Pro Micro Raw pin

Hi everyone. I purchased a 3.3V version unknowingly, which means that VCC only outputs that amount. If I need 5V and I'm powering it via the USB plug, is it safe to use the RAW pin for 5V output?
Thank you

sparkfun's page states

  • VCC is the voltage supplied to the on-board ATmega32U4. This voltage will depend on whether you're using a 3.3V/8MHz Pro Micro or a 5V/16MHz version, it'll be either 3.3V or 5V respectively. This voltage is regulated by the voltage applied to the RAW pin. If the board is powered through the 'RAW' pin (or USB), this pin can be used as an output to supply other devices.

  • RAW is the unregulated voltage input for the Pro Micro. If the board is powered via USB, the voltage at this pin will be about 4.8V (USB's 5V minus a schottkey diode drop). On the other hand, if the board is powered externally, through this pin, the applied voltage can be up to 12V.

note that the current/ power you get from USB will flow through the board's circuit to the pin so don't expect to draw lots of Amps (if your USB port was capable of this) from it without damaging the PCB track and your arduino

Below is the relevant part of the schematic.


There is a solder jumper (SJ1) on the board; short it and your ProMicro will become a 5V/8MHz model.

Beware of clones that do not agree with this schematic! But are otherwise merely too cheap to believe.


Thank you J-M-L. Currently I'm using it only in two projects, but I think I'll replace this boards with some new 5V I just ordered. One of them only powers 3 hall effect sensors, so no problem there with the amperage drawn. The other one is powering a max of 5 leds (they will not be usually lit all together but eventually they might, so I would expect a max amperage of about 100mAh or less. Still, I will replace the boards. Thank you

Mine are actually clones. So much clones that they actually need to be programmed as Lillypad Arduino USB (though they have the Pro Micro shape and form)

seems you should be fine indeed.

your board might also be 8MHz, make sure this is taken into account when you upload your code

@J-M-L , it's a ProMicro :smiley: Time or coffee :laughing:

not sure I get it but I'll have the coffee :wink:

EDIT: I GOT IT... I'll go for coffee :slight_smile:

It's an ATmega32U4/8Mhz, but it doesn't really matter. When selecting the Lillypad USB board in the IDE it doesn't even request you to select a processor.

don't worry about my comment, there was no such thing as a ProMicro 3.3V 16Mhz I guess

Install the SparkFun AVR board package. After that you will have the option to select a 3.3V/8MHz ProMicro.

Yes, there are. Stupid cheap chinese crap where they put the wrong crystal on the board :face_vomiting:

yeah I guess there is no limit to this...

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