Proper sequence to initialize PWM?

[nszmnsky]

I'm having difficulty with using PWM library with softdevice. The app_pwm_init function returns

NRF_SUCCESS but call to app_pwm_enable does not generate an output.

//PWM sound generation
APP_PWM_INSTANCE(PWMpiezo,1);

void pwm_ready_callback(uint32_t pwm_id)    // PWM callback function
{

}

void UI_pwm_init()
{
    ret_code_t err_code;

    app_pwm_config_t piezo_config = APP_PWM_DEFAULT_CONFIG_1CH(250UL,PIEZO); //4KHz 
    // Initialize the PWM library
    err_code = app_pwm_init(&PWMpiezo,&piezo_config,pwm_ready_callback);
    if(err_code == NRF_SUCCESS)
    {
	app_pwm_enable(&PWMpiezo);
     }
}

Documentation doesn't detail where init should take place but an answer to a question here says it should be before the ble_stack_init. Are there other restrictions on where it should be done?

Or do I have an error in the code that I can't see? Thanks! Neil

[Krzysztof Chruscinski]

It's not mentioned in the documentation but PWM should be initialized after SoftDevice. The thing is that PWM is using PPI driver which if softdevice is present access PPI through softdevice. It's recommended to initialize softdevice as one of the first things in the main().

[Susheel Nuguru]

sometimes it helps to do a side by side comparision and sometimes it doesn't. it is mostly timing with PWM so you need to compare the registers in the GPIOTE interrupt handler. may be you can post your full main.c file here and we can have a look. Which version of SD and SDK are you using?