Thanks for your help, including printf into the Serial class (AVR). sprintf will not do everything desired (%f,%s,%e).
Yes it does. You have not been paying close enough to the discussion details.
The AVR libC library includes multiple versions of the xxprintf() library code.
The different versions of the xxprintf() library code have different capabilities.
All of them support %s - not sure why you think it doesn’t.
The one linked in by default does not support floating point formatting.
To select a different version of the xxprintf() library, you have to change a linker option.
And that is why several of us were talking about having to modify the platform.txt file.
All this has been brought up more than once in this thread.