Update ble_midi_simplein.py

[spridget]

• Only connect to MIDIService devices
• Pair with the device once it's connected
• Connect the paired device to the MIDI instance

[tannewt]

Mind making this a separate example since it adds central functionality? As-is it is a peripheral that gets connected to.

[spridget]

As I understood it, ble_midi_simpletest.py and ble_midi_simplein.py are opposite ends of the same connection. The updated simpletest is a BLE advertiser that waits for a connection and pairing before starting to transmit MIDI commands. The updated simplein is a BLE scanner that looks for a BLE device advertising MIDI service, and upon seeing one connects to it and pairs, then prints the MIDI commands that come in with a timestamp.

Upon review of the original simplein I see I was wrong in my assumption. Before my changes it would wait for a connection without caring whether or not the requester was a MIDI device, then print any MIDI commands received.

It would indeed be appropriate to make this yet another example for the Adafruit BLE MIDI library. It should be noted in the new example and in simpletest that they are opposite ends of the same connection.