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
311
26
tx_ch1_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).
27
tx_ch1_hwm
1’b0
This bit will be set if the current descriptor count is less than the high watermark.
This bit is not latched (see bit 3).
28
tx_ch1_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).
29
tx_ch1_dscr
1’b0
Set if the interrupt is triggered by a descriptor with the interrupt bit set.
30
tx_ch1_derr
1’b0
Set if data marked with an error is returned for any read (descriptor or data buffer).
The channel will be stopped. Software must disable and re-enable the channel to
clear this fault.
31
tx_ch1_dzero
1’b0
Set if a descriptor has a packet length of zero or the SOP flag bit is not set in the
first descriptor of a packet. This bit is also set if the controller runs out of descriptors
during a packet transmission. The channel will be stopped. Software must disable
and re-enable the channel to clear this fault.
39:32
Reserved 8’b0
Reserved
40
rx_undrfl
1'b0
This bit is set by the receive FIFO underflowing. If this happens when DMA is being
used then the rx_rd_thrsh is incorrectly set.
41
rx_ovrfl
1'b0
This bit is set by the receive FIFO overflowing. This happens if the DMA (or reader
in direct mode) has delayed reading data from the FIFO so there is no space for
the next received data.
42
tx_undrfl
1'b0
This bit is set if the transmit FIFO underflows. This happens if the DMA (or sender
in direct mode) has delayed inserting data into the FIFO and it was empty when
more data was needed to be transmitted.
43
tx_ovrfl
1'b0
This bit is set by the transmit FIFO overflowing. This happens if the DMA (or sender
in direct mode) writes to the FIFO when it is full. This will only happen for DMA if
the tx_wr_thrsh threshold is incorrectly set.
44
ltcol_err
1'b0
This bit will be set when a packet experiences a late collision. A late collision is
one that happens after the minimum packet size has been sent. Collisions can
never happen in Packet FIFO modes.
45
excol_err
1'b0
This bit is set if a packet experiences excessive collisions. It is signalled when
attempted transmission of the packet collides 16 times. It normally indicates a
hardware problem, but can also be caused by a very busy network or in the unlucky
case of the random backoff LFSR being synchronized with another host (normally
this will be fixed by the different length of time the two devices take to respond and
clear the excessive collision error, but it is also possible to set a different lfsr_seed
in the mac_cfg register). Collisions can never happen in Packet FIFO modes.
46
cntr_ovrfl_err
1'b0
This bit is set if any of the RMON counters overflow. Whenever a counter overflows
this bit is set and the counter number is written into the counter_addr field. The
RMON counters are not used in Packet FIFO modes.
51:47 counter_addr
5'b0
This is the number of the most recent RMON counter that overflowed. It is only
valid if the cntr_ovrfl_err bit is set. The RMON counters are not used in Packet
FIFO modes.
Table 182: MAC Status Registers
(Cont.)
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