2 Arduino Uno or 1 Arduino Due

Hi! I am working on a project which will include multiple sensors, magnetic valves, LEDs, buttons, etc.
Until now an Arduino Uno board was sufficient but I am starting to run out of pins.
Could I somehow connect another Arduino Uno board or should I look into a larger board like Due or Mega?
Also, a bump up in speed would be nice and I have the impression that creating a connection between 2 Uno boards would not help.

Thank you in advance! :grinning:

2 arduinos are usually double the pain and the bugs :slight_smile:

I would get one that is more capable, or use port extension boards if compatible with what you want to do


Hi, @morarumaria
Can you tell us the application and what sensors you have.
There are I/O expander IC and depending on how other sensors communicate there may be easy ways to make your project easier.

Thanks.. Tom.... :smiley: :+1: :coffee: :australia:

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If your happy with a 3.3V system, I would use an ESP32 based board,
supplemented with I2C/SPI/I2S peripherals as needed.
It has a lot of power (two processors on 240MHz), above 300 kB RAM and a lot of Flash space,
allowing OTA, it has WiFi and Bluetooth, runs a real time operating system and
you can get versions with additional 4 MB RAM.

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Thank you! I will look into port extension boards

I am trying to perform the bubble point test for filter testing using Arduino. I will attach a rudimentary diagram, but I must not that it will also include a control panel and a touch sensor.


About how the sensors communicate, I think I will use Analog pins for all of them. But I am not sure if this was your question. I am newbie and I am still learning :grin:.

@Whandall I just looked into ESP32 boards and it seems like a great choice for my project. Could I use an external power supply for most of my peripherals to make up for the 3.3V limitation?

Most peripheral are available for 3.3V, and you could interface to 5V logic easily if necessary.

All the peripherals should be powered from external power in most of the cases anyway.

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depend on the need, you might only need one uno with a IO port expander like this one
There is a tremendous amount of things available over SPI, if you look closer. I/O port expander, Analog to Digital converter, Digital to Analog converter.
And you only need one pin per chip (MOSI and MISO and SCK are shared)

If you want large number of inputs (such as my 24-button diy joystick), you can use a shift register like the 74HC589.


It is best practice to have your peripherals running on a separate supply to the controller.
That way the controller has a clean glitch free power source.

If your peripherals are 5V and the controller is 3V3, you may need to use a "level shift" board to interface the two.

Tom... :smiley: :+1: :coffee: :australia:
PS. So you have your bubble sensor circuit working OK?

Yes, it is running smoothly. Thank you so much for the advice, @TomGeorge ! :blush: :hugs:

I think I will end up using a ESP32 board with a port expander. Thank you!