After using MHC to configure the Static USART drivers, click the MHC "Generate" button to create the driver code.
Clicking the "Generate" button will create these two files and include them in your project for you:
MHC needs to generate static functions for you, because they are dependent on how you configure the static driver. These customized static driver functions are not downloaded with the rest of the Harmony framework. That is why you won't find the static driver source files included with the dynamic driver source files in the main Harmony framework folder.
drv_usart_static.c is created by MHC to create the USART Static Driver initialization function for each driver instance (driver instance 0 shown below). It will also create the other USART static driver functions.
system_init.c is modified by MHC to call the USART Static Driver initialization function.