I've been working my way throw the usb documentation and writing my own usb host lib (learning exercise).

On page 271 it states that register HcHCCA Quote:"Contains the physical address of the host controller communication area." But if I search the docs there is only one other reference "HcHCCA register points to Interrupt and Isochronous Descriptors List" If I search for 'communication area' I get an in depth description for the USBUDCAH register.

My best guess is that HcHCCA is for host mode and USBUDCAH for Device mode, is this correct?

Anyone know if there is a description of the structure of the memory the HcHCCA reg points to?

Ta, richard. :)

The LPC1768 USB host controller implements the OHCI standard, that's where all the names come from. The linked page has all the definitions, but I would also recommend reading the datasheet for ISP1761 (which is basically the same IP block as in the 1768) and this app note by Renesas, which reportedly fixes many bugs of the original spec.

Thanks for the links, I'll have a read tomorrow. :)