Hello @tomato,
You need to enable the clock of SWM first, to make a change in PINENABLE0 register. After you finish the configuration of the SWM module, it is recommended to disable the clock.
RaulRomero_0-1672245692864.png
[LPC84x User Manual. Chapter 10: LPC84x Switch Matrix (SWM)]
RaulRomero_1-1672245692868.png
[System clock control 0 register SYSAHBCLKCTRL0]
Here is an example for the configuration:
RaulRomero_2-1672245692870.png
Best regards, Raul.