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Topic: Are all grounds the same? (Read 296 times) previous topic - next topic

corry_g

I am using the Arduino UNO (ELEGOO) for a project and noticed that there are 2 GND ports on the powering side with the Vin and 5v and 3.3v out, and one near the PWMs. I am wondering if all of these are the same and if I can use the one on the PWM side as a normal ground? Thanks! 

Grumpy_Mike

All the grounds on a single board are exactly the same.

terryking228

#2
Dec 04, 2020, 02:57 am Last Edit: Dec 04, 2020, 02:58 am by terryking228
Hi corry,

The Printed Circuit Board of the Arduinoo UNO (And all clones or derivatives as far as I know) have one layer that is "Ground".  So a pin (or socket, depending on the soldered-in connector) COULD be designed in almost any location that does not interfere with some component. 

I was frustrated, early on, with the 3 pins for Ground.  Several years ago, an acquaintance in China named Xiao made an early "Shield" he called a "Sensor Shield". It had 3-pin connectors for many of the Arduino signals.  Plugging a Sensor Shield on top of an Arduino made it  A LOT easier to connect multiple sensors and actuators. 


The three pins are in the sequence Ground-Voltage-Signal (GVS) the same as servos. You can just plug in servos and many different sensors and actuators.  There are 3-pin cables that make that easy.

See: SENSOR SHIELD HERE.  The second photo there shows my favorite solution.  I have an Arduino Derivative called "RoboRED" (often used on robots) made in China and I REALLY like having more than 20 GROUND pins!

DISCCLAIMER: NOW I'm showing stuff from my SHOP!!!

You can see the latest version Here: https://arduinoinfo.mywikis.net/wiki/YourDuino-RoboRED
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

Southpark

#3
Dec 04, 2020, 03:10 am Last Edit: Dec 04, 2020, 05:27 am by Southpark
I am using the Arduino UNO (ELEGOO) for a project and noticed that there are 2 GND ports on the powering side with the Vin and 5v and 3.3v out, and one near the PWMs. I am wondering if all of these are the same and if I can use the one on the PWM side as a normal ground? Thanks!
The members in this thread answered the question already - as in all those GND pins are grounds.

Also, when working with electronics - a multimeter can be super helpful and handy for electronics circuit testing work. If you happen to have a multimeter, then you can remove power from the arduino, and then find all the GND pins on the arduino ------- and a multimeter can help you to see whether those GND pins are indeed electrically connected together ----- ie. a relatively low resistance is expected to be measured when measuring resistance between pairs of 'GND' pins ---- or when using the multimeter to do a 'continuity test' between pairs of pins.

Do this resistance measurement or electrical continuity check for cases where you're unsure whether two 'pins' or two nodes etc are electrically connected together (or not). And make sure electrical power is completely removed from the circuit before doing such checks - for safety and also to avoid destroying the circuit etc.

PerryBebbington

There's only one ground, if you doubt this go outside and look around.

myiot23

I don't wish to complicate this for OP but sometimes separate grounds are used. Typically when analogue & digital circuits share a PCB, it's not unusual for the analogue & digital parts to have separate grounds.

terryking228

#6
Dec 04, 2020, 04:28 pm Last Edit: Dec 04, 2020, 04:32 pm by terryking228
Quote
Typically when analogue & digital circuits share a PCB, it's not unusual for the analogue & digital parts to have separate grounds.
Yes.  And often those grounds are brought together at a "Common Ground Point"..

More information on all this "Where Is Ground?" subject is HERE  See section 6 particularly.

SOME systems have total isolation of digital and analog sections (often using Optical Isolation between them).

In some unusual situations, such as high-powered broadcast stations, "Brute Force" grounds are used with wide copper straps and hundreds of buried (in the Ground!) ground wires.  Personally I have 6 inch wide copper strap all the way across my cellar ceiling, connected to 3 ground rods driven into the (ground).  But I'm weird, and sometimes run radio transmitters of 250 watts or so. 

In the UK and elsewhere "Grounding" is called "Earthing".
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

Grumpy_Mike

#7
Dec 04, 2020, 05:11 pm Last Edit: Dec 04, 2020, 05:13 pm by Grumpy_Mike
Quote
I don't wish to complicate this for OP
But you are going to do it anyway. Do you imagine for a microsecond that I don't know this?
This is not what the OP asked and it is not what the OP needs.

When a beginner is struggling with what to us seem simple concepts he doesn't need information that he will not be able to understand and will not need at all for a long time.

I am dyslexic and I was greatly hampered at school by teachers telling me spelling rules only to spend the rest of the lesson telling me when these rules do not apply, instead of trying to get me to learn these rules. In good teaching exceptions are only covered when they are needed.

PerryBebbington

Which was kind of my point; you could write a book about grounds, but I think you just need to keep it simple for a beginner, hence look around outside, how many grounds are there?

Southpark

#9
Dec 04, 2020, 11:22 pm Last Edit: Dec 04, 2020, 11:25 pm by Southpark
Very true indeed. Basic circuit theory at the beginning of it is generally taught based on ideal components. Ideal wires, ideal resistors etc.

Build from the ground up hehehe

SteveMann

I don't wish to complicate this for OP but sometimes separate grounds are used. Typically when analogue & digital circuits share a PCB, it's not unusual for the analogue & digital parts to have separate grounds.
It is quite infrequent that separate grounds are used. I don't think it's anything a beginner or even average Arduino user would ever encounter.

OP- Electrically, all grounds are connected together.  If there's any doubt, use your DMM to check.
Fritzing pictures are NOT schematics. I don't speak Fritzing.

Please do not ask for help by PM. I will not respond. If you need help, post a question on the appropriate forum.

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