USB Host Layer Controller Numbers 

This constant defines the number of USB Host Controllers that this Host Layer must manage. The value of this constant should be atleast 1. Typical embedded applicatons contains only 1 USB host controller and hence only 1 USB. A microcontroller that features multiple USB modules can support multiple USB Host controllers and multipel USBs. USB contollers can also be interfaced to the microcontroller through common communication peripherals such as SPI. 

This constant also defines the number of entries in the Host Controller Driver interface table, a pointer to which is passed in the hostContollerDrivers member of the USB_HOST_INIT data structure.

#define USB_HOST_CONTROLLERS_NUMBER 

None.