My Sensor node "motherboard" (MySensorsNode)

[Anticimex]

Thanks guys! Well, if AliExpress can deliver this versatility of components, I might consider replacing one of my four sources with them. I have been sceptical of them due to the amount of counterfeits in their stocks, but if you all have good experience with them, that counts for a lot!
I will let you know in this thread when I have finished my sourcing and publish my BOMs. I might do several with different vendors. Unfortunately I have not found a single supplier capable of sourcing everything (and I still don't count the larger modules in that).

[Anticimex]

@scalz thanks mate :) I might be able to part with a board as well once I get them. On DirtyPCBs I plan to put them up on their "store" as well. It won't earn me money but I get some discount on future orders. And if anyone here were interested they could order them there (I'll provide links).

[TD22057]

@Anticimex Very cool project. As someone just starting to learn some basic PCB design, your boards are far above anything I could come up with. I was looking at the board files and noticed that you have a grid of via's underneath the RFM radio. What's the idea behind that may via's? I was under the impression that via's should be avoided and contributed to a lot of RF noise on a board - of course I'm assuming that my understanding is probably wrong, but I'm curious as to the reasoning...

[Anticimex]

@TD22057 thank you! The vias under the radio is in the ground planes. The idea is to make sure the ground planes are evenly grounded. Otherwise they might in some areas act as a capacitor and under the rf parts I want the ground to be as solid as possible. For signals on the other hand, I agree that vias could contribute to notice bit as far as I know this should not be the case for a ground plane. But if you have some link to where vias are discussed I would be interested to see it :) I am not a professional either on this, but I could pass it by my dad. He did this kind of thunk his entire career. So he would give a definite answer :)
EDIT: just talked with him and he agreed that he never experienced noise problem due to via-stiched planes, and that he used that practice as well. So I believe the noise issue you refer to is for signal routes in which case I would agree that vias should be avoided if possible. Unless it would mean ridiculous signal paths of course which is even worse.

[Anticimex]

@bjornhallberg A reflow oven sounds like a nifty thing to have on the bench. I wish I had the time to spare to fiddle with that :) With stencils you could then make some really compact boards.

[Anticimex]

EDIT: All layouts are done. Boring BOM/sourcing work still left to do...

[Anticimex]

EDIT: I went the extra mile and managed to shoehorn in an additional footprint to please @bjornhallberg:s "selfish reasons" ;) so now there is an option to solder a SC-60 based regulator (TPS61221) instead of the SOT-23 based TPS61097A. The first post is updated with the details.

[bjornhallberg]

@Anticimex Woohoooo!

[Anticimex]

@bjornhallberg I actually had a few TPS61221 but I ordered the wrong part (variable output version) so I could never use them. That was for 1.0 where it would serve as 5V reg but since then I ditched the idea of supporting 5V since I encourage everyone to moving away from that. Should be no reason to use 5V for our stuff nowdays.

[Anticimex]

EDIT: BOMs are now uploaded as well. I have to inspect the gerbers one more time but it is close to manufacture now :)

[scalz]

@Anticimex: thx. you have made a great work on this, lot of research I imagine :)
I will look at it carefully, maybe there are interesting ref :wink:
:+1:

[Anticimex]

Thanks,
well at least there are a lot of sourcing alternatives now :)

[scalz]

sure!
just a little question, how do you plan to add daughter board on your smallest board? on bottom?

[Anticimex]

No, on top with some form of riser-board so it goes above the Arduino. If I ever bother. My sensors are socketed so I could just plug them directly onto the connector for that board variant or use extension wires for them.

[scalz]

oki, cool :smile:

[Anticimex]

The small 5x5 board I did most like a favor to anyone who would like to buy a few cheap ones (they are dirt cheap on DirtyPCBs, I will put a order-link to it when I have sent them for manufacture). I will use the board-specific layouts for my "real" sensors since they are tuned to the enclosures I plan to use. Hopefully I got my measurements right...but the 5x5 board will serve as my second prototype run before I tape out the "real" ones. Just so I can verify the design once more before I start deploying my actual sensor network. Took a few years but now I have all my personal "must haves" in place (security and features) so I am ready :D
The boards also have the external flash so I can handle any OTA bootloader variant and it supports both radios in through-hole variants so I can put sockets to easily swap radios later on as well. And I already ordered the 2mm pitch sockets for the RF69 so that is already done.

[scalz]

I totally agree with your vision. your board, you know it, is great, a swiss army knife, useful :smiley:
and I am rather like you, meaning I hope I will start soon my "real" network too. can't wait! but like you said it takes so long time to study, dev and tests...
but it is so fun when it works :)

[Anticimex]

The ultimate satisfaction is to tinker with it, test, improve, optimize, and then deploy and nail it from the start :)

[scalz]

yeah :smiley:

do you plan in future to invest in 3d printer? I am looking at this actually, too much tempting...

[Anticimex]

I was considering it for a while, but realised that I don't have the time for that unfortunately :(
And I am a total novice in 3D design, so I would also need to invest a lot in learning that as well. So I boldly decided to go for off-the-shelf products, or leech other peoples designes through 3dhubs :)