RM0321 Datasheet, PDF (168/584 Pages) STMicroelectronics – SPEAr320S address map and registers

USB 2.0 Device port (UDC)
RM0321
9.2.10
Endpoint buffer size and received packet frame number register
This is a dual-function endpoint-specific RW register which gives either the buffer size or the
TxFIFO associated to an in endpoint, or the frame number in which a packet is received an
out endpoint (useful to handle ISO traffic).
Table 163. Endpoint buffer size/received packet frame number register bit
assignments
Bit
Name
Reset value Description
[31:18] Reserved -
Read: undefined. Write: should be zero.
[17:16]
ISO PID
(IN/OUT)
2’h0
Initial data PID to be sent for a high-bandwidth ISO
transaction.
For IN
These 2 bits indicate the initial data PID to be transmitted for
an high-bandwidth ISO transaction, according to encoding:
– 2‘b00 = DATA0.
– 2‘b01 = DATA0.
– 2‘b10 = DATA1.
– 2‘b11 = DATA2.
For OUT,
These 2 bits indicate the initial data PID of the packet
received (that is, available in the RxFIFO) for an high-
bandwidth ISO transaction, according to encoding:
– 2'b00 = DATA0.
– 2'b01 = DATA1.
– 2'b10 = DATA2.
– 2'b11 = MDATA.
Note: The ISO PID field is used in slave-only mode, and it is
reserved for the UDC11.
[15:00]
BUFF SIZE
(IN)
16’h0000
For IN
Buffer size required for this endpoint.
This 16 bit field represents the size of the buffer associated
to that in endpoint as an integer number of 32 bit words.
Resulting flexibility in buffer size allows the application to
cope with interface or configuration changes.
For OUT
Frame number in which the packet is received.
This 16 bit field states the frame number in which an
incoming packet has been received by the RxFIFO for that
out endpoint, as follows:
-High-Speed (HS) operation
[15:14] Reserved.
[13:3] Millisecond frame number.
[2:0] Micro-frame number.
Full-Speed (FS) operation
[15:11] Reserved.
[10:0] Millisecond frame number
168/584
Doc ID 022642 Rev 3