Advice please: First electronics project - IoT air quality and temperature sensor

Hi all, first post here, so be gentle. :slight_smile:

I am looking to make an IoT air quality and temperature sensor that uses MQTT to send values back to my established Home Assistant server.

My relevant skill levels:

  • I’m a pretty decent programmer in a range of different languages. I’ve not used Micro Python yet, but it doesn’t look too scary.
  • I’ve got near zero electronics skills. The last thing I made was a Dick Smith Electronics wireless microphone kit. That was about 30 years ago.

I watched a bunch of guide videos on Youtube including the fantastic guide videos and eventually found the PiicoDev module videos from Core Electronics (nice work on the guide videos!).

I’m currently planning to use the PiicoDev range paired with a raspberry Pi Pico W. Seems like the perfect fit for me - capitalising on my existing skills, and keeping the electronics simple (eg: plug A goes in slot A).

The key gear I am looking at:

The advice I’m after is…
If I am looking to gain a little actual electronics skills/knowledge from this project, what would be a variation on the above plan (or completely different plan) that would introduce a little bit more electronics-DIY in to the job?

Thanks in advance for any insight you might have.

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Hi Gerard

It would appear that you might favour a no tools approach, ie; just plugs and sockets without mundane things like soldering irons, hand tools and the like. If this is the case most of your input will be program related.

I don’t really know where you would want to start with “actual electronics skills/knowledge” or exactly what you mean. You might want to re-visit and establish where you left off even if it was 30 years ago. In my humble opinion starting half way up the tree has never and never will work. It usually ends with lots of confusion, frustration and general hair pulling and head spinning. Sit down and think carefully about what you want to do and then how best to go about doing it. You can’t learn it all in 5 minutes.
Cheers Bob

Hi @Robert93820,
Thanks for your response and your time.

It would appear that you might favour a no tools approach

Less my favored approach, and more the only one I know how to make sense of with my current skills.

If this is the case most of your input will be program related.

Yes, that was my understanding too. That’s why I was asking if there was a way to introduce some basic electronics work in to this project. As for what I mean? That’s a good question, and I don’t really know. Soldering, bread-boarding, using raw components instead of pre-made modules? That was where I was hoping the advice would come - to help educate me of the possibilities.

You might want to re-visit and establish where you left off even if it was 30 years ago. In my humble opinion starting half way up the tree has never and never will work.

That may be sound advice. I was trying to figure out if there was a way of carving out a little introductory electronics project inside this project - eg: instead of using the RGB LED PiicoDev module, using some RGB LEDs and any other required components and interfacing with them directly.

…but I don’t know what I don’t know. Perhaps this is already too far “up the tree”?

If this is the general consensus, I might look at keeping this project plug-and-program so-to-speak, and do a separate more introductory electronics project.

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Hi Gerard
Looks like you have your head in the right place.

That seems to be the right order of things. I would start with Soldering and tools which will only come with practise. There are lots of tutorials on this, some good and some bad. I came across a good video some time ago, should have book marked it but if I get enough time I will see if I can find it. It was one of the better ones re soldering. There is a lot of info out there you will just have to try to filter out the useless stuff.
Next to get to component level you need to be familiar with Volts, Current (amps and submultiples of), Power (Watts and multiples/submultiples of), Resistance (ohms) and to a lesser extent reactance. Resistance is sometimes called impedance which can be resistive (the same as resistance) or complex (the combination of resistance and reactance) but don’t concern yourself with this one at this stage, just be aware that it might come up.
That is a start and having got your head around this a lot of what follows will just fall into place and be easier to understand. If not this subject can be totally confusing.
This will also help immensely when knowing what questions to ask and interpreting and evaluating what you are advised. There are a lot of queries that start out very vague and incomplete and sometimes it is like pulling teeth getting enough information to even think about a problem. basically if you have this basic knowledge it will help everyone.
Keep going
Cheers Bob

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Hi Gerard,

Your plan to design a project around your current strengths and then learn by expanding upon it sounds sensible to me. While PiicoDev can be used with no tools or soldering the option is built-in to add headers and mount your modules to another circuit board.

Personally, I think soldering is one of the most useful electronics skills someone can learn, and soldering header pins is one of the lowest risk soldering jobs to develop your skills on.

I’d suggest building your project with a no-tools prototype utilising the PiicoDev cables to connect everything. Then once everything is working learn to solder by making a custom protoboard to mount and arrange your modules using male and female headers.

This protoboard might be helpful if you did want to solder it all up to mount.

Soldering random components for the sake of practice is good for your skills but you don’t end up with a useful device for your work, I think this should be well within reach and still be handy once you’ve finished putting it together.

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Add on
A couple of videos to get you going.

I haven’t found the one I was looking for but these are not too bad.
One thing I noticed when soldering through hole components these guys bent the leads over, soldered and then cut the leads. If the components have thicker leads best practise is to cut first then solder. This removes the heat sinking effect of the larger lead and minimises the possibility of a cold joint. When I was working at AWA their Standard Practice Manual decreed that ALL leads to be cut before soldering. This had the added advantage of coating the bare copper wire end with a protective layer of solder.
Cheers Bob

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Hi Gerard.

If you’re not ready for soldering but still want something more hands on, get a Pi or Pico W with headers pre-soldered, a breadboard, and some jumper wires. That way you can connect things like LEDs to your Raspberry Pi without soldering. I’ve got a couple of projects using mini breadboards for this reason.

I hate soldering but some of my recent projects needed it, so I had no choice but to lean!

@Robert93820: Your advice of the various places to start learning was quite helpful - thank you!

@Robert93820: The videos are super helpful, and your suggestion to cut, not bend, sounds sensible. Thanks for taking the time to come back to share all that.

@Trent5487676 and @Robert93820: You both suggested soldering as a good place to start developing my skills. I’m going to go with that.

I love this! I have read up on how to mount the piico dev modules via the breakouts. I also like that this will mean I can reuse the PiicoDev LiPo Expansion Board for Raspberry Pi Pico for future PiicoDev prototyping projects.

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@Steven - thanks for your suggestion. I’m not sure if I’ll hate soldering yet. I like the idea of being able to easily reclaim the parts if I go down a no-solder route, but I also like the robustness of the solder path. Your suggestion got me thinking though…

Perhaps I’ll sub out the LED Piico Dev module, and instead add some individual Glowbit LEDs. I was only intending to use 3 LEDs, but eventually I’ll be placing this IoT device in a housing that I’ll custom build, and I want to put the LEDs into cut out recesses in the housing. From what I can tell, having the LEDs outside of the Piico dev module will make it easier to mount in the custom recesses.

After a bit of reading tonight I’m still not clear on how much I’m biting off by choosing to go down that glowbit-LED-path. Eg: Will I need other components like resistors? From what I can tell, the answer is “no - the glowbit leds are ready to use as is”. Please correct me if I’m wrong.

I think (at a basic level) I need to wire the 3 glowbits together, then connect that unit to the rpi via appropriate breakouts.

Updated plan

  • Slight adjustment to parts list from opening post:
    • RGB PiicoDev module
    • 3 Glowbit LEDs
  • Go the plug-and-program (no solder) route to prototype project.
  • Solder rpiPico, modules and LEDs to ProtoBoard.

Thoughts?
If there aren’t any glaring pitfalls with my current plan that any of you see, I will pull the trigger on this purchase and get going on the project.

Thanks again for everyone’s advice and support!

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I have a GlowBit 4x4. No extra parts, just soldered on some headers, and powered it straight from the raspberry pi’s 5V pin.

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Hi Gerard
I think you are going down the right path. Good soldering is a must and you will only master it by reading the correct material and practise.

I meant to cut after bending and before soldering. The whole text reads that the component lead shall form an angle of 15º with the board. This to facilitate removal. AWA were always mindful of being able to remove components etc after manufacture during any repair. With this in mind if the component will stay in position not bending at all would be better again.

Stephen’s quote. Note the word “soldered”. Says it all. If you are going to dabble in this sort of thing proficiency in this is a must to be successful.

A note on this subject. Some tasks are a bit specialised. Many years ago a colleague of mine went on a “high reliability” soldering course. This entailed 6 weeks in USA but when he returned he was qualified to instruct others. So you see it is quite an important skill and not just about melting a bit of tin/lead alloy.

One of these videos suggests that resin core solder has 1 core. The modern solder (of about 50 or so years to my knowledge) has 5 cores.
Cheers Bob
PS. Get a quality temperature controlled soldering iron before you start. You will save hair pulling and frustration down the track.

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Hi all, Thanks for all the advice. I’m going to pull the trigger on this purchase.

I’ll eventually report back here with my progress, and likely to ask for more advice.

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