Just a warning upfront - I'm an engineer, but not an RF engineer, so I do see some things, but I'm almost guaranteed to miss others.

As far as your highlighted line, it is a trace, but not a via. A via connects the trace on one plane of copper with a trace on another plane.

That trace should really be as short and direct as possible. Wrapping around the back of the module and along other signal lines is not a good idea. I see that the closest line to it is 3.3V power, so that acts basically as ground for small signal, but any power spike is bound to couple into the antenna line as well, at least some. If possible, it would be best to have ground on both sides of the antenna trace on that side of the board, as well as the whole surface on the other side of the board from it. Might also want to guard it by having vias connect the ground planes on either side of it to make kind of a 3d cage around it.

Additionally, you should try for 50 ohm trace impedance on the antenna line. However, there is no one-size-fits-all answer for the width of this line. It depends on the exact board parameters, and even to a small amount on the frequency of the signal. There are trace width impedance calculators that you can use to get this answer. https://resources.pcb.cadence.com/blog/2019-just-how-wide-should-a-pcb-50-ohm-trace-width-be

Almost guaranteed that it's correct to ground those 4 outer pins of the antenna connector. View the datasheet of the specific connector you are using to be 100% sure.

@NeverDie said in Which vector network analyzer should we buy?:

It said version 2 was due in January.

It looks to me like it's available now. After where it mentions the 2.0, there's a link where it says 'authorized dealer.'

That link goes here: https://www.tindie.com/products/hcxqsgroup/nanovna-v2/

And it says you can buy it now for a little under $60 US.

I don't know anything else about it, but I'm also considering getting one, now that I've read about it in this thread. I like the idea.

I think your numbers look good. Nice job getting the trace much shorter - that should help a bunch.

I wouldn't even bother with an Arduino/microcontroller at all for this. Just some diodes on each circuit and maybe some transistors for powering the large LED strips, or could also use tiny relays.

But I don't see where it has anything nearly complicated enough to have code running on a chip to run anything on it. @itjobhunter if this is not helpful and you need more specific details and/or a quick napkin sketch I can throw something together to show what I'm trying to say.

At least here where I am - West coast of US - they're allowed +/- 10% and still be counted as within spec. So those numbers are fine.

The thing is, they have voltage transformers with multiple contacts inside, and they will step the voltage up or down on the neighborhood feeders as necessary to account for varying voltages on the higher voltage lines. Actually, I think the switching happens going from high to medium voltage, and there aren't really that many of the switching transformers in the system. All of your local transformers for the houses wouldn't have them - that would be far too spendy. They do it on a large scale.

But as the residential power demands change over the day, they use the switchers to keep everything balanced. They could keep the voltage variance smaller, but at the cost of more frequent switching, and every switch of the contacts creates some wear, so more maintenance eventually. Every switch also creates some ripples in the rest of the system, I'm pretty sure. But those are probably pretty minor - it's a very stiff system. Also having higher resolution on the switchers would be more complicated and have more parts/windings inside every one of them. They keep the frequency very tightly regulated, but allow the voltage to float a bit. The frequency variances they have to make up for throughout the day so that over the course of a whole day there's practically no net change at all. (For the sake of clocks that literally count cycles and therefore don't need a crystal.)

Actually, allowing the voltage to vary also has another nice benefit to the system - it allows for a natural damping of disturbances. When the voltage dips a bit because of increased demand, the power used by many resistive appliances will also dip, so that can help the system in recovering as potentially more generation is brought online. I don't think something like AC that has a spinning motor helps much, as the frequency won't vary much.

Sorry if you're aware of most of this. I worked for the power company for a while, though that has been some years ago now.

I know this an old topic now, and I don't know if this would still help you @otousset, but I ended up running across this while searching for a solution, as I had the same problem. I finally found the solution at this page: https://docs.platformio.org/en/latest/platforms/ststm32.html

What it comes down to is that there are two different 'Arduino' cores with platformio, and we have to use the 'maple' one, which has the libraries in the format that the MySensors expects to see. The line:
board_build.core = maple
has to be added to the platformio.ini file in the project folder, which switches the core to be what MySensors framework needs. Then I got it to compile without complaint. (Well, but I guess I haven't actually finished my installation to be sure that it works with the gateway...)

Yes, lower frequencies are better for going longer distances and penetrating walls, etc. I also would not try the NRF radios. 2.4GHz almost certainly won't do it.

The 433MHz RFM69 might do it, but I would be a bit surprised. I think your best shot is to try a LoRa module, so the RFM95 might do it.

If it doesn't work right away with just the boards and basic antennas, it's always possible to get better range with a good setup of directional antennas. In fact, sometimes having the right antenna is almost more important than the radio. (Not really, but it is super important.)

Sorry about all the replies, but I just remembered one more thing. I was using the current version of MySensors, but I also then switched to the development branch, just to see if it changed anything, but that also didn't do any good. (Didn't do any harm, either.)

Well, it could be that the issue is the voltage regulator on the Arduino board. The higher the input voltage, the more power/heat that needs to be burnt at the voltage regulator. Maybe it's self-limiting because it's getting too hot?

The Arduino website lists this part as the voltage regulator:
https://www.mouser.com/datasheet/2/146/SPX1117-1889129.pdf

On page 6 it claims a thermal resistance to ambient of 46 degrees/W. If you're using 1A and have 12V input then you're dropping 7W across the regulator. This is a temp rise at the junction of 322 degrees over ambient, which it obviously won't do. The datasheet also says that it's internally regulated and will current limit at 155C. Assuming 25C ambient, this only leaves a margin of ~2.8W that can be dropped over the regulator. So you'd have problems with any more than around 400mA. To have a safety margin, I wouldn't plan on more than 300mA or so, or maybe even down more towards 200.

This voltage regulator is a nice, low dropout one, so if you could power it from a supply that gave it 6 or 7V instead of the 12 that would give you a ton more thermal margin and the regulator could then allow a lot more current through.

Well, I guess I'm just talking to myself. I must be the only one running into this right now.

I did manage to fix it, but it's a bit of an ugly way to do it. I've compared the code for different frameworks in platformio, and I haven't really figured out why it fails on STM32, but not the others I've tried. No, I haven't exhaustively tried them all.

In the .platforio/packages/framework-arduinoststm32-maple/STM32F1/cores/maple/main.cpp file it's really almost completely empty. But then, so is the one from MySensors, though it has one addition for serialEventRun. Interestingly, other frameworks through platformio have this line as well, just not this one.

Anyway, the MySensors one has that extra, so I commented out the maple one through platforio, and then it lets the compilation complete. I haven't gotten far enough to know for sure that it doesn't cause further problems down the line, but I hope this is progress, and I wanted to get it written down while it's still fresh in my mind.

Well, it could be that the issue is the voltage regulator on the Arduino board. The higher the input voltage, the more power/heat that needs to be burnt at the voltage regulator. Maybe it's self-limiting because it's getting too hot?

The Arduino website lists this part as the voltage regulator:
https://www.mouser.com/datasheet/2/146/SPX1117-1889129.pdf

On page 6 it claims a thermal resistance to ambient of 46 degrees/W. If you're using 1A and have 12V input then you're dropping 7W across the regulator. This is a temp rise at the junction of 322 degrees over ambient, which it obviously won't do. The datasheet also says that it's internally regulated and will current limit at 155C. Assuming 25C ambient, this only leaves a margin of ~2.8W that can be dropped over the regulator. So you'd have problems with any more than around 400mA. To have a safety margin, I wouldn't plan on more than 300mA or so, or maybe even down more towards 200.

This voltage regulator is a nice, low dropout one, so if you could power it from a supply that gave it 6 or 7V instead of the 12 that would give you a ton more thermal margin and the regulator could then allow a lot more current through.

mfalkvidd gave you a great link, but if you ever need to see any possible choices, you can run

./configure --help

and it will show you. The extra flags section is one thing (of many) that it says.

Actually, this is very timely for me, as I'm trying to troubleshoot my own radio issues, so I'll use those extra two flags that you mentioned and see what they say.

Thank you!

Oh, and Skywatch's tips are also good. Solid power is very important. I would put a few different capacitors as close to the power pin of the radio module as possible. 100n, and then a selection from: 1u, 4.7u, and 10u. I would likely go with 2 of those microfarad capacitors, and maybe all three. I like to err on the side of overkill where power capacitors are involved.

I think your numbers look good. Nice job getting the trace much shorter - that should help a bunch.

Just a warning upfront - I'm an engineer, but not an RF engineer, so I do see some things, but I'm almost guaranteed to miss others.

As far as your highlighted line, it is a trace, but not a via. A via connects the trace on one plane of copper with a trace on another plane.

That trace should really be as short and direct as possible. Wrapping around the back of the module and along other signal lines is not a good idea. I see that the closest line to it is 3.3V power, so that acts basically as ground for small signal, but any power spike is bound to couple into the antenna line as well, at least some. If possible, it would be best to have ground on both sides of the antenna trace on that side of the board, as well as the whole surface on the other side of the board from it. Might also want to guard it by having vias connect the ground planes on either side of it to make kind of a 3d cage around it.

Additionally, you should try for 50 ohm trace impedance on the antenna line. However, there is no one-size-fits-all answer for the width of this line. It depends on the exact board parameters, and even to a small amount on the frequency of the signal. There are trace width impedance calculators that you can use to get this answer. https://resources.pcb.cadence.com/blog/2019-just-how-wide-should-a-pcb-50-ohm-trace-width-be

Almost guaranteed that it's correct to ground those 4 outer pins of the antenna connector. View the datasheet of the specific connector you are using to be 100% sure.

@mutantx Is there something lacking from the circuit diagram on the openhardware page? I'm not the original creator, but it seems like everything is on there.
https://www.openhardware.io/uploads/58f4f976bacb0bcc79a15e93/394/DFPlayer_NRF_ProMini2_4.5V_Steckplatine.png

But back on topic - that device looks pretty cool, if it does half of what it claims. I'm a little tempted, even at my own cost. I won't, but if my insurance company ever offers it, I'll jump at it.

Yes, it's a little 1984. But I also already signed up for an app with my car insurance that monitors my driving. It doesn't have any hardware, just GPS and accelerometer from my phone, but it doesn't cost me anything other than some power and I guess privacy. But it saves me something like 15% and I don't have to do anything. I guess if I ever really care about it watching me go somewhere I can disable it for that amount of time.

A little weird what we're willing to put up with, I guess. Though I also like the fact that with a record of how I drive, if there's ever an accident, it might also be possible to subpoena the data in my defense if really necessary. Or maybe that's just what I tell myself to help justify it?

At least here where I am - West coast of US - they're allowed +/- 10% and still be counted as within spec. So those numbers are fine.

The thing is, they have voltage transformers with multiple contacts inside, and they will step the voltage up or down on the neighborhood feeders as necessary to account for varying voltages on the higher voltage lines. Actually, I think the switching happens going from high to medium voltage, and there aren't really that many of the switching transformers in the system. All of your local transformers for the houses wouldn't have them - that would be far too spendy. They do it on a large scale.

But as the residential power demands change over the day, they use the switchers to keep everything balanced. They could keep the voltage variance smaller, but at the cost of more frequent switching, and every switch of the contacts creates some wear, so more maintenance eventually. Every switch also creates some ripples in the rest of the system, I'm pretty sure. But those are probably pretty minor - it's a very stiff system. Also having higher resolution on the switchers would be more complicated and have more parts/windings inside every one of them. They keep the frequency very tightly regulated, but allow the voltage to float a bit. The frequency variances they have to make up for throughout the day so that over the course of a whole day there's practically no net change at all. (For the sake of clocks that literally count cycles and therefore don't need a crystal.)

Actually, allowing the voltage to vary also has another nice benefit to the system - it allows for a natural damping of disturbances. When the voltage dips a bit because of increased demand, the power used by many resistive appliances will also dip, so that can help the system in recovering as potentially more generation is brought online. I don't think something like AC that has a spinning motor helps much, as the frequency won't vary much.

Sorry if you're aware of most of this. I worked for the power company for a while, though that has been some years ago now.

I wouldn't even bother with an Arduino/microcontroller at all for this. Just some diodes on each circuit and maybe some transistors for powering the large LED strips, or could also use tiny relays.

But I don't see where it has anything nearly complicated enough to have code running on a chip to run anything on it. @itjobhunter if this is not helpful and you need more specific details and/or a quick napkin sketch I can throw something together to show what I'm trying to say.

Well, I don't know what all is in the video, because I'm not going to watch a 27 minute video about it.

However, those modules often fail due to bad power supply. Adding some capacitance to the power rail is supposed to take care of it. I've read about it multiple times, but I haven't used them hardly at all myself.