Power via 5v for I2C /SPI

I'm starting to think about moving my project from a heap of wires to something more permanent and was wondering about power.

I've looked at https://www.amazon.co.uk/gp/product/B07DYP6L35/ as a source of power, with an output of 2.5A. It seems to be just the thing, and since I want to power a couple of other components too, looks beefy enough. So onto the question.

If I power the Arduino via the 5V & GND pins from the buck converter can I feed I2C and SPI devices power and GND, direct from the buck converter also - bypassing the current limitations on the arduino?

I'm aware when, for example, using an LED strip with an external power supply you connect ground from the Arduino to the ground of the supply powering the LEDs but since I'm powering everything from the same supply do I need to bother? I know it's a "stupid question" but it keeps bugging me and it's all new stuff for me.

If I power the Arduino via the 5V & GND pins from the buck converter can I feed I2C and SPI devices power and GND, direct from the buck converter also - bypassing the current limitations on the arduino?

Yes

I'm aware when, for example, using an LED strip with an external power supply you connect ground from the Arduino to the ground of the supply powering the LEDs but since I'm powering everything from the same supply do I need to bother?

Bother what? All devices will share the same ground, from your description of intended wiring. What else do you think you might need?

LeChatQuiRit:
I'm aware when, for example, using an LED strip with an external power supply you connect ground from the Arduino to the ground of the supply powering the LEDs but since I'm powering everything from the same supply do I need to bother?

How could you not?!? You can't power multiple items with the same power supply and NOT connect them all to the negative/Ground side of the power supply.

johnwasser:
How could you not?!? You can't power multiple items with the same power supply and NOT connect them all to the negative/Ground side of the power supply.

Perhaps I phrased it poorly.

If you're powering the Arduino via USB and you're powering the LED strip from an external supply would be a better description.

ie:

Still vague. How about a complete rephrase of the question, without the ambiguity? I see a diagram. What is the question? In reply #3, you didn't really say anything about the circuit.

Sorry, I tried replying earlier and it complained I was replying too soon.

PaulRB:
Yes
Bother what? All devices will share the same ground, from your description of intended wiring. What else do you think you might need?

Thanks. It's probably because I'm reading a lot about powering arduinos with power fed via USB and an external source.

aarg:
Still vague. How about a complete rephrase of the question, without the ambiguity? I see a diagram. What is the question? In reply #3, you didn't really say anything about the circuit.

Ok, now I've royally confused things :slight_smile:

That diagram is only related to my initial question in response to johnwasser's quoting of me when I talked about the led strip. I wasn't clear that there were 2 sources of power in the original statement. I was trying to clear it up, made it worse.

In this there is only one power source. I was confused and somewhere in the back of my mind I figured I'd read something about potential issues powering as I suggested.

I have a couple of 7 segment displays, an LCD, DS3231 and some neopixel style leds wired up and I want to use an external power source to drive those, and the arduino. At the moment they are powered by the arduino. Adding a 3rd 7 segment display caused the arduino to reset, I suspect tipping it over the edge in terms of current draw. I have other components to add at a later stage (when they get delieverd) but I can progress with development in the meantime. So to clarify: Can I unplug VCC and GND from each component, and connect them to VCC and GND on the Buck converter, and also plug the arduino into the converter via the 5V & GND pins on the arduino.

I appreciate there may be concerns over dual power USB/Buck converter but the intention is to only ever have the arduino powered by one or the other.

LeChatQuiRit:
Perhaps I phrased it poorly.

If you're powering the Arduino via USB and you're powering the LED strip from an external supply would be a better description.

How is that "powering everything from the same supply"? I'm confused.
The Arduino and anything connected to an Arduino pin have to have the same Ground reference. You have to connect the grounds together. If they both are connected to the same power source, they naturally have their grounds tied together at the negative terminal of the power supply.

johnwasser:
How is that “powering everything from the same supply”? I’m confused.
The Arduino and anything connected to an Arduino pin have to have the same Ground reference. You have to connect the grounds together. If they both are connected to the same power source, they naturally have their grounds tied together at the negative terminal of the power supply.

LeChatQuiRit:
…when I talked about the led strip.I wasn’t clear that there were 2 sources of power in the original statement.

Ignore it, it’s not important.