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ADM5120
Function Description
Bit
Description
31-27
Reserved
26-16
Maximum packet size
The maximum data that can transmit/receive in one USB transaction.
15
Format
This bit indicates that this packet is for isochronous.
1: The data in this descriptor is for isochronous transfer.
0: The data in this descriptor is for general data transfer.
14
Skip
When this bit is set, DMA will continue on the next descriptor in the link list, this is used for
isochronous and periodic data transmission/reception.
13
Speed
This bit indicates that the speed of the data transfer.
12
Reserved
11
INT
This bit indicate this ED is an interrupt endpoint
10-7
EN
Endpoint number of the current USB function.
6-0
FA
Function address of the current USB device.
DWORD 1 – Tail Transfer Descriptor
Bit
Description
31-4
Starting address of the tail transfer descriptor in host memory space
3-0
Reserved
DWORD 2 – Head Transfer Descriptor
Bit
Description
31-4
Starting address of the head transfer descriptor in host memory space
3-2
Reserved
1
Togglecarry
This bit indicate the current toggle value in this transaction.
0
Halt
This bit indicates that this endpoint is halted due to error.
DWORD 2 – Next Endpoint Transfer Descriptor
Bit
Description
31-4
Starting address of the next endpoint transfer descriptor in host memory space
3-0
Reserved
3.5.2 Transfer Descriptor Format
31 16 0
DWORD 0
CONTROL
DWORD 1
BUFFER ADDRESS
DWORD 2
BUF LENGTH
DWORD 3
NEXT DESCRIPTOR ADDRESS
ADMtek Inc.
3-12