pulse generation

RE: pulse generation

Stas — Fri, 02 Dec 2016 05:24:23 GMT

Thanks. I have some problem with triggering pwm sequence task by ppi here is my question devzone.nordicsemi.com/.../

RE: pulse generation

Sigurd — Thu, 01 Dec 2016 11:55:42 GMT

Yes, you dont need to call the whole function. How often do you need the function? You could split a large part of the code into a init-part, and then call the nrf_drv_pwm_simple_playback in the event handler. If you use the function very often it could be worth looking into using PPI. Here is a post on that.

RE: pulse generation

Stas — Thu, 01 Dec 2016 07:09:46 GMT

Thank you. This function is works for me. The following task would be to start this pulse sequince after trigger low level on other pin. But I think it's not correct to call this whole function from gpiote event handle?! I know the best way would be to use PPI, but I never used it before

RE: pulse generation

Sigurd — Wed, 30 Nov 2016 12:57:18 GMT

Hi,

For generating a fixed number of pulses, I suggested using the PWM driver(nRF52 only).

Here is a function called generate_pulse_1mhz(uint16_t pulses,uint8_t pin_number), it takes the number of 1 Mhz pulses you want to generate and the output pin number. When called it will output the desired number of pulses on the pin specified.

static nrf_drv_pwm_t m_pwm0 = NRF_DRV_PWM_INSTANCE(0);

static void generate_pulse_1mhz(uint16_t pulses,uint8_t pin_number)
{
    uint32_t err_code;
    nrf_drv_pwm_config_t const config0 =
    {
        .output_pins =
        {
            pin_number,                           // channel 0
            NRF_DRV_PWM_PIN_NOT_USED,             // channel 1
            NRF_DRV_PWM_PIN_NOT_USED,             // channel 2
            NRF_DRV_PWM_PIN_NOT_USED,             // channel 3
        },
        .irq_priority = APP_IRQ_PRIORITY_HIGH,
        .base_clock   = NRF_PWM_CLK_2MHz,
        .count_mode   = NRF_PWM_MODE_UP,
        .top_value    = 2,
        .load_mode    = NRF_PWM_LOAD_COMMON,
        .step_mode    = NRF_PWM_STEP_AUTO
    };
    err_code = nrf_drv_pwm_init(&m_pwm0, &config0, NULL);
    APP_ERROR_CHECK(err_code);
    
    static uint16_t /*const*/ seq_values[] ={1};
    
    nrf_pwm_sequence_t const seq =
    {
        .values.p_common = seq_values,
        .length          = NRF_PWM_VALUES_LENGTH(seq_values),
        .repeats         = 0,
        .end_delay       = 0
    };
    
    nrf_drv_pwm_simple_playback(&m_pwm0, &seq, pulses,  NRF_DRV_PWM_FLAG_STOP);
}