Does it matter to which ground pin I connect my components?

There are a few ground pins on the Arduino Nano board. Does it matter which ground pins my components are connected to? I connected all the component's ground wire to one single ground pin on the board; the one beside the 5V pin. Would this be a bad idea, or do I have to use the other ground pins? Why would the Arduino board have more than 1 ground pins anyway?

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It doesn't matter.

There's multiple pins for convenience - because you often need more than one.

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So I can link both digital and analogue components into one single ground pin without issues, right? But if this is the case, when would I need more than one ground pin if I could just link everything all back to one ground pin?

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xEnOnn:
So I can link both digital and analogue components into one single ground pin without issues, right?

Yes.

When you design your own PCBs you're not supposed to mix analogue/digital but with an Arduino there's not much you can do (it's all connected together).

xEnOnn:
But if this is the case, when would I need more than one ground pin if I could just link everything all back to one ground pin?

More than one pin makes life easier.

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Now I see. Thanks a lot for your help!! :slight_smile:

xEnOnn:
There are a few ground pins on the Arduino Nano board. Does it matter which ground pins my components are connected to? I connected all the component's ground wire to one single ground pin on the board; the one beside the 5V pin. Would this be a bad idea, or do I have to use the other ground pins? Why would the Arduino board have more than 1 ground pins anyway?

If you have any analog sensors connected to your Arduino, then you should always use one of the Arduino ground pins to connect the ground side of the analog sensor(s), and different ground pins to connect the ground side of any output devices and (if applicable) power. Otherwise, the resistance and inductance of the common ground connection will cause the output and/or power supply currents to induce interference on the analog inputs, giving you less accurate readings.

xEnOnn:
So I can link both digital and analogue components into one single ground pin without issues, right? But if this is the case, when would I need more than one ground pin if I could just link everything all back to one ground pin?

No, in practice this is an issue that crops up on these forums regularly. Whenever you have
a sensitive analog signal to read you need to keep its ground line completely separate from
any ground wire that is carrying a current (such as power source, motors, LEDs, display).

Basically you use a star-ground configuration to prevent IR losses being imposed directly
onto analog inputs. Use separate ground pins for analog sensors and everything else,
to avoid sharing a ground between high current circuits and sensitive analog circuits.

The main reason isn't the wires in fact, its the contact resistance in the socket headers
which can be as high as 100's of milliohms, and change with movement and corrosion,
Most short wire runs are less resistance than this, but can also cause erroneous readings
with larger currents (motors relays and servos especially).

However if you don't have sensitive analog signals, its not usually a problem, the error
voltages are of the order of millivolts to tens of millivolts in most cases.

MarkT:

xEnOnn:
So I can link both digital and analogue components into one single ground pin without issues, right? But if this is the case, when would I need more than one ground pin if I could just link everything all back to one ground pin?

No, in practice this is an issue that crops up on these forums regularly. Whenever you have
a sensitive analog signal to read you need to keep its ground line completely separate from
any ground wire that is carrying a current (such as power source, motors, LEDs, display).

I don't think the Arduino PCB provides much separation of signals.

It might be worth connecting the analog grounds to the pin next to AREF and all the other grounds to the 'power' section. I'd like to see some real measurements before I'll believe it makes much difference though.

OTOH I'm always willing to be proved wrong. Anybody...?

fungus:
I don’t think the Arduino PCB provides much separation of signals.

It doesn’t appear to. However, I can tell you from experience that using a common ground pin + wire + breadboard row to connect both an analog sensor and an output device resulted the analog reading to vary by several lsb when the output was switching on/off. Using two separate ground pins resolved the problem. And in this case, the output device was just a 20mA LED.

dc42:

fungus:
I don't think the Arduino PCB provides much separation of signals.

It doesn't appear to. However, I can tell you from experience that using a common ground pin + wire + breadboard row to connect both an analog sensor and an output device resulted the analog reading to vary by several lsb

That could be the breadboard...