My friend is home!
The micro:bit has bluetooth, so could be programmed to listen for connections from each person's phone. Or maybe bluetooth doesn't work like that and we need to use wifi? In which case this is harder since we'd need an external wifi chip.
- I don't think Bluetooth necessarily would send out a beacon constantly, my guess would be that it would do that when it's in seek mode, but I might be wrong. Bluetooth beacons are a thing, though, and we could write a little app which your friend turns on when they are near your door pretty easily..
- Yes, after reading up on this I think one nice solution is to have a raspberry pi in the lan (either plugged into the router or with a WiFi dongle) scanning the network periodically for known mac addresses and talking to the microbit via Bluetooth. Given that, maybe a simpler solution is to connect servos and LEDs to the pi instead. Pilchard (talk) 18:30, 20 January 2018 (UTC)
It could then display a scrolling message on its screen.
For waving the arms of a little robot, we could use a servo.
Here's an example of a microbit doing both!
Turtle and I made a game of catching falling blocks! https://makecode.microbit.org/_beiMp4PKC0hy