Physwiz:
Thanks, but I'm after master nano to slave nanos without the mobile phone app and with master interrupt control of slave outputs
It does not need phone to control slaves using BLE. It is very helpful tool to have. Creating slave(server) - and control from phone - you know that this part is working, then creating master(client) testing using phone - then connecting both without phone app. That is the way I would do it. Otherwise is very challenging task.