I am making a basic project that will have 4 or 5 arduino nodes. Each arduino will have a bluetooth module attached. The thing I want is, I want to be able for each one of these arduinos to know the other is present in the room (let's say, 5 meters). For my experience in the cellphone, I don't even have to pair bluetooth devices to know about their presence, as long as they are in visible mode. Since I just need to know their presence, and no exchange of information will ever happen, I probably will never have to pair them right?

For this project I need a bluetooth (BT) module that:

1) Enables me to change the ID of each arduino, so that, even if I use my cellphone to scan for BT devices I will see (Arduino1, Arduino2, etc...) instead of default-factory-names.

2) Enables me to scan around for existing devices every time each X seconds, because I want each arduino to know if the others are in the room.

Will this module do the trick? http://www.ebay.co.uk/itm/Interface-Base-Board-Serial-Transceiver-Bluetooth-Module-For-Arduino-UNO-R3-/111482008102?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item19f4d87226

Later I will probably hang around with batteries so I will want a low power BT module, having the same 2 capabilities mentioned. Will NRF8001 do the trick for me? http://www.nordicsemi.com/eng/Products/Bluetooth-Smart-Bluetooth-low-energy/nRF8001


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    This is not even remotely an Arduino question, but rather one which belongs on EESE. – Chris Stratton Jan 21 '15 at 17:37

From skimming that post, I believe that your linked pcb is not a full bluetooth module (note how there is no bluetooth chip or antenna of any kind). This is simply a "base board," which is why it is so cheap1.

You will need something like this that actually has the components you want.

To answer your questions:

  1. The bluetooth library for arduino sets the discoverale name to ARDUINOBT by default, but that can be changed in the setup() method.
  2. "scan around" is a little ambiguous—AFAIK, bluetooth can only connect to one device at a time, but I'm not sure if that's totally true. You may want to look into using radios instead of BT, as they can communicate more freely with one another, are extremely cheap, and have extensive arduino libraries availible. I'm currently working on a project that uses the nRF24L01, and I'd be happy to answer any questions you have about it.

1: It also has a draw of 6v VCC, which is more than the Uno can output.

  • Also, I believe this arduino forum post is talking about the same exact boards. Lots of information there if you're interested. – afischer Jan 21 '15 at 12:34
  • I have the idea that while you are scanning for other devices no connection is being made (correct me if im wrong). In that case I won't even make a connection. I am just interested in the part where you scan for visible devices. Like what you do on your phone: motorola-global-eng.custhelp.com/rnt/rnw/img/enduser/… I am interested in that list which shows the devices that I can connect to (but I won't connect because I only want to know their presence and that list is enough for that). – nemewsys Jan 21 '15 at 13:11
  • Ah, sorry I misunderstood. Yeah, I'm pretty sure there's a bluetooth library with functions to get an array of available devices to pair to. You would simply then need to write a sketch to print that array to serial or display it in some way. Check out the various bluetooth libraries people have created for arduino—a quick google search should give you a whole bunch. – afischer Jan 21 '15 at 14:12

The first link is for a breakout board only - it has a placeholder for a BT module, similar to the HC Bluetooth models series, but it is not a complete Bluetooth board (hence the "Interface Base Board" in the product's title). Please do not do that mistake - I did it already :)

For your purposes, it seems that something similar to the cheap HC-05 can satisfy both requirements: You can change the device name, and perform inquiry to scan other Bluetooth devices' MAC address, both using AT commands.

It has low operation voltage (1.8v-3.6v), but it operates as the good-old 2.1 Bluetooth standard, which waste a LOT of energy while running. If power consumption is a prime requirement, you might want to consider the more expensive Bluetooth low energy, such as a breakout board for the chip you suggested (the NRF8001).


Should've been a comment, but...

First of all, your questions 1 and 2: yes, that can be done.

I'd go for a HC-05 just like Omer suggests. And if you want to pair them, it is perfectly possible to pair one master with several slaves. Depending on implementation, a slave can connect to several masters too. The HC-05 can switch between these modes.

You can't do it with a NRF8001, as this is a BLE slave device only, it won't do scanning. Try to find a device that can do both, like BLE mini.

You can't mix BLE and Bluetooth devices for this, it's either or.

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