// Author: Vivek Sinha
// (c) Vivek Sinha 2013
//
#include <htc.h>
#include <pic12f675.h>
// Hardware config and 4MHz internal clock
__CONFIG( FOSC_INTRCIO & WDTE_OFF & PWRTE_ON & MCLRE_ON & CP_OFF & CPD_OFF & BOREN_OFF );
#define _XTAL_FREQ 4000000 // Internal clock at 4 MHz
#define LED GPIO0 // LED on GP0 pin 7
// Variables for brightness level
int brightness=1;
int fadeamount=1;
// Initialize function. LED connected from GP0 (pin 7) with a 1K Ohm resistance to ground.
void initialize(void)
{
ANSEL = 0;
CMCON = 7;
TRISIO = 0;
GPIO = 0;
}
// Custom microsecond Delay function
delay_us(unsigned int microseconds)
{
while(microseconds > 0)
{
__delay_us(1);
microseconds--;
}
}
// Software PWM code
void pwm()
{
// Switch On or Off the LED with the appropriate delay
GPIO0 = 1;
delay_us(256-brightness);
GPIO0 = 0;
delay_us(brightness);
// Change brightness and when brightness becomes min or max reset.
brightness = brightness + fadeamount;
if(brightness ==0 || brightness == 256)
{
fadeamount = -fadeamount;
}
}
// Main function
void main()
{
initialize();
while(1) // Infinite loop
{
pwm(); // call PWM function
}
}
