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Functional Overview
ARM DDI 0389B
Copyright © 2006 ARM Limited. All rights reserved.
2-19
smc_msync0
When HIGH, indicates
smc_mclk0
is synchronous to
smc_aclk
.
Otherwise they are asynchronous. Ensure that
smc_msync0
is tied to the
same value as
smc_async0
.
smc_rst_bypass
Use this signal for ATPG testing only. Tie it LOW for normal operation.
smc_use_ebi
When HIGH, indicates that the SMC must operate with a PrimeCell EBI.
See the
ARM PrimeCell External Bus Interface (PL220) Technical
Reference Manual
.
2.4.4
APB slave interface operation
To enable a clean registered interface to the external infrastructure, the APB interface
always adds a wait state for all reads and writes by driving
pready
LOW during the first
cycle of the access phase.
In two instances, a delay of more than one wait state can be generated:
•
when a direct command is received and there are outstanding commands that
prevent a new command being stored in the command FIFO
•
when an APB access is received and a previous direct command has not
completed.
2.4.5
Format block
This section describes:
•
Hazard handling
•
SRAM memory accesses
on page 2-20.
Hazard handling
There are four types of hazard:
•
Read After Read
(RAR)
•
Write After Write
(WAW)
•
Read After Write
(RAW)
•
Write After Read
(WAR).
The AHB interface deals with RAW hazards. WAR hazards do not occur in the AHB.
Summary of Contents for PrimeCell PL241
Page 20: ...Introduction 1 6 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Page 60: ...Functional Overview 2 40 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Page 94: ...Device Driver Requirements 5 6 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Page 104: ...Signal Descriptions A 10 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Page 110: ...Glossary Glossary 6 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...