BCM1250/BCM1125/BCM1125H
User Manual
10/21/02
B r o a d c o m C o r p o r a t i o n
Page
296
Section 9: Ethernet MACs
Document
1250_1125-UM100CB-R
8-B
IT
SOP F
LAGGED
P
ACKET
FIFO
SOP flagged Packet FIFO mode uses one control line as a data valid signal and the other to flag start of packet.
The end of packet is one cycle before the SOP or whenever the data goes invalid (this extra EOP is required
to push out the last data at the end of a valid sequence).
Figure 62: 8-Bit Packet FIFO SOP Style
TXEN/RXDV
TXER/RXER
TXD/RXD[7:0]
TCLKO/RCLK
55
SOP
EOP SOP
EOP
Table 172: Codes for 8-Bit SOP Packet FIFO
TXEN / RXDV
TXER / RXER
Valid Data, Start of Packet
1
1
Valid Data
1
0
Valid Data, End of Packet
1
next cycle 1
1->0 at end of cycle
anything
Data Not Valid
0
anything