This is an example code of controlling a ws2812b led stripe, with 18 leds thus the used library is configured as 1 row with 18 cols. You can change row and col in the ws2812b header file. You can connect up to 16 led stripes. Data is written in parallel to the stripes from a GPIO Bank (GPIO A in this example) This is why up to 16 stripes can be controlled in parallel. A Timer is used in which 3 DMA transfers are triggered used to write data to the gpios on which the stripes are connected to. These 3 DMA transfers are triggered as following: First trigger is on each timer update event. It sets all gpios to high. Second trigger is on the first capture compare event on the 9th tick/pulse. The GPIOS are set accordingly if the bit for the ws2812b shall be a 1 or a 0 in the output buffer "WS2812_Buffer". The third trigger is the second capture compare event and sets all gpios always to 0 through a dma transfer. It doesn't matter if the pins are already set to 0 by the first capture compare event. Please read the ws2812b datasheet to understand the communication protocol with the ws2812b led chips. This example is programmed in the IAR Embedded Workbench IDE for a stm32f103 and tested on the famous Blue-Pill. But you can use this library for any other IDE or stm32 microcontroller. Just be sure to set the correct DMA streams/channels, otherwise it won't work.
