实现WS2812小灯控制，pwm口直接对接(Realize WS2812 small lamp control, direct docking of pwm port)

ws2812b全彩LED灯，采用pwm+dma方式控制，已经编写好红色呼吸灯、绿色呼吸灯、蓝色呼吸灯和随机呼吸灯程序，还有最基本的RGB三种颜色的0~255亮度调节函数。(ws2812b full-color LED lamp is controlled by pwm + dma mode. The program of red breathing lamp, Green Breathing lamp, blue breathing lamp and random breathing lamp