Howdy - The pinout for the Pro Micro shows 3 pins labeled "GND": [ProMicro] Pins 3 and 4 (counting down from J1), and pin 23 (right before the "RAW" pin on the other side) are all labelled "GND" - but I think the are not the same. If anyone is willing to agree with me and state that "they are n…

[image] dbw3: all labelled "GND" - but I think the are not the same. I think the onus is on you to back up your claim, not expect others to do so.

[image] Arduino Pro Micro support in IDE 2.0 IDE 1.x I'm considering to use the Pro MIcro as a drop-in for Teensy 2.0. It uses the same 32U4 MCU with embedded USB interface and has a somewhat larger foortprint than Teensy. When I select the Pro Micro/Mini in t…

Just the basic "probes on the chip" type... They're not the same electrically - which I believe means they were intended to serve different functions.

To be clear, are you saying you used an ohmmeter, and measured more than, say,1 ohm of resistance between the GND pins? If so, the first thing I would suspect is a poor solder joint on one of the pins. Are they pins, and are they soldered in, or were you measuring the pin hole to pin hole, before …

Pins are all soldered in. I checked several (3) of my protoboard units, and they all show the same characteristics - including one that I just removed from the packaging about an hour ago. I'm certified "Hi-Rel" soldering (and wire-wrap, too !!!) so, my joints are good. I appreciate your help - l…

[image] camsysca: To be clear, are you saying you used an ohmmeter, and measured more than, say,1 ohm of resistance between the GND pins? Sorry, but…

Oh! I'm the sorry one. Yes, more than 1MegOhm. I will tell you that 2 of the three pins read a dead short to the USB connector's outer "shell" but not to the third pin - and one more thing: I only paid about 5 USD for each of these on Amazon - so probably not original Arduino equipment. I also ha…

We do believe you. Now, trace the unknown ground pin back to some chip and tell us what that is.

GND is GND is GND, there’s 3 of them. Use any or all of them you want. Just like Pro Mini, Pro Micro is a Sparkfun product. Get the official documentation from Sparkfun.com , including the schematics, Eagle files, and other information. Pro Mini got an “endorsement” or blessing from Arduino …

See the schematic: https://cdn.sparkfun.com/datasheets/Dev/Arduino/Boards/Pro_Micro_v13b.pdf So I can't agree with you that they are not the same. [image] dbw3: It should be well documented on the official site, Which official site?

Pro Micro GND pins - different?

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van_der_decken February 7, 2026, 11:18pm 2

I think the onus is on you to back up your claim, not expect others to do so.

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Pro Micro GND pins - different?

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