jimmyvarghese143
New Member
Code:
]#include <pic.h>
/*
* Interrupt demo for PIC; wait for button press on RB0/INT,
* turn on a relay on another port bit for a period of time.
* For simplicity here, literal constants are used, usually these
* should be calculated with compile-time arithmetic.
*/
#define RELAY RB4 // use this bit to drive relay
static unsigned int relay_timer; // timer value for relay driver
void main(void)
{
/* setup stuff */
RELAY = 1; // ensure relay is off before enabling output
TRISB = 0x03; // Port B bits 7 and 6 are output
OPTION = 0b00000111;
TRISB = 0b00000011;
RBPU = 0; // Use internal pullups
T0IE = 1; // Enable interrupt on TMR0 overflow
INTEDG = 1; // falling edge trigger the interrupt
INTE = 1; // enable the external interrupt
GIE = 1; // Global interrupt enable
for(;;)
{
CLRWDT(); // Idly kick the dog
}
}
static void interrupt
isr(void) .
{
if(T0IF)
{ // timer interrupt
PORTB ^= 4;
if(relay_timer)
{ // is the relay timer running?
relay_timer--; // decrement it
PORTB |= 8;
}
else
{
RELAY = 1; // turn the relay off
PORTB &= ~8; // toggle a bit to say we're alive
}
T0IF = 0; // clear the interrupt flag
}
if(INTF)
{ // did we see a button press?
RELAY = 0; // turn the relay on
relay_timer = 16; // start the timer - 16 timeouts ~ 1 second
INTF = 0; // clear the interrupt
}
}
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