/*

* File: main.c

* Author: Nolan

* Chip: PIC16F1829

* Created on April 14, 2016

* - Pressing a pull-down button on RB5 triggers an interrupt

* - TMR0 is setup in the interrupt service routine (ISR) to delay re-enabling the RB5 interrupt

* - When TMR0 overflows 0xFF, the TMR0IF is triggered

*/

#include <xc.h>

// Insert CONFIG code here

#define LED RA5

#define LED_TRIS TRISA5

#define BUTTON_RELEASED RB5

void led_on(){

LED_TRIS = 0;

LED = 1;

}

void led_off(){

LED_TRIS = 0;

LED = 0;

}

void toggle_led(){

if(LED){

led_off();

}

else {

led_on();

}

}

// interrupt service routine

// executed when an interrupt occurs

void interrupt ISR(void){

if(IOCIE && IOCIF && IOCBF5){

toggle_led();

while(!BUTTON_RELEASED);

TMR0 = 0x00;

OPTION_REG = 0b00000011;

TMR0IF = 0;

TMR0IE = 1;

IOCBF5 = 0;

IOCIF = 0;

IOCIE = 0;

}

if(TMR0IE && TMR0IF){

IOCBF5 = 0;

IOCIF = 0;

IOCIE = 1;

TMR0IF = 0;

TMR0IE = 0;

}

PEIE = 1;

GIE = 1;

return;

}

void reset_interrupts(void){

// disable all interrupts

GIE = 0;

PEIE = 0;

// clear all interrupt flags

INTCON = 0;

PIR1 = 0;

PIR2 = 0;

PIR3 = 0;

PIR4 = 0;

// disable all interrupts

PIE1 = 0;

PIE2 = 0;

PIE3 = 0;

PIE4 = 0;

// all interrupts are cleared and disabled

// setup needed interrupts in other functions

return;

}

void configure_tmr0(void){

TMR0 = 0x00;

TMR0IF = 0;

TMR0IE = 1;

PEIE = 1;

GIE = 1;

OPTION_REG = 0b00000111; //without Prescaler, LED will blink too fast

return;

}

void configure_button(){

// clear all IOC flags and disable all IOC

IOCAF = 0;

IOCAN = 0;

IOCAP = 0;

IOCBF = 0;

IOCBN = 0;

IOCBP = 0;

// set up RB5 IOC

ANSB5 = 0;

TRISB5 = 1;

WPUB5 = 1;

INLVLB5 = 1;

IOCBP5 = 0;

IOCBN5 = 1;

IOCBF5 = 0;

IOCIF = 0;

IOCIE = 1;

PEIE = 1;

GIE = 1;

return;

}

void main(void) {

reset_interrupts();

configure_tmr0();

configure_button();

while(1);

return;

}