EFM32WG Datasheet, PDF (591/834 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
23.3.6 Register access
his module is a Low Energy Peripheral, and supports immediate synchronization. For description
regarding immediate synchronization, the reader is referred to Section 5.3.1.1 (p. 22) .
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
591
www.energymicro.com