Hi Angus,
This page and the pages on the bottom are an aggregation of the experiments I've made with the lwIP IP stack.
For raw TCP you can try to extend this or this demo code. These are two experiments from me (It's not a stable API, and might change).
If you want something easier try to use the HTTPClient or HTTPServer. I guess they might be able to do the trick for you as well. And I try to improve them over time.
If you want to have a play with lwIP directly have a look here and here. This is the direct callback API for lwIP.
If you discover the API (api.h) documentation from lwIP, throw it away. I did not port this API to mbed due to a lack of a scheduler on the target (FYI).
I hope this might help you.
Don't hesitate to write again if you have any explicit problems.
Regards
Rolf
Can anyone direct me to any documentation describing how to use (easily) the lwip stack?
trying to setup a tcp connection with a pc to exchange data...
thanks