AT91CAP7S450A_1 Datasheet, PDF (153/517 Pages) ATMEL Corporation – Customizable Microcontroller

AT91CAP7S450A [Preliminary]
21.12.2
Switching from (to) Slow Clock Mode to (from) Normal Mode
When switching from slow clock mode to the normal mode, the current slow clock mode transfer
is completed at high clock rate, with the set of slow clock mode parameters.See Figure 21-32 on
page 153. The external device may not be fast enough to support such timings.
Figure 21-33 illustrates the recommended procedure to properly switch from one mode to the
other.
Figure 21-32. Clock Rate Transition Occurs while the SMC is Performing a Write Operation
Slow Clock Mode
internal signal from PMC
MCK
A[25:2]
NBS0, NBS1,
NBS2, NBS3,
A0,A1
NWE
NCS
1
1
1
1
11
2
3
2
NWE_CYCLE = 3
NWE_CYCLE = 7
SLOW CLOCK MODE WRITE SLOW CLOCK MODE WRITE NORMAL MODE WRITE
This write cycle finishes with the slow clock mode set
of parameters after the clock rate transition
Slow clock mode transition is detected:
Reload Configuration Wait State
5119D–CAP–05/09
153