The XRSn pin can be driven
externally by a supervisor or an external pullup resistor, see the Pin Attributes
After reset from any source (see
), the boot ROM code samples Boot Mode pins. Based on the status of the Boot
Mode pin, the boot code branches to destination memory or boot code function. If
boot ROM code executes after power-on conditions (in debugger environment), the
boot code execution time is based on the current SYSCLK speed. The SYSCLK will
be based on user environment and could be with or without PLL enabled.