Hi I have tried using these blocks in an ADAU1701 without any apparent success, In desperation I went hunting for any documentation but there is NONE!! not even in http://wiki.analog.com/resources/tools-software/sigmastudio/toolbox
I am actually very interested in using these blocks instead of having to create one from scratch, so a useable description would be very helpful
Many thanks in advance
I'm afraid that what you're saying about the documentation is substantially true. ADI stopped updating SigmaStudio's built-in help files some time ago in favor of the wiki, yet even this has fallen behind. I suspect there's several difficulties:
Hopefully the docs issue will resolve someday. In the meantime, try searching EZ for user-provided docs and applications. I've tested and reported on a few function blocks myself -- either because I needed them, another user needed them, or just for fun. Any user can update the wiki (just as with Wikipedia), but I publish my reports here because they count toward points in EZ (it's that old saying: "What gets done is what gets rewarded."). When all else fails, do what you'd likely do with an unfamiliar C function -- code a simple project around the block in question, try it out, and see what it does.