After a POR, when the boot process
completes and the CPU starts the application, the initial device conditions are as
follows:
- The NRST pin is configured in
NRST mode
- Serial wire debug (SWD) IO
are in SWD mode
- All other configurable I/O
pins are high impedance (Hi-Z)
- Peripheral modules are reset
as described in their respective chapters of this manual
- The device is in RUN
mode
- MCLK is sourced from the internal SYSOSC
at base frequency (24MHz)
- LFCLK is sourced from the
internal LFOSC (note that LFOSC requires time to start up before LFCLK can
be used)
- MFCLK is disabled
- Peripherals are disabled
- Any flash sectors configured
to be write protected at boot are write protected