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Core Electronics Forum

Arduino / bluetooth product suggestion

#1

Firstly, I must confess to being an Arduino noob who is just starting to learn. However, I am helping some kids with a project over the holidays to get an Arduino board with a Pixy2 camera to talk via Bluetooth to a Lego Mindstorms EV3 robot. I need some advice on what combination of your products might work here for the Arduino / Bluetooth piece, understanding that beyond establishing the connection it will be up to us to work out how the Bluetooth messages can be passed around.

I believe EV3 supports Bluetooth 2 only so I cannot use Bluetooth 4 or BLE. From a quick scan, it looks like something like this shield (https://core-electronics.com.au/freetronics-bluetooth-shield.html) with a Uno or compatible board (https://core-electronics.com.au/uno-r3.html) could work. Would you agree? Would you suggest that I consider anything else (e.g. any Arduino boards with integrated Bluetooth 2)?

#2

Hi Grant,

I’m not too sure what sore of protocols that the EV3 uses. Could you find some project or tutorial examples from the web where they’ve got this connection made? I would be able to work backwards from there.

#3

Thanks for the reply Stephen.

My understanding is that EV3 has Bluetooth 2 support and nothing more recent is available.

I’ve been able to connect an EV3 to an mBot v1.1 via Bluetooth, send a Bluetooth message from the EV3 to an mBot and then display the bytes received by the mBot on an LED matrix. Here is some chat on another forum about this including links to other projects:
https://forum.makeblock.com/t/connecting-lego-ev3-to-mbot-via-bluetooth/9618

The byte sequence allowed me to see the message structure being used from the EV3 so I can interpret on the mBot side. We don’t want to use an mBot for the new project but figure that, given mBot is Arduino-based, what we’re looking for on the Arduino side would have similar Bluetooth support. The mBot project just proves it is possible.

Note: one annoying thing about mBots is that they have a Bluetooth name of ‘Makeblock’ and it doesn’t appear that you can it, making it difficult to connect to more than one at a time. We would want to be able to change the Bluetooth name on the device we use in our new project so there is no chance of conflicts.

#4

Hi Grant,

I would think that you would be able to connect to Arduino with an HC-05:

They are low cost and interfacing with an Arduino Uno is well documented. Check out these tutorials:


As far as connecting to your EV3 goes, you are moving into uncharted waters it seems. I’m not sure what advice I can offer there. If you do work out a solution you’d be doing a service to the maker community by sharing your findings :slight_smile:

#5

Hi Stephen,

I had scanned the info before making the original contact. I understood that we could use a HC-05 but then we would have a bunch of wires as well as other complications (voltage differences) to sort out. It seemed that the Freetronics Bluetooth Shield has a HC-05 built-in, fits on an Arduino board with no wires and sorts out voltage difference. A little more expensive but less hassle. I just wanted to confirm my understanding as less hassle when you are a noob is a good thing. I think we have enough adversity ahead of us attempting the EV3 connection!

So, please verify my understanding on the Freetronics Bluetooth Shield as I think this is the way for us to go.

#6

Yes that should work just fine! You could even go one step simpler and get an Arduino Compatible board with Bluetooth built in:

#7

Thanks again. My quick scan indicates that Bluetooth 4.0 is backwardly compatible with Bluetooth 2.0 (what the EV3 supports). Given the mBot is relatively new and its Bluetooth chip is likely to be 4.0, I’m guessing this is all OK.

It also has the ICSP pins that we would need to plug the Pixy into.

Therefore, the Bluno looks like an attractive all-in-one package but I’m a little concerned that despite it being fully Arduino compatible, it does have differences (https://www.dfrobot.com/wiki/index.php/Bluno_M3_SKU:DFR0329#Differences_between_Bluno_M3_and_Arduino) as well as a custom Arduino IDE. This makes me think that if we get stuck, the amount of support that we might be able to get could be limited as it is a little bit different to normal. Again, with limited experience, are we better to go the standard path or do you think the the Bluno differences are not significant for what we are considering?

#8

Hi Grant,

The Freetronics Bluetooth shield would likely have the least amount of complexity for setup. Its essentially the HC-05 as a shield. Even though it wouldn’t be so tight of a package I would still personally go with the HC-05 and some jumper wires. That said, you will get the same functionality from both. The only other factor we haven’t yet considered is that it takes 14-21 days for us to get those Freetronics shields in, and the HC-05 ships same day :slight_smile:

#9

OK, I’m convinced - I’ll try a HC-05 with a board first to see if I can get it to work. I can always move to a shield if I prefer later. What could possibly go wrong? :slight_smile:

#10

The HC-05 is the most common Bluetooth Antenna there is. You will find a ton of resources on how to use it, and if you run into any problems you can just ask me here!

The shield is always an option later on, the HC-05 is low cost enough that it can be replaced without being wasteful. Plus that would free it up for your next project! :slight_smile: