To enter Pairing Mode on the micro:bit you'll need to hold down the A, B and reset buttons simultaneously, then release the reset button once the LED screen has filled and you see the Bluetooth logo.
Ensure you have flashed a new/recently created HEX file to the micro:bit created in makecode.microbit.org. It doesn't necessarily matter what the program does, but a new file will contain the latest pairing process as part of the HEX.
Using the Android App, developed by Samsung you will be walked through the pairing process step by step, but for reference here is a short video of the process. There is a step by step walkthrough on pairing in Android in another article.
Using the iOS app, developed by Insight Resources you will be walked through the pairing process step by step, but for reference here is a short video of the process.
There is a MakeCode experiment that adds support for Bluetooth flashing, however it is still in development so there may be a few issues with it. More information can be found here: https://github.com/Microsoft/pxt/issues/4807
How to enable it?
- Open a browser that supports Web Bluetooth. See https://caniuse.com/#feat=web-bluetooth. On Windows, you'll need Chrome 70+.
- Open MakeCode (https://makecode.microbit.org/)
- Go to the gearwheel menu and click on
- Select your device and pair
- Press Download to start remote flashing.
If you cannot see that button and you editor supports this experiment, go to About, then click Experiments and Bluetooth Download. If you cannot see this card, your editor does not support yet this feature.
If you can't enter pairing mode, check that you have a uploaded to the micro:bit