This seems like a good place to ask.
What I want to do is drop an inexpensive module onto a design such that when connected to linux, windows, or mobile phone (the last is nice but not essential) it presents as a serial interface such as a terminal might talk to, and that the design side of this sees merely a Tx and Rx pair at some convenient baud rate, which doesn't need to be changeable. There is no need for any great data exchange, but it must all still work if the unit isn't paired...
Not knowing what to ask on DDG, I ask here please!
(and for the mobile phone, is there a suitable serial terminal that will connect to a bluetooth 'line'? Ideally without introducing adverts or requiring access to everything including my inner leg length?)