The USB transmit dynamic FIFO sizing 8-bit register (USBTXFIFOSZ) allows the selected TX endpoint FIFOs to be dynamically sized. USBEPIDX is used to configure each transmit endpoint's FIFO size.
USBTXFIFOSZ is shown in Figure 22-20 and described in Table 22-22.
Figure 22-20 USB Transmit Dynamic FIFO Sizing Register (USBTXFIFOSZ)
LEGEND: R/W = Read/Write; R = Read only; -n =
value after reset |
Table 22-22 USB Transmit Dynamic FIFO Sizing Register (USBTXFIFOSZ) Field DescriptionsBit | Field | Value | Description |
---|
7-5 | Reserved | 0 | Reserved |
4 | DPB | | Double Packet Buffering Support |
0 | Single packet buffering is supported. |
1 | Double packet buffering is enabled. |
3-0 | SZ | | Maximum packet size to be allowed. If DPB = 0, the FIFO also is this size; if DPB = 1, the FIFO is twice this size. Packet size in bytes: |
0h | 8 |
1h | 16 |
2h | 32 |
3h | 64 |
4h | 128 |
5h | 256 |
6h | 512 |
7h | 1024 |
8h | 2048 |
9-Fh | Reserved |