Hello Fco. Javier Rodriguez G,
I recommend you to download the newest version available of the SDK (2.4.1) for the LPC804, instead of migrating the drivers of other MCUs. Within the SDK you will find drivers for all the peripherals, even the PLU. The drivers are really good implemented, so, you won't have any problems while working with these.

Link to download the SDK.
Hope it helps!
Victor.
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