Pranav, sorry about your name - thought I got away with that! With my surname I get a lot of that too.

I came to the conclusion that the RTOS could be made to work, but is not necessary. So as I believe in doing things the simplest cleanest way possible.

I think that if I rewrite with no RTOS, and ring buffers where necessary, the thing will work fine and be robust too. Also less code to deal with.

Still the RTOS is there and it works (although could be optimised) if there is a good reason to use it. One good optimisation would be to be able to have different stack allocation for each task - to use less stack memory.

Thansk all for the generous help received. I think I have it now.