9.4 Reset Sources and Supply Monitor Control Registers
9.4.1 RSTSRC: Reset Source
Bit
7
6
5
4
3
2
1
0
Name
USBRSF
FERROR
C0RSEF
SWRSF
WDTRSF
MCDRSF
PORSF
PINRSF
Access
RW
R
RW
RW
R
RW
RW
R
Reset
Varies
Varies
Varies
Varies
Varies
Varies
Varies
Varies
SFR Page = 0x0; SFR Address: 0xEF
Bit
Name
Reset
Access Description
7
USBRSF
Varies
RW
USB Reset Enable and Flag.
Read: This bit reads 1 if USB caused the last reset.
Write: Writing a 1 to this bit enables the USB0 module as a reset source.
6
FERROR
Varies
R
Flash Error Reset Flag.
This read-only bit is set to '1' if a flash read/write/erase error caused the last reset.
5
C0RSEF
Varies
RW
Comparator0 Reset Enable and Flag.
Read: This bit reads 1 if Comparator 0 caused the last reset.
Write: Writing a 1 to this bit enables Comparator 0 (active-low) as a reset source.
4
SWRSF
Varies
RW
Software Reset Force and Flag.
Read: This bit reads 1 if last reset was caused by a write to SWRSF.
Write: Writing a 1 to this bit forces a system reset.
3
WDTRSF
Varies
R
Watchdog Timer Reset Flag.
This read-only bit is set to '1' if a watchdog timer overflow caused the last reset.
2
MCDRSF
Varies
RW
Missing Clock Detector Enable and Flag.
Read: This bit reads 1 if a missing clock detector timeout caused the last reset.
Write: Writing a 1 to this bit enables the missing clock detector. The MCD triggers a reset if a missing clock condition is
detected.
1
PORSF
Varies
RW
Power-On / Supply Monitor Reset Flag, and Supply Monitor Reset
Enable.
Read: This bit reads 1 anytime a power-on or supply monitor reset has occurred.
Write: Writing a 1 to this bit enables the supply monitor as a reset source.
0
PINRSF
Varies
R
HW Pin Reset Flag.
This read-only bit is set to '1' if the RSTb pin caused the last reset.
Reads and writes of the RSTSRC register access different logic in the device. Reading the register always returns status information
to indicate the source of the most recent reset. Writing to the register activates certain options as reset sources. It is recommended to
not use any kind of read-modify-write operation on this register.
When the PORSF bit reads back '1' all other RSTSRC flags are indeterminate.
Writing '1' to the PORSF bit when the supply monitor is not enabled and stabilized may cause a system reset.
EFM8UB3 Reference Manual
Reset Sources and Power Supply Monitor
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