Simple Board Layout - (feather to 3x DS18B20) : multi layer or not?


I am playing around with EasyEDA, and I have a simple project to test it out with - an adapter board that takes a Feather board and attaches 3x DS18B20 sensors. So, super, simple!

Even though the minimum layers is 2 with EasyEDA, I figured that there was really no need to do a double sided layout for such a simple board

in a more complex design, I wouldn’t think twice about using a via and routing on the bottom layer, but for some reason in simple designs it feels wrong!

this is what my initial routing thought was

I’m thinking I can just use the bottom layer as a ground plane and since the headers are through hole I don’t even need vias, i can just route ground on the bottom layer (I can even easily do polygon fills for Vcc and Grnd) - it just feels like cheating!

Would anyone do it differently?

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It may be that you are just starting out, in which case, I’d suggest you go to KiCad. The longer you use the simple tools, the harder it will be to let go when you realize you need something more capable.

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cheers @iabarry - yeah, I have KiCad installed here as well (was just reading the release notes for 7, looks like some good features) - I do like the simplicity of sharing with EasyEDA and the integration with LCSC is nice - saves me hunting for components. But yes, I agree - I wish Altium did something that was more accessible to the home-hobbyist.

However, having said that - I guess my question is still relevant; when you have such simple boards with so much space, there are many more ways to solve a problem… in more complex, tight layouts many decisions can be taken out of your hands (to a degree)… would you do this as a single layer, with longer traces or make use of the second layer and make it simpler and neater? Is there a better component placement you can see?

For a simple board, you have plenty of options. If you don’t need any additional components, a good idea is to minimize trace length for signals. In this case, I might opt to place the row of terminal blocks on the right side of the board.

Something else I would be tempted to do is place a connector and bypass capacitors for Vdd and GND, along with some headers in parallel with the ones you have for plugging invthe ESP module. I often find that when I make boards like these I want to utilize other I/O pins.

Nonetheless, what you have is probably fine. The design has plenty of room for you to add more functionality if (when) you want to add to it.

As for which tool to use, either EasyEDA or KiCad are fine. Altium’s free tool is adequate, but I prefer the other two.

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With simple adapter boards like this, doing it double-sided with ground and power pours allows you to ensure good signal behavior. Looking at the 1-Wire interface for the sensors though, it doesn’t look like there is anything particularly challenging about the signaling, so you could certainly get away with a 1-layer board if you wanted to. But unless you’re making thousands of them and want to keep the cost absolutely rock bottom, or you’re fabbing the board yourself and doing a second layer is a pain, the incremental cost of doing a two layer board is minimal, and also gets you plated through-holes for all those connectors anyway.

Using the online quote tool at JLCPCB, the difference in price between a large order (2000 pieces) of 2 layers vs. 1 layer FR4 boards of similar size (arbitrarily chosen as 100 mm x 100 mm) is only about 11%…


I’ve not used EasyEDA before but if there is an option to, I’d recommend doing some polygon pours and ground + VCC planes. Hit me up if you need clarification.

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short trace lengths was what I had in mind when thinking to use the double layer; sticking to a single layer makes things unnecessary long for sure; the terminals on the bottom was due to where the cables are coming in, though when I think about it (rubber duckying and talking to other people is such a good process!) given the DS18B20 are on cables, and I have so much space, i can put the terminals on the right and run them through the bottom. so good call!

yep, this is actually on my todo list (as well as moving to 0805 since I don’t have space constraints, may as well make it easier on myself). There is a likelihood of a long cable run, so some filtering and Vdd stabilising (decoupling) might be a good thing

are you reading my notebook?! my original sketch had these, i just removed them for simplicity (I am doing this board for a friend and he assures me he doesn’t need them) - i actually also had an alternate header for a Pico; I might do a second version for me (I have a need for a few of these sensor type boards)

yes, in my experience the DS18B20 are very forgiving

cheers mate! I reckon you’ve nailed what the voice in the back of my head was saying…!

thanks mate - polygon pours are absolutely going to happen before I order - the first rev I did had them in place, but then I got to thinking about using the second layer; so this is just the basic routing. Ill make the bottom layer pure ground, and then a VCC polygon fill on the top layer, with cutouts for signalling - ensure a solid, unbroken reference plane

I need to get around to watching Rick Hartley’s “How to Achieve Proper Grounding” ([LIVE] How to Achieve Proper Grounding - Rick Hartley - Expert Live Training (US) - YouTube) webinar (2.20:00!) where I believe he goes through this, I also hear Eric Bogatin’s Signal and Power Integrity Simplified is a great resource… but if you can give me some pointers on how power planes, ground planes, and pours help, that would be appreciated for sure. what I know today

  • reduced sized of current loops
  • reduced trace impedance (which helps reduce noise and improves signal integrity)
  • higher current carrying capability
    also, the reason I chose to make the bottom plane ground was so that it would be unbroken; in this case if i didn’t have the ground plane I can’t imagine I would have an issue, but I am trying to get into good habits.

another reference I have in my notes when I was learning about this is Altium’s Never Cross a Ground Plane Gap in High Speed PCB Design (Never Cross a Ground Plane Gap in High Speed PCB Design | PCB Design Blog | Altium)

Until you are mass manufacturing for a commercial enterprise, difference between 1 and 2 layer is moot. Especially for these quick turnaround prototyping PCB shops, 2 layer and 4 layer is probably majority of their orders. No reason not to do any design using 2 layer and a bottom layer ground pour until you hit some design challenge which requires otherwise.

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