/******* IntProg2.c ************
 *
 * Use Fosc = 4 MHz for Fcpu = Fosc/4 = 1 MHz.
 * Timer1 and Timer3 are both clocked by the internal clock.
 *
 ******* Program hierarchy *****
 *
 * main
 *    Initial
 *
 * LoPriISR
 *
 * HiPriISR
 *
 *******************************
 */

#include <p18f4321.h>           // Define PIC18LF4321 registers and bits

/*******************************
 * Configuration selections
 *******************************
 */
#pragma config OSC = INTIO1     // Use internal osc, RA6=Fosc/4, RA7=I/O
#pragma config PWRT = ON        // Enable power-up delay
#pragma config LVP = OFF        // Disable low-voltage programming
#pragma config WDT = OFF        // Disable watchdog timer initially
#pragma config MCLRE = ON       // Enable master clear pin
#pragma config PBADEN = DIG     // PORTB<4:0> = digital
#pragma config CCP2MX = RB3     // Connect CCP2 internally to RB3 pin
#pragma config BOR = SOFT       // Brown-out reset controlled by software
#pragma config BORV = 3         // Brown-out voltage set for 2.0V, nominal
#pragma config LPT1OSC = OFF    // Deselect low-power Timer1 oscillator

/*******************************
 * Global variables
 *******************************
 */
unsigned char i;                // Index into strings
unsigned int DELAY;             // Sixteen-bit counter for obtaining a delay

/*******************************
 * Function prototypes
 *******************************
 */
void Initial(void);
void HiPriISR(void);
void HPISRhandler(void);
void LoPriISR(void);
void LPISRhandler(void);

/*******************************
 * Macros
 *******************************
 */
#define Delay(x) DELAY = x; while(--DELAY){ Nop(); Nop(); }

/*******************************
 * Interrupt vectors
 *******************************
 */
// For high priority interrupts:
#pragma code high_vector=0x08
void interrupt_at_high_vector(void)
{
  _asm GOTO HiPriISR _endasm
}
#pragma code
#pragma interrupt HiPriISR

// For low priority interrupts:
#pragma code low_vector=0x18
void interrupt_at_low_vector(void)
{
  _asm GOTO LoPriISR _endasm
}
#pragma code
#pragma interruptlow LoPriISR

/*******************************
 * HiPriISR
 *
 * Clear flag, toggle RB1 and return.
 *******************************
 */
void HiPriISR()
{
   HPISRhandler();
}

/*******************************
 *  LPISRhandler
 *******************************
 */
void HPISRhandler()
{
   TMR3H = 0xFF;
   PIR2bits.TMR3IF = 0;         // Clear interrupt flag
   PORTBbits.RB1 ^= 1;          // Toggle pin
}

/*******************************
 * LoPriISR
 *
 * Clear flag, toggle RB0 and return.
 *******************************
 */
void LoPriISR()
{
   LPISRhandler();
}

/*******************************
 *  LPISRhandler
 *******************************
 */
void LPISRhandler()
{
   TMR1H = 0xFF;
   PIR1bits.TMR1IF = 0;         // Clear interrupt flag
   PORTBbits.RB0 ^= 1;          // Toggle pin
}

/////// Main program //////////////////////////////////////////////////////////

/*******************************
 * main
 *******************************
 */
void main()
{
   Initial();                   // Initialize everything
   while (1)
   {
      PORTCbits.RC2 = 1;        // Set pin high
      Delay(14);
      PORTCbits.RC2 = 0;
      Delay(20);
   }
}

/*******************************
 * Initial
 *
 * This function performs all initializations of variables and registers.
 *******************************
 */
void Initial()
{
   OSCCON = 0b01100010;         // Use Fosc = 4 MHz (Fcpu = 1 MHz)
   ADCON1 = 0b00001011;         // RA0,RA1,RA2,RA3 pins analog; others digital
   TRISA = 0b00001111;          // Set I/O for PORTA
   TRISB = 0b01000100;          // Set I/O for PORTB
   TRISC = 0b10000000;          // Set I/O for PORTC
   TRISD = 0b10000000;          // Set I/O for PORTD
   TRISE = 0b00000010;          // Set I/O for PORTE
   PORTA = 0;                   // Set initial state for all outputs low
   PORTB = 0;
   PORTC = 0;
   PORTD = 0b00100000;          // except RD5 that drives LCD interrupt
   PORTE = 0;
   Delay(50000);                // Pause for 0.5 second to make use of brownout
                                // reset on any power switch contact bounce
                                // and to let LCD controller initialize before
                                // any display strings are sent to it.
   RCONbits.SBOREN = 0;         // After this delay, disable brown-out reset
   T1CON = 0b01001101;          // Timer1 - loop time via low-pri interrupts  Use internal clock
   T3CON = 0b00000101;          // Timer3 - step motor via hi-pri interrupts
   TMR1H = 0xFE;                // Set Timer1 to be 10 ms away from
   TMR1L = 0xB9;                // next roll over (65536 + 1 - 328 = 0xFEB9)
   TMR3H = 0xFF;                // Set Timer3 to be 4 ms away from
   TMR3L = 0xAE;                // next roll over (65536 + 1 - 131 = 0xFF7E)
//   PIE1bits.TMR1IE = 1;         // Enable local interrupt source
   PIE2bits.TMR3IE = 1;         // Enable local interrupt source
   IPR1bits.TMR1IP = 0;         // Use Timer1 for low-priority interrupts
   IPR2bits.TMR3IP = 1;         // Use Timer3 for hi-priority interrupts
   RCONbits.IPEN = 1;           // Enable high/low priority interrupt feature
   INTCONbits.GIEL = 1;         // Global low-priority interrupt enable
   INTCONbits.GIEH = 1;         // Enable both high and low interrupts
}