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ATSAM4S-XPLD
406
SAM4S [DATASHEET]
11100E–ATARM–24-Jul-13
Figure 26-16.Early Read Wait State: NWE-controlled Write with No Hold Followed by a Read with one Set-up Cycle
26.10.3 Reload User Configuration Wait State
The user may change any of the configuration parameters by writing the SMC user interface.
When detecting that a new user configuration has been written in the user interface, the SMC inserts a wait state before
starting the next access. The so called “Reload User Configuration Wait State” is used by the SMC to load the new set of
parameters to apply to next accesses.
starting the next access. The so called “Reload User Configuration Wait State” is used by the SMC to load the new set of
parameters to apply to next accesses.
The Reload Configuration Wait State is not applied in addition to the Chip Select Wait State. If accesses before and after
re-programming the user interface are made to different devices (Chip Selects), then one single Chip Select Wait State is
applied.
re-programming the user interface are made to different devices (Chip Selects), then one single Chip Select Wait State is
applied.
On the other hand, if accesses before and after writing the user interface are made to the same device, a Reload
Configuration Wait State is inserted, even if the change does not concern the current Chip Select.
Configuration Wait State is inserted, even if the change does not concern the current Chip Select.
26.10.3.1User Procedure
To insert a Reload Configuration Wait State, the SMC detects a write access to any SMC_MODE register of the user
interface. If the user only modifies timing registers (SMC_SETUP, SMC_PULSE, SMC_CYCLE registers) in the user
interface, he must validate the modification by writing the SMC_MODE, even if no change was made on the mode
parameters.
interface. If the user only modifies timing registers (SMC_SETUP, SMC_PULSE, SMC_CYCLE registers) in the user
interface, he must validate the modification by writing the SMC_MODE, even if no change was made on the mode
parameters.
The user must not change the configuration parameters of an SMC Chip Select (Setup, Pulse, Cycle, Mode) if accesses
are performed on this CS during the modification. Any change of the Chip Select parameters, while fetching the code
from a memory connected on this CS, may lead to unpredictable behavior. The instructions used to modify the
parameters of an SMC Chip Select can be executed from the internal RAM or from a memory connected to another CS.
are performed on this CS during the modification. Any change of the Chip Select parameters, while fetching the code
from a memory connected on this CS, may lead to unpredictable behavior. The instructions used to modify the
parameters of an SMC Chip Select can be executed from the internal RAM or from a memory connected to another CS.
A[25:2]
write cycle
(WRITE_MODE = 1)
Early Read
wait state
MCK
NRD
internal write controlling signal
external write controlling signal
(NWE)
D[7:0]
read cycle
no hold
read setup = 1
(READ_MODE = 0 or READ_MODE = 1)