Which Arduino board(s) for this project?

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Hi all, I’ve recently discovered Arduino while searching for a solution to upgrading some of the 30yo tech in my business.

I bought the beginner’s kit and have taught myself the basics. The coding is the easy part as I’ve been using PHP for years, and the electronics/circuitry will challenge me but I’m looking forward to that.

Anyway, I’m after advice on whether I should use one powerful Arduino or multiple cheaper units for this project. I’m looking at controlling 6 individual 240V smart glass panels (40cmx40cm). I’d use a relay to apply the 240V (my sparky will take care of all the high voltage of course) to clear the glass for a short period (and I’ll be varying this period over the course of the week & day). Other outputs include an LED indicator and a pulse to a mechanical counter, and maybe a buzzer.
I’d also like to send data (usage, logging etc) over the web (either to the IoT cloud or my own server). I’m thinking there would need to be local storage also (SD card) to hold the data and then upload it every x minutes.

The input triggers for each of the 6 glass panels will be provided by 6 NAYAX VPOS credit card readers. They’re programmable, but it looks like they pulse out 0.2V, so I assume I’d be looking out for those on analog inputs.

So it looks like technically I could get that all running on any Arduino board that has 6 analog inputs and Wifi, along with an SD card shield, but of course if it fails, then I lose all 6 devices. Also, could a board manage all that at the same time?

Alternatively I could have 6 individual setups all doing their own thing. I’d want them all connected to one mechanical counter though.

Or even having those 6 boards even dumber and talk to a ‘çontrol board’ - another Arduino that takes care of the logging, wifi communication, pulses to the counter? Still all falls over if it fails though.

And I haven’t experimented with wifi yet - Are we able to communicate over wifi while still looping through the main code listening for inputs and controlling outputs?

Any advice or thoughts on this would be greatly appreciated.

Thanks.

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Welcome Karl!

Breaking down your project a bit:

  • 6x digital outputs to control relays
  • 6x inputs from the card readers (0.2 V sounds pretty low - more on this later)
  • A buzzer and LED status outputs
  • Some form of communication and logging

A couple more questions/comments about your setup:

  • 240V devices have to be approved to meet standards, instead of relays I’d look for some off-the-shelf products to switch mains: Remote Controlled Mains Outlet Controller | Core Electronics Australia
  • The 0.2V output seems a bit low, did you use a multimeter or oscilloscope to measure this? Multimeters are slow devices and might not capture the peak, if you have an oscilloscope handy that will reveal the maximum voltage. If its closer to 3.3/5V you can use whats called an interrupt to alert the Arduino or microcontroller to do something later
  • What do you mean by ‘failure’ are there any critical systems attached to this device?

Absolutely, on devices with multiple cores you can use one for handling WiFi and communications and the other for sensor processing (and interrupts to capture real-time events).

If you can clarify from the above a recommendation can be made, though it sounds like you’ll want a kind of ESP32.

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Thanks so much for your reply, Liam
I like the mains switching ideas - I’ll have a look at some options.

I have not measured the pulses yet - I’m just taking that from the manual. However, it does state:
The pulse wires are providing a 0.2V voltage level for up to 200mA current outputs. In case a higher current in required, connect the pulse wire to the VCC or to external power supply.

This is project is in a commercial environment, so any failures result in lost revenue.

Thanks again!

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Hi Karl,

No worries! Since there are significant risks with failure it might be worth hitting up an engineering consultancy to build a robust solution.

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