Have just started looking into 32-bit uControllers after being around the 8-bits for sometime now. Previoulsy with devices like the atmega644 that I used only 1 pin for each function, while there may have been multiple functions for each pin, they still only used one output/input per internal component. I started looking into the AT32UC3B0128, as such the USARTn RXD and TXD pins can be used with two pins each. I understand the reason behind it, trying to maximise the amount of components to use with as much selection as possible from the pins.
My question is, are these pins grouped, set individually, or always on when I switch component on?
E.g. If I set USART 0 into one of the modes that activate the PA18 UART0 RXD pin, am I forced to use the PA19 USART0 TXD pin or could I use the PB11 USART0 TXD pin with the PA18?