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Functional Overview
ARM DDI 0389B
Copyright © 2006 ARM Limited. All rights reserved.
2-33
Figure 2-19 shows a burst read with the
smc_wait_0
output of the memory used to
delay the transfer.
Note
•
Synchronous memories have a configuration register enabling
smc_wait_0
to be
asserted either on the same clock cycle as the delayed data or a cycle earlier. The
SMC only supports
smc_wait_0
being asserted one cycle early, enabling
smc_wait_0
to be initially sampled with the fed back clock and then with
smc_mclk0
before being used by the FSM. This enables the easiest timing
closure. Additionally, you must configure the memory for
smc_wait_0
to be
active LOW.
•
In synchronous operation, the SMC relies on the
smc_wait_0
signal being
deasserted HIGH to indicate that the memory can finish the transfer. When in
synchronous mode some memories do not deassert the
smc_wait_0
signal during
non-array read transfers. Non-array read transfers are typically status register
reads. To avoid stalling the system with these memories, in synchronous mode
you must not perform non-array read transfers with the memory and SMC.
Figure 2-19 Synchronous burst read
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Содержание PrimeCell PL241
Страница 20: ...Introduction 1 6 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Страница 60: ...Functional Overview 2 40 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Страница 94: ...Device Driver Requirements 5 6 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Страница 104: ...Signal Descriptions A 10 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...
Страница 110: ...Glossary Glossary 6 Copyright 2006 ARM Limited All rights reserved ARM DDI 0389B ...