Pro Micro ATmega32U4 5V 16MHz voltage from VCC pin

Other Hardware 3rd Party Boards
1

I am a newbie so would be grateful of any help
I purchased 10 pro micro boards from aliexpress for a project I am building.

This is the full description of the items I bought
Pro Micro ATmega32U4 5V 16MHz Original Chip Replace ATmega328 For Arduino Pro Mini For Leonardo UNO R3

I wanted to program them to run a rotary encoder which requires 5v. I should also mention they would be connect to a pcs USB port at the time.

I thought these boards vcc output should be 5v. But after having problems I tested the vcc and was getting 3.3v I contact the supplier but was told I had tested it wrong. Can someone please confirm if I should be getting 5v from the vcc pin or if I am doing something wrong.

I will include 2 photos 1 with me testing it and 1 of the board if you need any more info just let me know.

microproboard
microproboard1105Ɨ564 137 KB

microprotest
microprotest970Ɨ870 95.1 KB

Thank you for any help
Cheers Mike

2

Welcome to the forum

To quote from the results of a Google search

The Arduino Pro Micro is available in two versions: 3.3V and 5V, and the operating voltage determines the maximum allowable voltage on the I/O pins:
3.3V: Runs at 8 MHz, which is half the speed of the 5V version. The supply voltage (VCC) is 3.3V, and the supply voltage (RAW) is 3.6Vā€“12V.
5V: Runs at 16 MHz, and is similar to an Arduino Leonardo.
Arduino Pro Micro Pinout, Power Supply and Brief Schematic ...
You can check the back corner of the board to determine which version you have. One of two boxes should be checked to indicate the operating voltage.

3

Have a look at the voltage regulator and crystal.

image
image997Ɨ505 54.2 KB

1 Like
4

Hi Mike,

Looks to me like you are testing it right and you have 3.3V version.

Show a photo of the underside of the board. Sometimes there are "3V3" and "5V" printed there and one might be checked.

Are you sure about that? Most rotary encoders don't care about voltage, they are just switches. Post a link to your encoders.

5

Thank you so much for taking the time to reply.
I tried taking a photo of the items you circled but couldnt get a clear enough photo
So here is what it says on the one chip it says
SCTF
16.000
and on the other chip it says
AAEU
NAQ1

Hope that helps. I would just like to know if I have been sold the one I ordered and if the order is correct which one should I have ordered to have 5v from the VCC

6

Hi Paul Thank you so much for your reply.
I will leave a photo of the underside.
The project I was trying to make you can see here.
project

and the encoder this project uses is the same as this one
Encoder

and works between 5v and 24v

board back
board back787Ɨ430 95.5 KB

Cheers Mike

7

So you have 16MHz(5V) version with wrong voltage regulator. That error has been discussed here on this forum as well.

If I'm not wrong, closing the jumper J1, should bypass the voltage regulator and connect usb 5V to Vcc.

2 Likes
8

No clues there then :frowning_with_open_mouth:

So it seems these boards are from a batch with a manufacturing error. You could ask for refund.

Otherwise try @kmin's advice and close that jumper.

Ok, that appears to use optical encoding, rather than mechanical, so will need a supply voltage for its illuminator LEDs.

9

Thank you so much I have bridged the J1 jumper with solder and I am now getting the correct 5v from the VCC pin. :grinning:
I guess its my own fault for buying cheap boards but fantastic to know I can still use them.

Thank you so much for your help.

Cheers Mike

10

Thank you so much Paul for your help. I got the full 5v by using @kmin suggestion of closing the J1 Jumper.

Cheers Mike

11

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