Техническая Спецификация для Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK
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Модели
AT91SAM9N12-EK
Tightly-Coupled Memory Interface
ARM DDI0198D
Copyright © 2001-2003 ARM Limited. All rights reserved.
5-15
Figure 5-9 Cycle timing of loopback circuit
In cycle T1, a nonsequential request is made to address A and IRWAIT is asserted.
In cycle T2, IRSEQ is asserted because of the wait-state. IRWAIT is deasserted. IRCS
is unknown.
is unknown.
In cycle T3, the access to A completes and a sequential request is made to A+1. IRSEQ
is HIGH and IRWAIT is LOW
is HIGH and IRWAIT is LOW
In cycle T4, the access to A+1 completes. No new request is issued. The values of
IRSEQ and IRWAIT are unknown.
IRSEQ and IRWAIT are unknown.
In cycle T5, a nonsequential request is made to address B and IRWAIT is asserted
In cycle T6, IRSEQ is asserted because of the wait-state. IRWAIT is deasserted, IRCS
is unknown.
is unknown.
In cycle T7, the access to B completes.
For systems that also require DMA access to non zero wait state memories, the WAIT
signal is used to stall the ARM92EJ-S processor for both wait states and DMA
arbitration. Apart from the DRWD/IRWD write data signals, the information required
to perform an access is only valid during the request cycle for that access. If a TCM
access is postponed because of DMA, this information must be captured at the end of
the request cycle.
signal is used to stall the ARM92EJ-S processor for both wait states and DMA
arbitration. Apart from the DRWD/IRWD write data signals, the information required
to perform an access is only valid during the request cycle for that access. If a TCM
access is postponed because of DMA, this information must be captured at the end of
the request cycle.
Figure 5-10 on page 5-16 shows an example of a system where DMA access is required
to a memory that has a single wait state for nonsequential accesses.
to a memory that has a single wait state for nonsequential accesses.
CLK
IRCS
IRWAIT
IRRD
T1
T2
T3
T4
T5
T6
IRADDR
A
A+1
I(A)
I(B)
IRSEQ
T7
B
I(A+1)