_OFF);
   setup_timer_2(T2_DIV_BY_16, 250, 10);
   set_timer2(0);
   setup_ccp1(CCP_OFF);
   enable_interrupts(INT_EXT);
   enable_interrupts(INT_EXT1);
   enable_interrupts(INT_EXT2);
   enable_interrupts(GLOBAL);
   while (TRUE) {
      ;
   }
}


Please give me feed back as if this is the best way of doing this using INT and TMR2?

Thankx in advance
treitmey



Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA

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PostPosted: Mon Sep 26, 2005 8:10 am     Reply with quote
1)I would not pass an int8 into light() function when a int1 would do
2)in an isr just set a flag or buffer data. Dont go calling all sorts of funtions. KEEP IT SHORT
3)in general if a function[[light()]] is that simple, you should do it inline to save a calling level.
4)So if you move the bulk of the code out of the isr then you would have a loop at the end of main that would do something like

- - - -I don't know if this will work, but i thnk you'll get my meaning.- - - -
Code:
#include <18F452.h>
#fuses NOWDT,WDT128,XT, NOPROTECT, NOOSCSEN, NOBROWNOUT, BORV20, NOPUT, \
NOSTVREN, NODEBUG, NOLVP, NOWRT, NOWRTD, NOWRTB, NOWRTC, NOCPD, \
NOCPB, NOEBTR, NOEBTRB
#use delay(clock=16000000)
//#use delay(clock=4000000)

#define ON  1
#define OFF 0
#define INTS_PER_SECOND 25        // (4,000,000/(4*16*250*10)) = 25
// Global Variables
int8 seconds;      // A running seconds counter
int8 int_count;    // Number of interrupts left before a second has elapsed
int1 light_on,timer_on;    // Number of interrupts left before a second has elapsed

#int_TIMER2
void TIMER2_isr() {
  // timer 2 overflows (250->0), which is apx 25 times/Sec
  if(--int_count == 0) {
    ++seconds;
  }
}

#int_EXT
EXT_isr() { // Timer switch
  timer_on=TRUE;
}

#int_EXT1
EXT1_isr() { // Light ON
  light_on=TRUE;
}

#int_EXT2
EXT2_isr() { // Light OFF
  light_on=FALSE;
}

void main() {
  int_count = INTS_PER_SECOND;
  setup_adc_ports(NO_ANALOGS);
  setup_adc(ADC_OFF);
  setup_psp(PSP_DISABLED);
  setup_wdt(WDT_OFF);
  setup_timer_2(T2_DIV_BY_16, 250, 10);
  set_timer2(0);
  setup_ccp1(CCP_OFF);
  enable_interrupts(INT_EXT);
  enable_interrupts(INT_EXT1);
  enable_interrupts(INT_EXT2);
  enable_interrupts(GLOBAL);
  while (TRUE) {
    if(timer_on)
    {
      output_high(PIN_A0);
      int_count = INTS_PER_SECOND;
      seconds = 0;
      enable_interrupts(INT_TIMER2);
      timer_on=false;
    }
    if(light_on)
    {
      output_high(PIN_A0);
    }
    if(!light_on)
    {
      output_low(PIN_A0);
    }
    if (seconds == 120)
    {
      light_on=false;
      disable_interrupts(INT_TIMER2);
    }
    else
    {
      int_count = INTS_PER_SECOND;
    }
  }
}
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