10.3.7 PCA Watchdog Timer Reset
The programmable watchdog timer (WDT) function of the programmable counter array (PCA) can be used to prevent software from
running out of control during a system malfunction. The PCA WDT function can be enabled or disabled by software as described in the
PCA documentation. The WDT is enabled and clocked by SYSCLK/12 following any reset. If a system malfunction prevents user soft-
ware from updating the WDT, a reset is generated and the WDTRSF bit in RSTSRC is set to 1. The state of the RSTb pin is unaffected
by this reset.
10.3.8 Flash Error Reset
If a flash read/write/erase or program read targets an illegal address, a system reset is generated. This may occur due to any of the
following:
• A flash write or erase is attempted above user code space.
• A flash read is attempted above user code space.
• A program read is attempted above user code space (i.e., a branch instruction to the reserved area).
• A flash read, write or erase attempt is restricted due to a flash security setting.
The FERROR bit is set following a flash error reset. The state of the RSTb pin is unaffected by this reset.
10.3.9 Software Reset
Software may force a reset by writing a 1 to the SWRSF bit. The SWRSF bit will read 1 following a software forced reset. The state of
the RSTb pin is unaffected by this reset.
10.3.10 RTC Reset
The RTC can generate a system reset on two events: RTC oscillator fail or RTC alarm. The RTC oscillator fail event occurs when the
RTC missing clock detector is enabled and the RTC clock is below approximately 20 kHz. A RTC alarm event occurs when the RTC
alarm is enabled and the RTC timer value matches the ALARMn registers. The RTC can be configured as a reset source by writing a 1
to the RTC0RE flag in the RSTSRC register. The RTC reset remains functional even when the device is in the low power Suspend or
Sleep mode. The state of the RSTb pin is unaffected by this reset.
EFM8SB2 Reference Manual
Reset Sources and Power Supply Monitor
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