#include <p24Fxxxx.h>

#include <xc.h>

// PIC24FJ64GA002 Configuration Bit Settings

// 'C' source line config statements

#include <xc.h>

// CONFIG2
#pragma config POSCMOD = NONE           // Primary Oscillator Select (Primary oscillator disabled)
#pragma config I2C1SEL = PRI            // I2C1 Pin Location Select (Use default SCL1/SDA1 pins)
#pragma config IOL1WAY = OFF            // IOLOCK Protection (IOLOCK may be changed via unlocking seq)
#pragma config OSCIOFNC = OFF           // Primary Oscillator Output Function (OSC2/CLKO/RC15 functions as CLKO (FOSC/2))
#pragma config FCKSM = CSECME           // Clock Switching and Monitor (Clock switching is enabled, Fail-Safe Clock Monitor is enabled)
#pragma config FNOSC = FRCPLL           // Oscillator Select (Fast RC Oscillator with PLL module (FRCPLL))
#pragma config SOSCSEL = SOSC           // Sec Oscillator Select (Default Secondary Oscillator (SOSC))
#pragma config WUTSEL = LEG             // Wake-up timer Select (Legacy Wake-up Timer)
#pragma config IESO = ON                // Internal External Switch Over Mode (IESO mode (Two-Speed Start-up) enabled)

// CONFIG1
#pragma config WDTPS = PS32768          // Watchdog Timer Postscaler (1:32,768)
#pragma config FWPSA = PR128            // WDT Prescaler (Prescaler ratio of 1:128)
#pragma config WINDIS = ON              // Watchdog Timer Window (Standard Watchdog Timer enabled,(Windowed-mode is disabled))
#pragma config FWDTEN = OFF             // Watchdog Timer Enable (Watchdog Timer is disabled)
#pragma config ICS = PGx1               // Comm Channel Select (Emulator EMUC1/EMUD1 pins are shared with PGC1/PGD1)
#pragma config GWRP = OFF               // General Code Segment Write Protect (Writes to program memory are allowed)
#pragma config GCP = OFF                // General Code Segment Code Protect (Code protection is disabled)
#pragma config JTAGEN = OFF             // JTAG Port Enable (JTAG port is disabled)

// This program is used in explaining the concept of range vs.
// resolution. We can use the stimulous to create an input signal
// with a given period and measure its period using T1CK and the
// TGATE capability.

void setup(void)
{
    CLKDIVbits.RCDIV = 0; // make 16MHz

    // setup T1 to count the number of pulses on T1CK
    T1CON = 0;
    PR1 = 60000;    // do not overflow soon.
    T1CONbits.TCKPS = 1;  // pre=8
    TMR1 = 0;           // doesn't matter. we will reset on pos edge on INT0
    T1CONbits.TON = 1;
    IFS0bits.T1IF = 0;  // doesn't matter, we never look at it.
}


int main(void)
{
    int dutyCycle;
    setup();

    while (1) {
        _INT0IF = 0;
        _INT0EP = 0;    // int on positive edge
        while (_INT0IF==0); // wait for the first positive edge
        _INT0IF = 0;
        TMR1 = 0;           // start the timer to count # cycles
                            //   for which the signal is 1
        _INT0EP = 1;    // int on positive edge
        while (_INT0IF==0); // wait for the first positive edge
        _INT0IF = 0;
        dutyCycle = TMR1;
    }
}