Arduino Mini 5V

Projects General Guidance
1

Hi guys,
I have a project up and running involving an Arduino Uno, 2 4-digit led displays, 4 shift registers, a couple of switches and a temperature probe. It all works fine on the breadboard with the Arduino Uno.

I want to port it over to stripboard and an Arduino Mini 5v.

With the Uno, I have 1 wire coming from the 5v output pin going to the breadboard where that then feeds into the 4 shift registers, switches and temperature probe.

My problem is that as far as I can see the Mini doesn't have a 5v output pin. What do I do? Do I just run a digital pin high all the time and connect everything to that, or am I missing something stupid?

Any help much appreciated.

2

You are missing explaining what you are using as a power supply, either with the UNO or the (Pro?) Mini.

3

Sorry, it is the pro mini I intend to use. I plan to run it from a 9v battery through the raw input. The Uno is currently running from the usb input from a pc.

As you can tell, I am no more than an enthusiastic beginner.

4

dmkelgin:
My problem is that as far as I can see the Mini doesn't have a 5v output pin.

It's called VCC (next to A3).

The 5volt regulator on the pro mini is tiny, and probably can't supply all the parts you are talking about.
Leo..

5

Ah, I thought that was for powering the board if you had a regulated 5v power supply, I didn't realise it was an output pin.

If it can't power all the components I plan to attach to it, could I use one of the output pins to power some of them? So, in theory, connect the shift registers to vcc, the temperature probe to a digital pin set high constantly and another digital pin high constantly for the switches.

Again, help and advice gratefully received.

6

dmkelgin:
Ah, I thought that was for powering the board if you had a regulated 5v power supply, I didn't realise it was an output pin.

It is the output of the onboard 5volt regulator, and the supply of the MCU.
You could say it's 5volt output as well as 5volt input.

dmkelgin:
If it can't power all the components I plan to attach to it, could I use one of the output pins to power some of them? So, in theory, connect the shift registers to vcc, the temperature probe to a digital pin set high constantly and another digital pin high constantly for the switches.

No.
Power from any pin comes from the MCU's supply, and so from the onboard regulator.

What is the total current of your devices.
The current capability of most 9volt batteries is not that great.
A 5volt micro-power switching supply might be needed to get the most out of the battery.
Leo..

7

Thanks for that.

So my next move is to find out the current supplied by the vcc pin, then add up the current required for all the devices I hope to attach to it. If vcc is greater then I am good to go, if not the 5v micro power switching supply is the way to go.

I think I have this sorted out in my head now :slight_smile:

8

Woohoo, all wired up and working correctly, thanks so much guys :slight_smile:

My wee mini was able to happily cope with running all these components :slight_smile:

9

As far as Arduino projects go,

This is a 9 V battery:

This is not:

10

Your battery stresses the Arduino regulators and wastes power and money - one cell can be removed for ~20% savings.

In many cases 3 cells are sufficient to power 5V boards directly, at nearly 5V, or 2 cells for 3.3V boards.

11

I'm confused, one "square" 9v battery or 6 "round" 1.5v batteries. Why is the square one not 9v as far as the arduino is concerned?

12

Square batteries don't have that much capacity, maybe 400 to 500mAH.
AAA and AA have much more, like 1200mAH and 2500mAH.
3xAA (4.5V to 4.8V) might be all you need and will have longer run time than a square 9V.