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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—USB 1.1 Device
Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
344
Order Number: 306262-004US
8.5.34
UDC Data Register 4
(UDDR4)
Endpoint 4 is a double-buffered, isochronous OUT endpoint that is 256 bytes deep. The
UDC generates an interrupt when the EOP is received.
Because it is double-buffered, up to two packets of data may be ready. The data can be
removed from the UDC via a direct read from the Intel XScale processor. If one packet
is being removed and the packet behind it has already been received, the UDC issues a
NAK to the host the next time it sends an OUT packet to Endpoint 4.
This NAK condition remains in place until a full packet space is available in the UDC at
Endpoint 4.
Register Name:
UDDR3
Hex Offset Address:
0 x C800B200
Reset Hex Value:
0x00000000
Register
Description:
Universal Serial Bus Device Endpoint 3 Data Register
Access:
Write
Bits
31
16 15
8
7
0
(Reserved)
(8-Bit Data)
X
0
0
0
0
0
0
0
0
Resets (Above)
Register
UDDR3
Bits
Name
Description
31:8
Reserved for future use.
7:0
DATA
Top of endpoint data currently being loaded.
Register Name:
UDDR4
Hex Offset Address:
0 x C800B400
Reset Hex Value:
0x00000000
Register
Description:
Universal Serial Bus Device Endpoint 4 Data Register
Access: Read
Bits
31
8
7
0
(Reserved)
(8-Bit Data)
X
0
0
0
0
0
0
0
0
Resets (Above)
Register
UDDR4
Bits
Name
Description
31:8
Reserved for future use.
7:0
DATA
Top of endpoint data currently being read.