Networking in embedded systems using Bluetooth
Many devices have Bluetooth connectivity available, from phones to headsets to input devices. Let's see what we can look at with this interface.
Bluetooth basics
Bluetooth is a radio protocol that operates between 2.4 and 2.48 GHz. It is not easy to sniff because it is transmitted by hopping on multiple frequencies pseudorandomly (depending on the address of the master device) and has several variants:
- BT/1.x (2000), also known as the ancestor: This has not been deployed in new products for a long time. It had privacy problems since it was sending a unique ID over the air.
- BT/2.x (2004), also known as classic Bluetooth: This has been around for years and is "kind of" kept in the hands of the big players of the market. This is the doing of Apple since, to be able to be used by iPhones, you have to send an entry ticket to them (called the MFi). It is faster than BT1 and introduces a better pairing system...