4.3.2 Reading
When reading from a Low Energy Peripheral, the data read is synchronized regardless if it originates in the Low Energy clock domain
or High Frequency clock domain. See
Figure 4.13 Read Operation From Low Energy Peripherals on page 54
reading operation.
Note:
Writing a register and then immediately reading the new value of the register may give the impression that the write operation is
complete. This may not be the case. Refer to the SYNCBUSY register for correct status of the write operation to the Low Energy Pe-
ripheral.
Register 0
Register 1
.
.
.
Register n
Synchronizer 0
Synchronizer 1
.
.
.
Synchronizer n
Register 0 Sync
Register 1 Sync
.
.
.
Register n Sync
Freeze
High Frequency Clock
Low Frequency Clock
Low Frequency Clock
High Frequency Clock Domain
Low Frequency Clock Domain
Low Energy
Peripheral
Main
Function
HW Status Register 0
HW Status Register 1
.
.
.
HW Status Register m
Read
Synchronizer
Read Data
Figure 4.13. Read Operation From Low Energy Peripherals
4.3.3 FREEZE Register
In all Low Energy Peripheral with delayed synchronization there is a <module_name>_FREEZE register (e.g. RTCC_FREEZE). The
register contains a bit named REGFREEZE. If precise control of the synchronization process is required, this bit may be utilized. When
REGFREEZE is set, the synchronization process is halted allowing the software to write multiple Low Energy registers before starting
the synchronization process, thus providing precise control of the module update process. The synchronization process is started by
clearing the REGFREEZE bit.
Note:
The FREEZE register is also present on peripherals with immediate synchronization, but there it has no effect
4.4 Flash
The Flash retains data in any state and typically stores the application code, special user data and security information. The Flash
memory is typically programmed through the debug interface, but can also be erased and written to from software.
• Up to 256 KB of memory
• Page size of 2 KB (minimum erase unit)
• Minimum 10K erase cycles endurance
• Greater than 10 years data retention at 85 °C
• Lock-bits for memory protection
• Data retention in any state
Reference Manual
Memory and Bus System
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