为了更好的理解安卓的层次关系，本文在RK3399的安卓系统上增加LED灯的外设，并使用APP打开关闭LED灯。以这样一个最简单的实例，来演示从上层到底层的调用过程。首先从最底层的kernel层开始。 一、驱动开发 Kernel层就是要将LED硬件接入到系统，完成驱动的开发。

Rapid market growth for HB (high-brightness) LEDs is driving what was once a niche industry into full-fledged high-volume production. With the emergence of applications such as display backlighting, ...

Light Emitting Diode (LED) lighting has been gaining popularity in the wheeling world. Although still fairly expensive when compared to other technologies, LEDs offer a host of benefits that make them ...