Hello dav1
You can find more detailed information about the PLU at the User manual of the LPC55s6x under chapter 38 "LPC55S6x/LPC55S2x/LPC552x Programmable Logical Unit(PLU)" https://www.nxp.com/products/processors-and-microcontrollers/arm-microcontrollers/general-purpose-mc...
Also, please check these post. Although they are for LPC804 they can be useful as reference
https://community.nxp.com/docs/DOC-342087
https://community.nxp.com/docs/DOC-341477
https://community.nxp.com/docs/DOC-341656
Additionally you can find examples at the sdk of the device you are using.
Let me know if this is helpful.
Best regards,
Omar
Training videos for using the PLU Config tool are here:
https://www.nxp.com/design/training/introducing-the-lpc-plu-configuration-tool:TIP-PLU-TOOL
The PLU in LPC804 and LPC55xx devices is the same, although there are some differences in how the block connects into the rest of the device. LPC804 has the advantage of a switch matrix (which isnt feasible on a larger device like in the LPC55xx family) which enables you to make connections between the PLU I/Os through that, without having to make these connections off-chip.
You might also find this video useful for some example circuit implementations using the PLU: