Code

SAM D21 Xplained Pro.

#define PWM_MODULE      EXT1_PWM_MODULE

#define PWM_OUT_PIN     EXT1_PWM_0_PIN

#define PWM_OUT_MUX     EXT1_PWM_0_MUX

SAM D20 Xplained Pro.

#define PWM_MODULE      EXT1_PWM_MODULE

#define PWM_OUT_PIN     EXT1_PWM_0_PIN

#define PWM_OUT_MUX     EXT1_PWM_0_MUX

Add to the main application source file, outside of any functions:

struct tc_module tc_instance;

Copy-paste the following setup code to your user application:

void configure_tc(void)
{
    struct tc_config config_tc;
    tc_get_config_defaults(&config_tc);

    config_tc.counter_size    = TC_COUNTER_SIZE_16BIT;
    config_tc.wave_generation = TC_WAVE_GENERATION_MATCH_FREQ;
    config_tc.counter_16_bit.compare_capture_channel[0] = 4000;

    config_tc.pwm_channel[0].enabled = true;
    config_tc.pwm_channel[0].pin_out = PWM_OUT_PIN;
    config_tc.pwm_channel[0].pin_mux = PWM_OUT_MUX;

    tc_init(&tc_instance, PWM_MODULE, &config_tc);

    tc_enable(&tc_instance);
}

Add to user application initialization (typically the start of main()):

configure_tc();