
System modules
STM32W108CB, STM32W108HB
Doc ID 16252 Rev 3
The Power Management module allows a special emulated deep sleep state that retains
memory and core domain power while in deep sleep.
6.2.2
Reset recording
The STM32W108 records the last reset condition that generated a restart to the system.
The reset conditions recorded are:
●
POWER_HV
Always-on domain power supply failure
●
POWER_LV
Core or memory domain power supply failure
●
RSTB
NRST pin asserted
●
W_DOG
Watchdog timer expired
●
SW_RST
Software reset by SYSERSETREQ from ARM Cortex-M3
CPU
●
WAKE_UP_DSLEEP
Wake-up from deep sleep
●
OPT_BYTE_FAIL
Error check failed when reading option bytes from Flash
memory
All bits are mutually exclusive except the OPT_BYTE_FAIL bit which preserves the original
reset event when set.
Note:
While CPU Lockup is marked as a reset condition in software, CPU Lockup is not
specifically a reset event. CPU Lockup is set to indicate that the CPU entered an
unrecoverable exception. Execution stops but a reset is not applied. This is so that a
debugger can interpret the cause of the error. We recommend that in a live application (i.e.
no debugger attached) the watchdog be enabled by default so that the STM32W108 can be
restarted.
6.2.3
Reset generation
The Reset Generation module responds to reset sources and generates the following reset
signals:
●
PORESET
Reset of the ARM Cortex-M3 CPU and ARM Cortex-M3
System Debug components (Flash Patch and Breakpoint,
Data Watchpoint and Trace, Instrumentation Trace Macrocell,
Nested Vectored Interrupt Controller). ARM defines
PORESET as the region that is reset when power is applied.
●
SYSRESET
Reset of the ARM Cortex-M3 CPU without resetting the
Core Debug and System Debug components, so that a live
system can be reset without disturbing the debug
configuration.
●
DAPRESET
Reset to the SWJ's AHB Access Port (AHB-AP).
●
PRESETHV
Peripheral reset for always-on power domain, for peripherals
that are required to retain their configuration across a deep
sleep cycle.
●
PRESETLV
Peripheral reset for core power domain, for peripherals that
are not required to retain their configuration across a deep
sleep cycle.