STM32 LED Strip (WS2812b) control 1: Theory and implementation

Source code and PDF document:
www.patreon.com/user?u=80399744
Website:
www.steppeschool.com
This video is about controlling NeoPixel (WS2812) LEDs using the STM32 MCUs. The idea is to generate a PWM signal with varying duty cycles:
HAL_TIM_PWM_Start_DMA
HARDWARE:
NeoPixel Board:
www.digikey.fr/fr/products/de...
STM32 Board: STM32F411E-DISCO
00:00 Introduction
00:29 WS2812 Theory
02:50 CubeMx PWM configuration for WS2812
04:50 Code explanation

[@steppeschool3629]

I am happy to announce that I have a Patreon page🙂 where you can access projects' source code, including this one: patreon.com/user?u=80399744&Link&

[@brianblasius]

I understand how these addressable LEDs work after watching this video. Keep doing great work. 💪

[@steppeschool3629]

Thanks, will do!

[@user-ox4qj7ue9x]

hey I have one doubt I want to connect more led stripes in parallel then i want use the different timer pwm but I have problem in the configuration DMA request another timer dma does not show that dma trigger option But I will change the code like that but my code run only single timer In my main c this for tim 2 reset_all_leds(leds, NUMBER_OF_LEDS);
HAL_TIM_PWM_Start_DMA(&htim2, TIM_CHANNEL_3, (uint32_t*)leds, NUMBER_OF_LEDS1 * 24 + 24);
HAL_Delay(300);
set_all_leds(leds, NUMBER_OF_LEDS1);
HAL_TIM_PWM_Start_DMA(&htim2, TIM_CHANNEL_3, (uint32_t*)leds, NUMBER_OF_LEDS1 * 24 + 24); and
this one is same code
tim 3
led_pos_counter++;
if(led_pos_counter == NUMBER_OF_LEDS)
{
led_pos_counter = 0;
}
temp_neo_pixel = circular_pattern_led[led_pos_counter + NUMBER_OF_LEDS];
circular_pattern_led[led_pos_counter + NUMBER_OF_LEDS];
circular_pattern_led[2* NUMBER_OF_LEDS];
HAL_TIM_PWM_Start_DMA(&htim3, TIM_CHANNEL_1, (uint32_t*)&circular_pattern_led[led_pos_counter], NUMBER_OF_LEDS * 24 + 24);
HAL_Delay(100);
circular_pattern_led[led_pos_counter + NUMBER_OF_LEDS] = temp_neo_pixel;

[@amiral3187]

It works well but I'm a bit confused about the data structure newpixel_led, why are you using uint16_t instead of uint8_t? and why a 3 elements of that size if every color is represented with only 8-bits?

[@steppeschool3629]

Hi,
If we look at the data structure:
typedef struct
{
uint16_t g[8];
uint16_t r[8];
uint16_t b[8];
} neopixel_led;
Each member is an array with 8 elements, corresponding to the number of bits per color. For each bit, we need to generate a PWM signal with a particular duty cycle. For that purpose, we need 16-bit values. Hope I could answer your question.