pwm

[D]

Hi every body,

There is a problem with pwm driver example in demo3 part! after downloading, the board led is just on as it must, but after changing top_value there is no changing in led brightness!

If somebody know, please let me know how to change the brightness?

Kind regards

[awneil]

D said:

after changing top_value

to what? and how did you change it?

[D]

Thank you for replying. i saw your post before which it was about set a fixed duty cycle. i want to turn the led on with different brightness . My main goal is using these different brightness for making different color in one RGB led.

i dont need the led go from 0 to 100 or vice versa. just a constant led brightness.

[D]

I mean to say that for example turning an led on with 80 percent brightness or 10 percent or...

[D]

moreover i put it bellow code instead of demo 3:

static void demo3(void)
{
    NRF_LOG_INFO("Demo 3");

    /*
     * This demo uses only one channel, which is reflected on LED 1.
     * The LED blinks three times (200 ms on, 200 ms off), then it stays off
     * for one second.
     * This scheme is performed three times before the peripheral is stopped.
     */

    nrf_drv_pwm_config_t const config0 =
    {
        .output_pins =
        {
            BSP_LED_0 | NRF_DRV_PWM_PIN_INVERTED, // 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_LOWEST,
        .base_clock   = NRF_PWM_CLK_2MHz,//NRF_PWM_CLK_125kHz,
        .count_mode   = NRF_PWM_MODE_UP,
        .top_value    = 32768, // = 0x8000
        .load_mode    = NRF_PWM_LOAD_COMMON,
        .step_mode    = NRF_PWM_STEP_AUTO
    };
    APP_ERROR_CHECK(nrf_drv_pwm_init(&m_pwm0, &config0, NULL));
    m_used |= USED_PWM(0);

    // This array cannot be allocated on stack (hence "static") and it must
    // be in RAM (hence no "const", though its content is not changed).
    static uint16_t /*const*/ seq_values[] =
    {
        0x3000,
//        0x2000,
//        0x4000,
//        0x6000,
//        0x7FFF,
//        0x8000
    };
    nrf_pwm_sequence_t const seq =
    {
        .values.p_common = seq_values,
        .length          = NRF_PWM_VALUES_LENGTH(seq_values),
        .repeats         = 0,
        .end_delay       = 0
    };

    (void)nrf_drv_pwm_simple_playback(&m_pwm0, &seq, 3, NRF_DRV_PWM_FLAG_LOOP);
}

[awneil]

So what, exactly, happens when you run that code?

And what were you expecting to happen?

And what testing / debugging / investigation have you done to find the problem?