Register Map
13-48
13.2.21.2
Receive Endpoint n Double-Buffer (EPn_RX_Db)
This bit is only for non-isochronous endpoints. For isochronous endpoints,
which are always double-buffered, this bit is endpoint size MSB.
This bit must be set by the local host to allow double buffering for receive
non-isochronous endpoint n. This is used to reduce number of transactions
resulting in NAK handshake.
1: Double buffer used for non-isochronous receive endpoint n.
0: No double buffer for non-isochronous receive endpoint n.
Value after local host reset or USB reset is unchanged.
13.2.21.3
Receive Endpoint n Size (EPn_RX_Size)
This paragraph includes description of EPn_RX.[14] bit for isochronous
endpoints.
This field contains the endpoint n FIFO size value. Status flags (the
Non_ISO_FIFO_Empty, the Non_ISO_FIFO_Full, the ISO_FIFO_Empty, the
ISO_FIFO_Full) and overrun and underrun conditions are based on this value
for all OUT transactions to endpoint n (see Table 13–23).
Table 13–23. Endpoint n Size Values
Non-Isochronous
[13:12]
Isochronous
[14:12]
00: 8 bytes
000: 8 bytes
01: 16 bytes
001: 16 bytes
10: 32 bytes
010: 32 bytes
11: 64 bytes
011: 64 bytes
100: 128 bytes
101: 256 bytes
110: 512 bytes
Reserved
Value after local host reset or USB reset is unchanged.