// pwm.c
//
// Example program for bcm2835 library
// Shows how to use PWM to control GPIO pins
//
// After installing bcm2835, you can build this
// with something like:
// gcc -o pwm pwm.c -l bcm2835
// sudo ./pwm
//
// Or you can test it before installing with:
// gcc -o pwm -I ../../src ../../src/bcm2835.c pwm.c
// sudo ./pwm
//
// Author: Mike McCauley
// Copyright (C) 2013 Mike McCauley
// $Id: RF22.h,v 1.21 2012/05/30 01:51:25 mikem Exp $
#include <bcm2835.h>
#include <stdio.h>
// PWM output on RPi Plug P1 pin 12 (which is GPIO pin 18)
// in alt fun 5.
// Note that this is the _only_ PWM pin available on the RPi IO headers
#define PIN RPI_GPIO_P1_12
// and it is controlled by PWM channel 0
#define PWM_CHANNEL 0
// This controls the max range of the PWM signal
#define RANGE 64
int main(int argc, char **argv)
{
if (!bcm2835_init())
return 1;
// Set the output pin to Alt Fun 5, to allow PWM channel 0 to be output there
bcm2835_gpio_fsel(PIN, BCM2835_GPIO_FSEL_ALT5);
// Clock divider is set to 16.
// With a divider of 16 and a RANGE of 1024, in MARKSPACE mode,
// the pulse repetition frequency will be
// 1.2MHz/1024 = 1171.875Hz, suitable for driving a DC motor with PWM
bcm2835_pwm_set_clock(BCM2835_PWM_CLOCK_DIVIDER_2);
bcm2835_pwm_set_mode(PWM_CHANNEL, 1, 1);
bcm2835_pwm_set_range(PWM_CHANNEL, RANGE);
// Vary the PWM m/s ratio between 1/RANGE and (RANGE-1)/RANGE
int direction = 1;
int data = RANGE/4;
// while (1)
// {
// if (data == 1)
// direction = 1;
// else if (data == RANGE-1)
// direction = -1;
//data += direction;
bcm2835_pwm_set_data(PWM_CHANNEL, data);
// bcm2835_delay(50);
// }
bcm2835_close();
return 0;
}
