I need to have an iOS device send my nRF51 some commands, some settings, and retrieve some data, not at regular intervals. The nRF51 should only-speak-when-spoken-to.
I'm looking at all of the possible Bluetooth "services" and none of them seems like they are designed for this.
Except maybe HID, where I can probably use custom input and output reports for my purposes. Will this have an problems working?
Or maybe "alert notification"? I see how to get a message to the nRF51, but I don't know how the nRF51 can send a message back.
Is there another better way?