Each endpoint buffer can be accessed by configuring a FIFO size and starting address. The endpoint index 16-bit register (USBEPIDX) is used with the USBTXFIFOSZ, USBRXFIFOSZ, USBTXFIFOADD, and USBRXFIFOADD registers.
USBEPIDX is shown in Figure 23-15 and described in Table 23-17.
Figure 23-15 USB Endpoint Index Register (USBEPIDX)
| LEGEND: R/W = Read/Write; R = Read only; -n =
value after reset |
Table 23-17 USB Endpoint Index Register (USBEPIDX) Field Descriptions| Bit | Field | Value | Description |
|---|
| 7-4 | Reserved | 0 | Reserved |
| 3-0 | EPIDX | 0-4h | Endpoint Index. This bit field configures which endpoint is accessed when reading or writing to one of the USB controller's indexed registers. A value of 0x0 corresponds to Endpoint 0 and a value of 0xF corresponds to Endpoint 15. |