Arduino pro mini external + usb ?

Hello,

I was wondering if an arduino mini pro (3.3V 16mhz) would switch power supply correctly when RAW pin and USB port are in use ?

or should I cut the 5V from usb cable ?

regards

Please review your post. A Pro Mini can work on 3.3V 8MHz or 5V 16MHz. Using the wrong voltage will cause wrong timining and baudrate. It also does not have a USB connector.

DrDiettrich:
Please review your post. A Pro Mini can work on 3.3V 8MHz or 5V 16MHz. Using the wrong voltage will cause wrong timining and baudrate. It also does not have a USB connector.

yeah sorry I forgot to mention I use and FTDI adapter of course

that does not mean the question cannot be answered

I found the schematic and it does not seem to have power switching mechanism

like described on this picture

please next time be more constructive in your criticism

appreciate

please next time be more constructive in your criticism

Come off it. You post a crap question and you expect a better answer than you got. You got a very good answer considering what you posted.

yeah sorry I forgot to mention I use and FTDI adapter of course

There is no “of course” about it, there are many ways to supply the power, not just one way, you don’t say then we don’t know. Mind reading is not a skill thick on the ground here.

I was wondering if an arduino mini pro (3.3V 16mhz)

For a start is is MHz not millihertz. Next the processor will not work at 16MHz with only 3V3, so that sentence is a nonsense.

A good (original) 3.3V Pro Mini can be powered during programming by 5V or 3.3V. Cheap clones may be damaged by 5V.

DrDiettrich:
Cheap clones may be damaged by 5V.

How?

The Pro Mini doesn't have any special power switching. If you are feeding power to the RAW pin and also to VCC via the FTDI connector or the VCC pin, then either the internal regulator or your other supply will feed the load. It doesn't know that one is preferred over the other and minor manufacturing tolerances and even the temperature of the two voltage regulators will make one supply more than the other.

@Paul: a cheap clone will have cheap capacitors. While it's rare to find a 3V capacitor that blows up with 5V applied, I'm sure the clone manufacturers are working very hard to find such a device and save a few milli-cents on each unit.

A cheap 3.3V regulator may not survive 5V on its output, as supplied by the FTDI connector.

I think a 6V5 is the smallest working voltage I have found for a capacitor.

phil123456:
yeah sorry I forgot to mention I use and FTDI adapter of course

that does not mean the question cannot be answered

I found the schematic and it does not seem to have power switching mechanism

https://www.arduino.cc/en/uploads/Main/Arduino-Pro-Mini-schematic.pdf

like described on this picture

https://www.open-electronics.org/wp-content/uploads/2015/07/Fig10-500x241.png

please next time be more constructive in your criticism

appreciate

Hi Phil,

This has nothing to do with your project, but I'm curious. What part of Dr. D's post did you find non-constructive? It seemed positive and helpful. He even said "Please".