at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 190

• Manufacturer Part Number: at91sam9260-cj
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

21.11.2
Figure 21-26. Write Access with NWAIT Assertion in Frozen Mode (EXNW_MODE = 10)
190
internally synchronized
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NWAIT signal
AT91SAM9260
Frozen Mode
D[31:0]
NWAIT
A
NWE
[25:2]
MCK
NCS
6
When the external device asserts the NWAIT signal (active low), and after internal synchroniza-
tion of this signal, the SMC state is frozen, i.e., SMC internal counters are frozen, and all control
signals remain unchanged. When the resynchronized NWAIT signal is deasserted, the SMC
completes the access, resuming the access from the point where it was stopped. See
26. This mode must be selected when the external device uses the NWAIT signal to delay the
access and to freeze the SMC.
The assertion of the NWAIT signal outside the expected period is ignored as illustrated in
21-27.
4
5
4
3
3
2
1
2
Write cycle
EXNW_MODE = 10 (Frozen)
WRITE_MODE = 1 (NWE_controlled)
NWE_PULSE = 5
NCS_WR_PULSE = 7
1
2
FROZEN STATE
1
2
1
2
1
0
0
6221G–ATARM–31-Jan-08
Figure 21-
Figure