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
370
Section 11: Generic/Boot Bus
Document
1250_1125-UM100CB-R
B
URST
M
ODE
A chip select region on the generic bus can be set in a burst mode. This allows faster throughput by only doing
a single address cycle at the start of the burst. However, there are some restrictions when in burst mode.
The burst operation is based on the standard cycle outlined in the previous sections. The start of the
transaction is the same with the address asserted with IO_ALE. The chip select and strobe (IO_OE_L or
IO_WR_L) are asserted and data transferred as normal. When the strobe deasserts (again with the normal
timing) either there are no more transfers in the transaction and the access ends in the usual way, or the chip
select remains asserted through an idle period of 2 or more cycles before the strobe reasserts for the next data.
This is shown in
and
and summarized in
Figure 78: Generic Bus Burst Read
Figure 79: Generic Bus Burst Write
IO_CLK100
IO_ALE
IO_CS_L
IO_OE_L
IO_AD[31:0]
IO_RW
ADR
D0
D1
D2
D6
D7
t0
t1
t2
t3
t3
t4
t5
t6
IO_CLK100
IO_ALE
IO_CS_L
IO_WR_L
IO_AD[31:0]
IO_RW
ADR
D0
D1
D2
D6
D7
t0
t1
t2
t3
t3
t4
t5
t6
Содержание BCM1125
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