Product specifications

VT8237R Data Sheet
Revision 2.06 December 15, 2004 -155- Device 18 Function 0 LAN Registers
Offset 23-20 – Receive Status (0000 0400h).....................RW
31 Descriptor Owner
0 Descriptor Owned By Host (NIC cannot
access descriptor)
1 Descriptor Owned by NIC (NIC can access
descriptor)
This bit has no default so must be set by the driver at
initialization.
30-27 Reserved ........................................ always reads 0
26-16 Received Packet Length ........................ RO, def = 0
15 Received Packet Successfully................ RO, def = 0
14 Reserved ........................................ always reads 0
13 NIC Accepted Multicast Packet............ RO, def = 0
12 NIC Accepted Broadcast Packet........... RO, def = 0
11 NIC Accepted Physical Address PacketRO, def = 0
10 Chain Buffer....................................... always reads 1
Set if packet too large to occupy a single receive
descriptor.
9-8 Buffer Descriptor Start / End .............................RO
For packets too large to fit into a single receive
descriptor and thus occupy multiple RD’s, this field
reports whether this RD is the start, middle or end.
00 Chain Buffer Middle Descriptor ............default
01 Chain Buffer End Descriptor
10 Chain Buffer Start Descriptor
11 Single Buffer Descriptor (packet accupies only
one descriptor)
7 Reserved ...................................... Do not program
6 System Error .................................... RO, default = 0
5 Runt Packet (< 64 bytes).................. RO, default = 0
4 Long Packet (> 2500 bytes) ............. RO, default = 0
3 FIFO Overflow Error...................... RO, default = 0
2 Frame Alignment Error .................. RO, default = 0
1 CRC Error ...................................... RO, default = 0
0 Receiver Error ................................. RO, default = 0
Offset 27-24 – Rx Data Buffer Control (0000 0000h) .... RO
31-11 Reserved ........................................always reads 0
10-0 Rx Data Buffer Size.................................. default = 0
The receive data buffer size for this descriptor. The
total byte count of the entire frame will be stored in
the last descriptor.
Offset 2B-28 – Rx Data Buffer Start Address ................. RO
31-0 Rx Data Buffer Start Address
Offset 2F-2C – Rx Data Buffer Branch Address ............ RO
31-0 Rx Data Buffer Branch Address
Note: Rx20-2F reflect values from the RD being accessed.