The maximum clock frequency that can be used with the internal oscillator is 16 MHz.
To configure the watchdog timer to reset the microcontroller, set the WDPG bit in the WCR register to 1, and then set the WDV bit to 1 to enable the watchdog timer. The watchdog timer will then reset the microcontroller if it is not reset or disabled within the timeout period.
Yes, the UART can be used in asynchronous mode with a baud rate generator. The UART baud rate can be generated using the internal clock or an external clock source.
To enable the brown-out reset (BOR) feature, set the BOREN bit in the PDRUNEXT register to 1. This will enable the BOR circuit, which will reset the microcontroller if the supply voltage falls below the programmed threshold.
The maximum current that can be sourced or sunk by the GPIO pins is 20 mA per pin.