Intel IXP42X Personal Computer User Manual


 
Intel
®
IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
September 2006 DM
Order Number: 252480-006US 513
Universal Serial Bus (USB) v1.1 Device Controller—Intel
®
IXP42X product line and IXC1100
control plane processors
18.5.16.7 Receive FIFO Not Empty (RNE)
The receive FIFO not empty bit indicates that the receive FIFO has unread data in it.
When the UDCCS14[RPC] bit is set, this bit must be read to determine if there is any
data in the FIFO that Intel XScale
®
processor did not read.
The receive FIFO must continue to be read until this bit clears or data will be lost.
18.5.16.8 Receive Short Packet (RSP)
The receive short packet bit is used by the UDC 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 UDCCS14[RSP] is a 1 and UDCCS14[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.
UDCCS14[RSP] clears when the next OUT packet is received.
Register Name: UDCCS14
Hex Offset Address: 0x C800B048 Reset Hex Value: 0x00000000
Register
Description:
Universal Serial Bus Device Controller Endpoint 14 Control and Status Register
Access: Read/Write
Bits
31 876543210
(Reserved)
RSP
RNE
(Rsvd)
(Rsvd)
(Rsvd)
ROF
RPC
RFS
X 00000000
Resets (Above)
Register
UDCCS14 (Sheet 1 of 2)
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.
5 (Reserved). Always reads 0.
4 (Reserved). Always reads 0.
3(Reserved)