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#include <xc.h>
// PIC24FJ64GA002 Configuration Bit Settings
// 'C' source line config statements
// 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 measures the duty cycle (i.e., duration of a signal being 1) in
// terms of num cycles.
// INT0 pin has the external sig. T1 counts #cycles.
// Both programmed as interrupts.
volatile unsigned int overflow = 0;
volatile unsigned long int numCycles = 0; // duty cycle in terms of # TCY
volatile unsigned int high = 0, low = 0;
void __attribute__((__interrupt__,__auto_psv__)) _T1Interrupt(void)
{
IFS0bits.T1IF = 0;
overflow++;
}
void __attribute__((__interrupt__,__auto_psv__)) _INT0Interrupt(void)
{
_INT0IF = 0;
if (_INT0EP == 0){ // I was waiting for a rising edge
TMR1 = 0;
overflow = 0;
} else { // I was waiting for a falling edge
numCycles = TMR1 + 16000L * overflow;
// TMR1 = 0; // uncomment these two lines if you want the period
// overflow = 0; // and not just active duty cycle. also
// delete the if part, and the last line
// that changes polarity of INT0EP
}
_INT0EP = 1 - _INT0EP;
}
void setup(void)
{
CLKDIVbits.RCDIV = 0; // make 16MHz
// setup INT0 (RB7) pin as input
AD1PCFG = 0x9fff;
LATBbits.LATB7 = 1;
T1CON = 0;
PR1 = 15999;
TMR1 = 0;
T1CONbits.TON = 1;
IFS0bits.T1IF = 0;
//IPC0bits.T1IP = 4;
/* enable Timer 1 interrupt */
IEC0bits.T1IE = 1;
_INT0EP = 0;
_INT0IF = 0;
_INT0IE = 1;
}
int main(void)
{
setup();
int edge = 0;
while (1) {
}
}
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