Hi,
I suppose that you misunderstand the switch matrix function.
Pls refer to the section 10.4.2 Switch matrix register interface in UM11029.pdf.
There are fixed-pin functions, the GPIO pins are fixed-pin function. Pls refer to the LPC845 with 64 Pins LQFP, you can see that the GPIO pins are fixed, for example pin4 is PIO0_12, you can NOT move the PIO0_12 to another pin. If you do not use the GPIO function for the PIO0_12, you can assign the PIO0_12 as the other function, for example uart TX or RX pins, SPI pins whatever.
The current capability feature is only related to specific pin, for example, "PIO0_10 can operate as high-current sink drivers (20 mA) independently of the programmed function", it means that the pin PIO0_10 can sink 20mA current, if you configure the pin as GPIO output function and output low, it can sink 20mA current. If you do not configure the PIO0_10 as GPIO, you set the pin as UART0_TX pin, when the pin is in low state, it can sink 20mA current. But you can not move the other pin to this pin, for example, you can not move the pin PIO1_20 to PIO0_10.
Hope it can help you
BR
XiangJun Rong
