NRF52840DK driving Neopixel is flickering

RE: NRF52840DK driving Neopixel is flickering

melt — Sat, 05 Feb 2022 06:17:27 GMT

Thank you

RE: NRF52840DK driving Neopixel is flickering

Sigurd — Fri, 04 Feb 2022 10:30:29 GMT

[quote user="melt777"]No more flickering or flashing. I can address each LED individually and I can adjust the brightness.[/quote]

Great!

[quote user="melt777"]How do I set the color?[/quote]

Here is the doc for drv_ws2812_set_pixel:

/**@brief Function for setting the specified pixel in the LED state buffer to the specified color.
 *
 * @param[in] pixel_no  Number of the pixel in the LED chain.
 *                      Specify a value in the range from 0 to @ref WS2812_LED_CHAIN_PIXELS_COUNT_MAX-1.
 *                      Values out of the range are ignored.
 * @param[in] color     Color to be set. Use the RGB format. Bits 23 to 16 are for the red component,
 *                      bits 15 to 8 are for the green component, and bits 7 to 0 are for the blue component.
 *
 * @note Call @ref drv_ws2812_display to update the LED chain from the frame buffer.
 */
void drv_ws2812_set_pixel(uint32_t pixel_no, uint32_t color);

So for red, try setting color to e.g. 16711680 (bit 23 to 16 set to 1).

RE: NRF52840DK driving Neopixel is flickering

melt — Fri, 04 Feb 2022 09:57:34 GMT

The Bulb example has proven most useful. I have removed all the Zigbee code and files and was left with a barebone framework to experiment with the neopixel driver. No more flickering or flashing. I can address each LED individually and I can adjust the brightness. But for some reason im only get shades of blue.

my code below

#include "sdk_config.h"
#include "bsp.h"
#include "boards.h"
#include "app_pwm.h"
#include "app_timer.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "drv_ws2812.h"
#define LED_CHAIN_DOUT_PIN                NRF_GPIO_PIN_MAP(1,7)                 /**< GPIO pin used as DOUT (to be connected to DIN pin of the first ws2812 led in chain) */
#define DRV_WS2812_LED_CHAIN_PIXELS_COUNT_MAX 20


#if (APP_BULB_USE_WS2812_LED_CHAIN)
/**@brief Timer responsible for triggering periodic led chain refresh */
APP_TIMER_DEF(m_ws2812_refresh_timer);

/** @brief Requests a led chain refresh */
static volatile bool m_ws2812_refresh_request;
#endif

/**@brief Function for initializing the application timer.
 */
static void timer_init(void)
{
    uint32_t error_code = app_timer_init();
    APP_ERROR_CHECK(error_code);
}

/**@brief Function for initializing the nrf log module.
 */
static void log_init(void)
{
    ret_code_t err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();
}


/**@brief Callback for button events.
 *
 * @param[in]   evt      Incoming event from the BSP subsystem.
 */
static void buttons_handler(bsp_event_t evt)
{

}


/**@brief Function for initializing LEDs and a single PWM channel.
 */
static void leds_buttons_init(void)
{


}

/**@brief Function for application main entry.
 */
int main(void)
{
       /* Initialize timer, logging system and GPIOs. */
    timer_init();
    log_init();
    leds_buttons_init();
    drv_ws2812_init(LED_CHAIN_DOUT_PIN);
    drv_ws2812_set_pixel_all(60);

     //   drv_ws2812_set_pixel_all(25);
   drv_ws2812_display(NULL, NULL);
}


/**
 * @}
 */

How do I set the color? according to the driver the 2nd variable should set the RGB color.

drv_ws2812_set_pixel(uint32_t pixel_no, uint32_t color);

but my 2nd variable set brightness (of blue only)

RE: NRF52840DK driving Neopixel is flickering

melt — Thu, 03 Feb 2022 12:45:12 GMT

Thanks Sigurd. I suspect that I2S is the problem here. I can successfully drive these LEDs with a Particle Photon board, so I know the hardware is working. With only 1 LED it works find but as soon as I add more Neopixels the flickering becomes more noticeable. With 20 LEDs they are definitely switching on and off as if the FOR(;;) loop is to slow. Hence me playing with the i2s_init() function to increase the frequency. I have also noted that setting channels Left or Right only lights up every 2nd LED.

Will play around with the light_bulb example today -

RE: NRF52840DK driving Neopixel is flickering

Sigurd — Thu, 03 Feb 2022 12:11:44 GMT

Hi,

This post might be helpful: https://devzone.nordicsemi.com/f/nordic-q-a/72958/ws2812-driver

PS: The mentioned ws2812 driver in the light_bulb example uses PWM and not i2s.