Which Arduino for this project?


This is my first Arduino project. I want to have 10 laser diodes (6mm, 5V, 5mW, each have just a red and blue wire and act like a simple laser pointer: link to the ones I’m using ). I need to be able to turn each one on and off independently of the others. I also want a bluetooth controller so that I can send commands from my Android cellphone. Thinking the HC-05? Want to go with the cheapest Arduino, so that I might be able to produce them in more bulk and still be affordable.

I’ve read comparison charts, but not really sure how many digital i/o and analog inputs I’d need for this. Would an Uno R3 do the trick, or if not perhaps a Leonardo?

Also, outside of the power supply and a case, is there anything else I’d need for this?


I'd go for the Uno R3 so that when you move towards mass production, you can buy the dip package and crystal oscillator in bulk for much cheaper than a whole board.

I think HC-05 or HC-06 will do the trick as long as you aren't trying to connect to a Bluetooth 4.0 device.

Cool, so the R3 can handle all those connections? Oh and re the bluetooth 4.0 thing...yeah I've been trying to understand that. Does that mean the HC-05 can't connect to a modern phone like say the Galaxy S8? I read that it couldn't with iPhones, but Android wasn't mentioned much.


Not sure, you need to do some more research on the S8 to know for sure.

Your Android bluetooth 4 device will talk to HC-05 but it reverts to bluetooth 2 in order to do so. It thereby loses the BT4 range and power consumption advantages. You can forget IOS if you use HC-05. I don't know why iPhone won't revert to BT2, I guess it has something internal and is as much to do with apple's need to hold you by the short and curlies.

If you want to do something commercial, it would be silly not to use BT4. Having said that, I think it would be better to develop what you intend to do with Uno/HC-05, and commercialise it later.

Ok great thanks!

Now just still trying to figure out the number of components I can connect to the Uno vs Leonardo.

What I know is:

| Device | ** Digital I/O ** | ** Analog Input** | | - | - | - | | Uno R3 | 14 | 6 | | Leonardo | 20 | 12 |

What are the laser diodes considered? Are they a digital i/o? If so, does each one consume 1 digital i/o (such that 10 laser diodes uses 10 of the 14 digital i/o's)? Same question for the bluetooth module.

Thanks again!

I think I've figured out my answer. They're each considered 1 digital i/o. Thanks

If your figuring out involves getting a Leonardo, you might just check out on what they mean by 20 digital pins, as I believe it has the same number of physical pins as a Uno. The principle differences between it and a Uno are that it can look like a USB device to a PC, and I believe more pins can be used as analogue. I doubt either of these are of interest, and Uno is the obvious choice, but if you feel you will need to expand things in the future, you will be better off with a Mega. Bluetooth simply sits on pins 0,1 as marked on the board, and Uno’s analogue pins can be used for digital signals.

Ahh interesting. Thanks. I already ordered the Uno, but if I have good success with it and just need more connections I'll get the Mega. Thanks again