moving from Uno to Mini Pro, vcc


I’m inexperienced so please forgive me if the answer to this question is too obvious.

I’m moving a project I was prototyping from my Uno to a mini pro. I was using a breadboard with the Uno and had an RFID reader and a photoresistor both drawing power from the 3.3v pin and it was working as i wanted.

I will be soldering wires now and have no idea if I solder a patch for each of the RFID and photoresistor into the vcc pin (so, two wires on one pin) or, if i need to achieve this differently.

I’d be grateful for some advice or a link to where I might learn more. Everything else seems more or less straightforward to me.


Is the promini running at 5V? Where will 3.3V come from? If running at 3.3V, the regulator is only good for 150mA.

i can get a 5V mini if that's preferable.

I appreciate your response here, CrossRoads. If i did have a 5v? what would my next best step be?

Please and thanks

If it's a 3.3v pro mini, use Vcc - BUT be aware of the 150mA limit.

If it's 5v, or you need more than 150mA, you need an external LDO regulator.

If you mean you are going to solder components to the Pro-Mini I don't advise it. The standard convention for uP is to have a connector (preferably a Phoenix screw connector) and an interface cable and a separate prototype perf board. Everything that is not part of the factory made Pro-Mini gets installed on the prototype perf board (or custom PCB) and the interface cable from the peripheral board (the added board) is a ribbon cable that has female headers that simply plug into the male header pins already on the Pro-Mini (assuming you installed them) . You should start your post with a photo of your Pro-Mini and a list of what you want to add to it and how you planned to do that (where you planned to install the added components).

DrAzzy and Raschemmel,

Thanks for these posts. I will receive my pro-mini in the mail soon i hope. I can then add more info but perhaps I can start this convo by adding a pic of what i have working on my Uno. I just want to solidify connections so I can ultimately compact and protect things. It's for an art installation that has to run all night so, from my understanding, a pro-mini is a better choice for that kind of job than an Uno.

As well, i'll likely make a back-up or two. I can see staging the piece again at some point but, for sure it must be able to run for 24 hrs connected to a PC.


Interesting point.

We are telling people you cannot use the auxiliary regulated 3.3V from Unos, USB to TTL converters and the like to power sub-assemblies such as the ESP8266 or RC-522 RFID boards, yet I see YouTube videos demonstrating exactly that with apparent success.