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22.6.5
Setup and Hold Cycles
The SMC allows some memory devices to be interfaced with different setup, hold and pulse
delays. These parameters are programmable and define the timing of each portion of the read
and write cycles. However, it is not possible to use this feature in early read protocol.
If an attempt is made to program the setup parameter as not equal to zero and the hold parame-
ter as equal to zero with WSEN = 0 (0 standard wait state), the SMC does not operate correctly.
If consecutive accesses are made to two different external memories and the second memory is
programmed with setup cycles, then no chip select change wait state is inserted (see
Figure 22-When a data float wait state (t
DF) is programmed on the first memory bank and when the second
memory bank is programmed with setup cycles, the SMC behaves as follows:
If the number of t
DF is higher or equal to the number of setup cycles, the number of setup
If the number of the setup cycle is higher than the number of t
DF, the number of tDF inserted is
22.6.5.1
Read Access
The read cycle can be divided into a setup, a pulse length and a hold. The setup parameter can
have a value between 1.5 and 7.5 clock cycles, the hold parameter between 0 and 7 clock
cycles and the pulse length between 1.5 and 128.5 clock cycles, by increments of one.
Figure 22-19. Read Access with Setup and Hold
Figure 22-20. Read Access with Setup
NRD Setup
Pulse Length
NRD
A[22:0]
NRD Hold
MCK
NRD Setup
Pulse Length
NRD
A[22:0]
MCK