I am having problem with the PWM driver.
I need PWM for a very simple application where I need it to drive a buzzer with a series of 50% duty cycle pulses.
Trying to set it up gives me problems with the documentation level, so I am trying to guess the functions of the pwm and experiment with the values.
I initialize with the following:
#define SCALED_RANGE 366 // 1 MHz scaled to 2.730 Hz
#define DUTY_CYCLE_50 (SCALED_RANGE/2)
void Initialize(void)
{
nrfx_pwm_config_t const config0 = //NRFX_PWM_DEFAULT_CONFIG;
{
.output_pins = { BUZZER_PIN, \
NRFX_PWM_PIN_NOT_USED, \
NRFX_PWM_PIN_NOT_USED, \
NRFX_PWM_PIN_NOT_USED }, \
.irq_priority = NRFX_PWM_DEFAULT_CONFIG_IRQ_PRIORITY, \
.base_clock = (nrf_pwm_clk_t)NRFX_PWM_DEFAULT_CONFIG_BASE_CLOCK, \
.count_mode = (nrf_pwm_mode_t)NRFX_PWM_DEFAULT_CONFIG_COUNT_MODE, \
.top_value = SCALED_RANGE, \
.load_mode = NRF_PWM_LOAD_COMMON, // (nrf_pwm_dec_load_t)NRFX_PWM_DEFAULT_CONFIG_LOAD_MODE, \
.step_mode = (nrf_pwm_dec_step_t)NRFX_PWM_DEFAULT_CONFIG_STEP_MODE
};
// Init PWM without error handler
// returns nrfx_err_t
APP_ERROR_CHECK(nrfx_pwm_init(&m_pwm0, &config0, PwmEventHandler));
}
But when using it, I do not understand repeat and loop counts values.
First if I set the repeats to 100
nrf_pwm_values_individual_t seq_values[] = {DUTY_CYCLE_50, DUTY_CYCLE_50, DUTY_CYCLE_50, DUTY_CYCLE_50};
nrf_pwm_sequence_t const seq =
{
.values.p_individual = seq_values,
.length = 1, //NRF_PWM_VALUES_LENGTH(seq_values),
.repeats = 100,
.end_delay = 0
};
And call
nrfx_pwm_simple_playback(&m_pwm0, &seq, 1, NRFX_PWM_FLAG_STOP | NRFX_PWM_FLAG_NO_EVT_FINISHED);
I would expect the PWM to generate 100 pulses with 50% duty cycle.
This does not happen.
Only if I use a loop counter > 1 it seems that the repeats are being used.
So I would expect with a loop of 2 and a repeat of 100, I would get 200 pulses, but again no....
Documentation lacking information about the use of these values!
Anyway without fully understanding the values, I can get what I want by experimenting.
Now the second problem.....
With the simple code above, my applications reboots when trying to run the playback a second time. I will run the first time, but at second attemt the processor reboots (not hitting error handler).
I have been searching documentation, but no clues. Looking for documentation if I should stop it in any way, also a check using nrfx_pwm_is_stopped does not help...
