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Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
September 2006 DM
Order Number: 252480-006US 489
Universal Serial Bus (USB) v1.1 Device Controller—Intel
®
IXP42X product line and IXC1100
control plane processors
This bit must be polled when the UDCCS2[RPC] bit is set to determine if there is any
data in the FIFO that the Intel XScale
®
processor did not read. The receive FIFO must
continue to be read until this bit clears or data will be lost.
18.5.4.8 Receive Short Packet (RSP)
The UDC uses the receive short packet bit to indicate that the received OUT packet in
the active buffer currently being read is a short packet or zero-sized packet. This bit is
updated by the UDC after the last byte is read from the active buffer and reflects the
status of the new active buffer.
If UDCCS2[RSP] is a 1 and UDCCS2[RNE] is a 0, it indicates a zero-length packet. If a
zero-length packet is present, the Intel XScale
®
processor must not read the data
register. UDCCS2[RSP] is cleared when the next OUT packet is received.
Register Name: UDCCS2
Hex Offset Address: 0 x C800 B018 Reset Hex Value: 0 x 00000000
Register
Description:
Universal Serial Bus Device Controller Endpoint 2 Control and Status Register
Access: Read/Write
Bits
31 876543210
(Reserved)
RSP
RNE
FST
SST
DME
(Rsvd)
RPC
RFS
X 00000000
Resets (Above)
Register
UDCCS2
Bits Name Description
31:8 Reserved for future use.
7RSP
Receive short packet (read only).
1 = Short packet received and ready for reading.
6RNE
Receive FIFO not empty (read-only).
0 = Receive FIFO empty.
1 = Receive FIFO not empty.
5FST
Force stall (read/write).
1 = Issue STALL handshakes to OUT tokens.
4 SST
Sent stall (read/write 1 to clear).
1 = STALL handshake was sent.
3(Reserved)
2 (Reserved). Always reads zero.
1RPC
Receive packet complete (read/write 1 to clear).
0 = Error/status bits invalid.
1 = Receive packet has been received and error/status bits are valid.
0RFS
Receive FIFO service (read-only).
0 = Receive FIFO has less than one data packet.
1 = Receive FIFO has 1 or more data packets.