When you pair your micro:bit via the official app, you may get asked to input a pattern or a PIN depending on the pairing protocol used. There are 3 possible settings which you can configure in the Project Settings of the Javascript Blocks Editor ; no pairing required (you can just advertise bluetooth services and connect), JustWorks pairing(which will ask you for a pattern) and Passcode pairing (which will ask you for a numeric code).


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Whichever method you choose, when pairing via the app, a tick on the LED screen means you have successfully paired. You will then need to reset the micro:bit and re-enter pairing mode to flash the code.


Another way to check Bluetooth is working is to use the NRF connect app to see which services are running. To do this, write a program with some  bluetooth services enabled 'on start' and set to No Pairing Required then download to the micro:bit and connect to it with NRF connect. You should see the services that you enabledin the program, visible in the app.


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