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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262-004US
695
Expansion Bus Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network
Processors
12.4.5.7
Back-to-Back 1-Word Inbound Reads with EX_SLAVE_CS_N
The above timing diagram shows two back-to-back 1-word read data transfers. For
reads, the Expansion bus controller will always assert EX_WAIT_N one cycle after the
assertion of EX_SLAVE_CS_N. As soon as the Expansion bus controller has the data it
will deassert EX_WAIT_N. The deassertion of EX_WAIT_N is dependent on system
activity and could be hundreds of cycles. After the master detects EX_WAIT_N
deasserted, it can deassert EX_SLAVE_CS_N. However, the master can choose to
extend cycle-4 and cycle-12 for as many cycles as it needs. The Expansion bus
controller will continue to drive the read data until the end of the data transfer. In the
second data transfer, the master chose to introduce 2 NOP cycles. The Expansion bus
controller must ignore EX_ADDR during NOP cycles.
Figure 156. Back-to-Back 1-Word Inbound Reads with EX_SLAVE_CS_N
B4444-01
EX_CLK
- 0 -
- 1 -
- 2 -
- 3 -
- 4 -
- 5 -
- 6 -
- 7 -
- 8 -
- 9 -
EX_ IXPCS_N
EX_ ADDR
EX_RD_N
EX_WR_N
EX_BE_N
EX_ BURST
EX_ WAIT_N
EX_ DATA
EX_ PARITY
STATE
- 10 -
- 11 -
- 12 -
- 13 -
- 14 -
ADDR0
PAR0
DATA0
ADDR1
IDLE
WAIT
DATA0
NOP
WAIT
PAR1
DATA1
DATA1
IDLE
IDLE