Pro Micro no power on RAW and VCC

Projects General Guidance
1

Helllo,

I am trying to use the RAW and VCC pins of a Pro Micro for powering a nodemcu. Somehow I get absolutely no power from those pins. I tried it with LEDs.

Do I have to activate these pins somehow? Is there anything special I have to config in under tools in the Arduino IDE?

Thank you!

regards
p3ppi

2

That is what I would expect, they are power input pins. Try this link for an explanation of the pins: ESP8266 pinout reference and how to use GPIO pins

3

RAW is input pin. VCC is not designed to deliver power to another Devboard.

4

@p3ppi, welcome.

How do you power your ProMicro? Which ProMicro are you using (5V/16MHz or 3.3V/8MHz)?

Your topic has been moved to a more suitable location on the forum. Introductory Tutorials is for tutorials that e.g. you write, not for questions. Feel free to write a tutorial once you have solved your problem :wink:

5

I am using the Pro micro with ATmega2u4 and 5V power via USB. I am following a tutorial uses the RAW of the Micro and VIN on the esp as it only takes 3.3 Volts. But for me it does not seem to work. I measure 0 volt output on the RAW pin of the Micro

6

So we need a full schematic diagram of how you have connected things, and a link to the dodgy "tutorial" from which you are working. :face_with_raised_eyebrow:

7

This thread:

https://forum.arduino.cc/t/pro-micro-power-3-3-or-5-and-whats-this-j1/507848

has a schematic of the original Sparkfun Pro Micro. If yours is the same circuit, the RAW pin should be one diode drop below your USB supply voltage. If you get zero volts there, then your Pro Micro clone must have a different circuit.

Edit: If you also get zero volts on Vcc, and the Pro Micro still runs, then something is probably wrong with your meter.

8

Indeed it does!

9

Based on the schematic in post #8 and powering via USB

  1. No power on Vcc would mean that the solder jumper is not soldered.
  2. No power on RAW would indicate that D2 is missng or broken.

If both are true (as you state), the 32U4 does not get power and the board should not be recognised by your operating system.

10

@gilshultz :

Not according to the schematic for the pro micro.

Here is a clearer schematic:

1720×970 153 KB

Shows the USB provides UVcc.

The RAW is generally around 0.3V less than UVcc because of the voltage drop across D10
4.7V is too much for a nodemcu.
Vcc MAY be OK if the Micro is a 3.3V

11

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