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919293949596979899100
...the world's most energy friendly microcontrollers
2012-04-24 - Giant Gecko Family - d0053_Rev0.96 100
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Table 9.1. RMU Reset Cause Register Interpretation
Register Value Cause
0bXXXX XXXX XXXX XXX1 A Power-on Reset has been performed. X bits are don't care.
0bXXXX XXXX 0XXX XX10 A Brown-out has been detected on the unregulated power.
0bXXXX XXXX XXX0 0100 A Brown-out has been detected on the regulated power.
0bXXXX XXXX XXXX 1X00 An external reset has been applied.
0bXXXX XXXX XXX1 XX00 A watchdog reset has occurred.
0bXXXX X000 0010 0000 A lockup reset has occurred.
0bXXXX X000 01X0 0000 A system request reset has occurred.
0bXXXX X000 1XX0 0XX0 The system as woken up from EM4.
0bXXXX X001 1XX0 0XX0 The system as woken up from EM4 on an EM4 wakeup reset request from pin.
0bXXXX X010 0XX0 0000 A Brown-out has been detected on Analog Power Domain 0 (AVDD0).
0bXXXX X100 0XX0 0000 A Brown-out has been detected on Analog Power Domain 1 (AVDD1).
0bXXXX 1XXX XXXX XXXX A Brown-out has been detected by the Backup BOD on VDD_DREG.
0bXXX1 XXXX XXXX XXXX A Brown-out has been detected by the Backup BOD on BU_VIN.
0bXX1X XXXX XXXX XXXX A Brown-out has been detected by the Backup BOD on unregulated power
0bX1XX XXXX XXXX XXXX A Brown-out has been detected by the Backup BOD on regulated power.
0b1XXX XXXX XXXX XXXX The system has been in Backup mode.
Note
When exiting EM4 with external reset, both the BODREGRST and BODUNREGRST in
RSTCAUSE might be set (i.e. are invalid)
9.3.2 Power-On Reset (POR)
The POR ensures that the EFM32GG does not start up before the supply voltage V
DD
has reached
the threshold voltage VPORthr (see Device Datasheet Electrical Characteristics for details). Before the
threshold voltage is reached, the EFM32GG is kept in reset state. The operation of the POR is illustrated
in Figure 9.2 (p. 100) , with the active low POWERONn reset signal. The reason for the “unknown”
region is that the corresponding supply voltage is too low for any reliable operation.
Figure 9.2. RMU Power-on Reset Operation
POWERONn
V
DD
tim e
V
Unknown
VPORthr
9.3.3 Brown-Out Detector Reset (BOD)
The EFM32GG has 4 brownout detectors, one for the unregulated 3.0 V power, one for the regulated
internal power, one for Analog Power Domain 0 (AVDD0), and one for Analog Power Domain 1 (AVDD1).