How to tell 3.3V from 5V ProMini

@ronalex4203

Get a magnifying glass and check the voltage regulator on the mini. It should probably have a margin that includes ...50... or ...33...

If the regulator has 50 on it, then it's a 5.0V, else its a 3.3V

If you can't read the number, use a 9V battery to put +9V on the RAW pin and ground the battery on the mini. Then use a multimeter to measure the voltage at vcc.

I have my glasses on, one of those magnifying head band things with a light, AND a magnifying glass in between. I know there is writing on a couple things but can't read it. I did just find one chip with a 5 on it, both boards in one bag have that, the other pair have a 0. Your other approach is different than what is in your email, +9V on the

[email says VIN] [reply ^ says  RAW] 9V -ve on the mini Ground, measure at VCC.

So I am learning something here. What you are saying is the board has a builtin voltage regulator, give it 9 and it will regulate to what it wants. So why do we bother sticking a regulator in front of the board, I am now really confused.

Posted by: @ronalex4203

I have my glasses on, one of those magnifying head band things with a light, AND a magnifying glass in between. I know there is writing on a couple things but can't read it. I did just find one chip with a 5 on it, both boards in one bag have that, the other pair have a 0. Your other approach is different than what is in your email, +9V on the

[email says VIN] [reply ^ says  RAW] 9V -ve on the mini Ground, measure at VCC.

I edited the original because the Pro Mini pin is labelled RAW and other models are labeled VIN. I misremembered the pro mini and corrected the label in the post after I had I checked it.

So I am learning something here. What you are saying is the board has a builtin voltage regulator, give it 9 and it will regulate to what it wants. So why do we bother sticking a regulator in front of the board, I am now really confused.

If you have a nice clean source of 3.3V or 5V you can connect it directly to the VCC pin and feed the correct voltage directly. But, on the other hand, if you want to power the board from a 9V battery or a couple of LIPOs, then you can connect the anode directly to the RAW pin and have the Arduino make it's own VCC supply.

Note that if you supply 9V or 12V to the RAW pin that the Arduino has to manage the extra power loss from the voltage conversion, so it's harder on the Arduino in the long run. There's always a trade-off 🙂

Also, the power loss will probably be much larger when using a regulator on a chip as opposed to a buck regulator.

@will Ok, that makes sense. I will do that test tomorrow, I am fairly fuzzy headed right now and I have to solder the headers on. First time in decades doing some delicate soldering. BTW, a fellow I know from the Parksville Makers club sent me a link to a thingiverse box project. Still uses OpenSCAD but it's a much more complicated box with heat vents, multiple dials and display openings. I have the stl file for the box I want, now I have to figure out what size I want for 8 to 10 Pi 0 MotionEyeOS devices, then maybe 10 or so motion detectors.

Thanks for the lesson!

Posted by: @ronalex4203

BTW, a fellow I know from the Parksville Makers club sent me a link to a thingiverse box project. Still uses OpenSCAD but it's a much more complicated box with heat vents, multiple dials and display openings.

Yes, I've written one of those as well, allowing you to make slots in the sides, circular and rectangular openings, platforms and so on in the front and back. Very nice but also much more labour intensive to use.

What you needed was a way to make a fast, properly sized box with a lid and I gave you the easiest one I have. 

You will undoubtedly learn to adjust the sizes and customize it. OpenSCAD works primarily be adding and subtracting simple geometric shapes, spheres, cubes, cylinders and so on. It's a very primitive system but it works the way I think and I don't need smooth corners or gussets or fillers, just minimal design.

Eventually, you may want more and migrate to other software but OpenSCAD will let you learn the basics just by sitting and playing with it.

As far as possible, do things by parameters by setting a variable to represent values and make them dependant on others as much as makes sense. That'll make it much easier in the long run to change sizes and relative positions without having to rewrite large portions of code.

The box is a fair example, all of the construction is based on just a few part sizes declared at the beginning and all of the other calculations are done based on those values. No "magic numbers" in the modules that make the case and the lid, but everything lines up - even the screw holes when you change the box size.

@will I doubt I will need to play much with it. I might need some standoff ability for the cameras, but just setting regular standoffs in hot glue will suffice. If I need a hole I will drill it. For now I have to wait about a week for more parts to show up so I can begin building. 

@ronalex4203 

So you have a week to fool around 🙂

You can use a copy of the box script to practise adding standoffs and holes as required and use OpenSCAD as a prototyping tool. It's often handy to be able to rotate something you're designing and moving closer and farther away to help visualize the end product.