Rainbow Electronics AT91CAP9S250A - Manual (Page 200)

200
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
22.12.2 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 22-32 on
page 200 . The external device may not be fast enough to support such timings.
Figure 22-33 illustrates the recommended procedure to properly switch from one mode to the
other.
Figure 22-32. Clock Rate Transition Occurs while the SMC is Performing a Write Operation
A [25:2]
NCS
1
MCK
NWE
1 1
NWE_CYCLE = 3
SLOW CLOCK MODE WRITE
Slow Clock Mode
internal signal from PMC
1 1 1 2 3 2
NWE_CYCLE = 7
NORMAL MODE WRITE
Slow clock mode transition is detected:
Reload Configuration Wait State
This write cycle finishes with the slow clock mode set
of parameters after the clock rate transition
SLOW CLOCK MODE WRITE
NBS0, NBS1,
NBS2, NBS3,
A0,A1