Hardware Abstraction Layer (HAL)#

The Hardware Abstraction Layer (HAL) is program code between a system's hardware and its software that provides a consistent interface for applications that can run on several different hardware platforms. To take advantage of this capability, applications should access hardware through the API provided by the HAL, rather than directly. Then, when you move to new hardware, you only need to update the HAL. In some cases, due to extreme differences in hardware, the HAL API may also change slightly to accommodate the new hardware. In these cases, the limited scope of the update makes moving the application easier with the HAL than without.

HAL function names have the following prefix conventions:

halCommon: API that is used by the EmberZNet stack and can also be called from an application. This API must be implemented. Custom applications can change the implementation of the API but its functionality must remain the same.
hal: API that is used by sample applications. Custom applications can remove this API or change its implementation as they see fit.
halStack: API used only by the EmberZNet stack. This API must be implemented and should not be directly called from any application. Custom applications can change the implementation of the API, but its functionality must remain the same.
halInternal: API that is internal to the HAL. The EmberZNet stack and applications must never call this API directly. Custom applications can change this API as they see fit. However, be careful not to impact the functionalty of any halStack or halCommon APIs.