AT91FR40161 ATMEL Corporation, AT91FR40161 Datasheet - Page 32

• Manufacturer Part Number: AT91FR40161
• Description: The AT91FR40161 Features 136 K Bytes of On-chip SRAM, 2M Bytes of Flash, an External Bus Interface, a 3-channel Timer/Counter, 2 ...
• Manufacturer: ATMEL Corporation

Chip Select Change Wait
States
32
AT91X40 Series
Additional constraints are applicable to the AT91R40807, the AT91M40807 and the
AT91 40800. The behavior of the EBI is correct when NWAIT is asserted during an
external memory access:
•
•
These constraints are not applicable to the AT91R40008.
A chip select wait state is automatically inserted when consecutive accesses are made
to two different external memories (if no wait states have already been inserted). If any
wait states have already been inserted, (e.g., data float wait) then none are added.
Figure 21. Chip Select Wait
Notes:
When NWAIT is asserted before the first rising edge of MCKI
When NWAIT is de-asserted and at least one standard wait state remains to be
executed
1. Early Read Protocol
2. Standard Read Protocol
NCS1
NCS2
NWE
NRD
MCK
(1)
Mem 1
(2)
Chip Select Wait
Mem 2
1354D–ATARM–08/02