EFM32WG Datasheet, PDF (115/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

• EMU_ROUTE
...the world's most energy friendly microcontrollers
Note
For registers residing in the CMU and EMU_AUXCTRL, the reset value will be read after
exit from EM4 or Backup mode, but if LOCKCONF in EMU_EM4CONF has been set, the
locked configuration will be used until LOCKCONF is cleared. This also applies for the
LOCKCONF bit itself.
10.3.4.10 EM4 with RTC and data retention
The backup power domain can also be powered by the main power. This provides possibility for
Backup RTC operation and data retention in EM4. Available functionality in EM4 is configured in
EMU_EM4CONF. Setting the VREGEN bit will keep the voltage regulator for the Backup domain enabled
when in EM4. This allows the Backup RTC to keep running. To enable the Backup RTC to wake up
the system from EM4, BURTCWU in EMU_EM4CONF needs to be set. When BURTCWU is set, any
enabled Backup RTC interrupt will wake up the system. For further details regarding the Backup RTC
and EM4 data retention, refer to Chapter 22 (p. 565) .
10.3.4.10.1 Oscillators in EM4
When the system is in EM4 or backup mode with the voltage regulator enabled, the ULFRCO is by
default enabled. If the LFXO or LFRCO is used by the Backup RTC, the ULFRCO can be shut down to
reduce power consumption. To do this, configure the OSC bitfield in EMU_EM4CONF.
Note
If OSC in EMU_EM4CONF is not set to ULFRCO, PRESC and LPCOMP in BURTC_CTRL
has to be configured in the following manner:
• 4 < (PRESC + LPCOMP) < 8, PRESC = 0,5,6,7
Refer to Chapter 22 (p. 565) for details on how to configure the Backup RTC.
10.3.4.10.2 Brown-out detector in EM4
To enable Brown-out detection in EM4, the Backup BODs have to be enabled, by setting EN in
EMU_BUCTRL. When BURDY in EMU_STATUS is set, the Brown-out detectors are ready and able to
issue a reset from EM4 if a Brown-out is detected on either regulated or unregulated power. The Backup
BOD' ability to issue reset from EM4 can be disabled by setting BUBODRSTDIS in EMU_EM4CONF.
Note
The Backup BODs can be enabled without allowing entrance to backup mode. This is done
by setting EN in EMU_BUCTRL, and clearing BUVINPEN in EMU_ROUTE.
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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