Electronic – 3pi Robot with Bluetooth

Yes, this is as easy as you think it is!

Most integrated Bluetooth modules (modules that have a built-in stack, rather than HCI only which require you to use an external stack) will allow you to scan (inquire) for devices. I've been playing with several recently, the Bluegiga modules such as the WT12 have a particularly nice and easy to use serial interface. For those modules it's pretty much just a case of connecting to a UART, sending the inquire command down to the module and reading back the responses (a line per device found which includes the MAC address and device name).

Most of the modules I've seen have similar commands and interfacing. Expect to pay $20-40 for a module of this type.

Best choice depends on many factors - only some of which are range, security, amount of data required to be known, number of items to track, number of locations, powered versus unpowered, acceptable size, acceptable cost for nodes and masters, ... .

The best choice is something you haven't heard of, but we may not have heard of it either :-).

RFID

• low cost tags

• tags usually small and flat (under 1mm thick).

• relatively short range 0.1 - 1 metre typically

• longer range possible but aerial size MAY grow.

• simple tags are usually unpowered - using energy pickup from interrogator

• tag usually just has an ID but can also interact with tag to exchange fixed or variable data. If desired tag can be a processor equipped.

• Uses NFC (near field communications) - whether these work with the NFC equipped phones etc you are using is a purchasing choice.

Bluetooth:

• Typically a short range telemetry system with own powering and formal transmitter receiver.

• More complex and more capable than typical RFID tags.

• More range than most RFID but still limited. (Metres to tens of metres - more possible but not the norm).

• More expensive than typical tags

• Smallest bluetooth is probably a few cm³ volume. I may be wrong.

• Work with almost any bluetooth enabled system including many phones, laptops/netbooks/tablets, dedicated bluetooth equipment.

Other:

• WiFi: Dearer, more range, battery power, higher power drain unless custom made to poll, no practical limit to functionality.

• Custom NFC. like RFID but non standard. May be suited to some niche larger volume tasks where a need exists that std RFID doesn't address.

• Infrared: May be chosen in selected circumstances.

• Simple low cost RF transceivers- ASK and similar. Less complex and cheaper than Bluetooth. Range as desired out to say 100+ metres.Battery powered. May be system of choice in higher volume custom system. No interface with std phones or PCs without extra interfacing.

• Capacitive - just maybe. Excellent in some cases.

• Other we haven't heard of ... :-)