EFM32WG Datasheet, PDF (38/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

...the world's most energy friendly microcontrollers
During a write or erase, flash read accesses will be stalled, effectively halting code
execution from flash. Code execution continues upon write/erase completion. Code residing
in RAM may be executed during a write/erase operation.
7.3.6.1 Mass erase
A mass erase can be initiated from software using ERASEMAIN0 in MSC_WRITECMD. This command
will start a mass erase of the entire flash. Prior to initiating a mass erase, MSC_MASSLOCK must be
unlocked by writing 0x631A to it. After a mass erase has been started, this register can be locked again
to prevent runaway code from accidentally triggering a mass erase.
The regular flash page lock bits will not prevent a mass erase. To prevent software from initiating mass
erases, use the mass erase lock bits in the mass erase lock word (MLW).
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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