[SOLVED] Possible to send data from Arduino Pro Mini 3.3V to Photon?

Mod edit (@harrisonhjones): Solution:
1. Use the search feature. If you can’t find anything make your search more generic.
2. Try to match the IO voltage between two devices you want communicate.

After some effort, I finally have an Arduino Pro Mini (3.3V) that monitors the temp of my outside grill, the ambient temperatures outside and inside, and detects if my deck door is open/closed. I output this to a small OLED that will be mounted in my kitchen to basically keep an eye on the grill and, separately, to tell us if we can leave the deck door open to allow for fresh air without cooling the house. I’d like to push the four outputs (grill temp, outside temp, inside temp, and door status) to a Photon so I can use that data in other applications.

I’ve read where folks have successfully pushed data from a Redboard to a Photon but I can’t get it to work on my Pro Mini. I’m either not following along properly (not surprising since I’m still new to this stuff) or maybe it won’t work without a lot of magic. At a minimum I’d like to get the outside/inside temps to a Photon. I can easily & cheaply do that by just running separate TMPs with my Photon and not worry about the two devices communicating with one another.

So my question: Is it possible without a lot of magic/$ to send data from my Arduino Pro Mini (3.3V) to my Photon?

There are quite a few topics regarding this if you search for it on the forums. Serial communications seems to be popular.
Depending on what it is you’re trying to do, you could replace the entire pro mini by a photon though. It should be more than capable to do what the mini is doing and more.

Thanks, @Moors7. All the threads I found relating to the 3.3V Pro Mini never resulted in a solution, unless I missed one or I misunderstood what I was reading. Both possible.

I’ll have to look back to see why Sparkfun told me to use the 3.3V Pro Mini with the thermocouple. I was originally going to use a RedBoard but they told me that wouldn’t work. It would be nice to use a Photon for the project and eliminate the Pro Mini. I’ll have to dig in a little deeper and see if I can do it without frying anything.

I’m not sure I can use the Photon directly without additional work. The thermocouple breakout requires 3.3V (https://www.sparkfun.com/products/13266). I think I need to educate myself on level shifting as that seems to be the path I need to follow if I hope to use the Photon. My problem is I don’t know what I don’t know, haha.

The Photon runs on 3.3v. Why do you think you need level shifting?

Considering the pro mini is ‘just’ another Arduino, you can abstract the search by looking for communication between an Arduino and Particle. It doesn’t have to be Pro Mini specific since it’ll be the same for (almost) all of them.

You can most definitely use a thermocouple with the photon. Like @harrisonhjones mentioned, it runs on 3.3V as well, so it should be easy to swap. If you look around the forums a bit, you’ll find that there are BBQ projects already that measure temperature, and can even control it.

Ugh. I now see I had a complete lack of understanding on system voltage vs. I/O voltage. This is obviously something basic but of major importance. I just didn’t “get it.”

This project will work MUCH better using a Photon.

Thanks for your help @Moors7 and @harrisonhjones. I’ll be running along now (tail between legs…)

Feel free to delete this post @harrisonhjones.

No worries. I’m sorry if we made you feel scared, nervous, ashamed, etc (ref “tail between legs” comments). That was not my intention. If you’d like to delete this post PM me but I’d prefer to leave it up. It illustrates two things:

  1. The search feature on the forums works and it’s useful to start specific and work your way to more broad search terms if you can’t find what you were looking for.
  2. System voltage and I/O voltage are sometimes different voltages but I commend you for checking and not just plugging it in and hoping for the best.
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Nah. Leave it up. I’m learning. I just had a stumbling block that I didn’t recognize as so basic. This stuff is well outside my realm and I’m sure I’ll come across more of the same.

Regarding the search feature. Yes, that is incredibly helpful IF you understand what you’re looking for. I’ll get there.

Lastly, I find this group extremely professional and helpful to people of all levels. I would be stuck without it.

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