XR22804 Datasheet, PDF (31/47 Pages) Exar Corporation – Hi-Speed USB to 10/100 Ethernet Bridge with 4 UARTs

XR22804
RX_CONTROL (0x066) - Read/Write
Bit
15:2
1
0
Default
Description
0
Reserved
These bits are reserved and should be written as ‘0’.
0
Max_Pkt_Size
0: Maximum bulk-in packet size is 512 / 64 bytes in hi-speed / full-speed mode respectively (normal operation)
1: Maximum bulk-in packet size is 508 / 60 bytes in hi-speed / full-speed mode respectively (workaround for
known Windows OS CDC-ACM driver issue)
0
Low_Latency
0: Disable low latency mode
1: Enable low latency mode
FLOW_THRESHOLD (0x067) - Read/Write
Bit
15:11
10:0
Default
Description
0x0
Reserved
These bits are reserved and should be written as ‘0’.
0x2E0
Thresh
If enabled, flow control (either hardware or software), will be asserted when the RX FIFO fill level exceeds the
threshold value.
CUSTOM_DRIVER (0x081) - Read/Write
Bit
15:1
0
Default
Description
0x0000 Reserved
These bits are reserved and should be written as ‘0’.
0
Active
A custom driver should immediately enable this bit prior to using any CDC-ACM commands from the USB host,
to ensure that the XR22804 does not enter CDC mode and default to the values listed in Table 3.
© 2015 Exar Corporation
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exar.com/XR22804
Rev 1B