Raspberry Pi 3 PWM Led Pulse

Question

I want to control LED diod with PWM using bcm2835.h and pure C langueage. My code does not work. What am I missing?

I have tried "gpio" console command and it works fine, so I know that led is connected to the right ports. I can turn it on using console command:

gpio pwm 1 1024

My code:

#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 1024


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_16);

    bcm2835_pwm_set_mode(PWM_CHANNEL, 1, 1);

    bcm2835_pwm_set_range(PWM_CHANNEL, RANGE);

    while(1)
    {
        bcm2835_pwm_set_data(PWM_CHANNEL, 1024);
        bcm2835_delay(10);
    }


    bcm2835_close();
    return 0;
}

I expect that my LED will turn on.

Answer 1

This is stupid, but after checking the math, code, wiring I discovered that app needs to be run with root privileges to have on-board access to the pins. It works fine. Topic can be closed.