User Manual
BCM1250/BCM1125/BCM1125H
10/21/02
B r o a d c o m C o r p o r a t i o n
Document
1250_1125-UM100CB-R
Section 9: Ethernet MACs Page
309
Table 181: MAC VLAN Tag Registers
mac_vlantag_0 -
00_1006_4110
mac_vlantag_1 -
00_1006_5110
mac_vlantag_2 -
00_1006_6110
This register is used in both Ethernet and Packet FIFO modes
Bits
Name
Default
Description
31:0
tag
32'b0
VLAN tag. This 32 bit tag is inserted into the packet after the destination and source
Ethernet addresses if the packet is marked for VLAN tag insertion. The tag thus
becomes bytes 12-15 of the packet. The low byte in this register is the first one put
on the wire. Note that for normal VLAN operation the low two bytes should be
16’h8100.
Used only in Ethernet mode.
39:32
tx_pkt_offset
8’b0
System Revision PERIPH_REV3 and later only.
Sets the offset the Ethernet frame in transmitted packets. Bits 34:32 MUST be
3'b000.
Used in both Ethernet and Packet FIFO modes.
47:40
tx_crc_offset
8’b0
System Revision PERIPH_REV3 and later only.
Sets the offset for CRC generation to begin in transmitted packets. Bits 42:40 MUST
be 3'b000.
Used in both Ethernet and Packet FIFO modes.
48
ch_base_fc_en
1’b0
System Revision PERIPH_REV3 and later only.
If this bit is clear Pause frame flow control is done in the MAC, if set the flow control
is done by the DMA engine.
Used in both Ethernet and Packet FIFO modes.
63:49 notimp
32’b0
Not
Implemented.
Table 182: MAC Status Registers
mac_status_0 -
00_1006_4408
mac_status_1 -
00_1006_5408
mac_status_2 -
00_1006_6408
READ ONLY - Reading this register will clear all latched bits
This register is used in both Ethernet and Packet FIFO modes
Bits
Name
Default
Description
0
rx_ch0_eop_count
1’b0
Set if the EOP interrupt was raised as a result of the packet count being reached.
1
rx_ch0_eop_timer
1’b0
Set if the EOP interrupt was raised as a result of the packet timer triggered.
2
rx_ch0_eop_seen
1’b0
Set at the end of any packet transfer. It can be used during polling to determine if
any packets have been transferred since the register was read (regardless of the
setting of the int_pktcnt field).
3
rx_ch0_hwm
1’b0
This bit will be set if the current descriptor count is less than the high watermark.
This bit is not latched nor cleared by a read of the status register. It always reflects
the state at the time the register is read. Therefore it is possible that the bit may
become set and cause an interrupt but be cleared by an in-flight write that adds
descriptors before the interrupt is taken.
4
rx_ch0_lwm
1’b0
This bit will be set if the current descriptor count is less than the low watermark.
This bit is not latched (see bit 3).
5
rx_ch0_dscr
1’b0
Set if the interrupt is triggered by a descriptor with the interrupt bit set.