Pre-assembled sensor modules
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@alex28 I agree with you about the "stupid" obsession of getting the cheaper stuff with low quality.
@Phil-Whitmarsh you're confounding mini-Pro design (like the OP did) and nano design. RF-Nano is not a low power board
About RF, this is simple actually, like tbowmo said RF certification (CE/FCC for example) depends on a design.
That means module manufacturers certified their module for a very specific setup:- gnd size, shape of the board and layout, placement of the module, enclosure or not, etc
- software used during the certification
So as soon as you change one of these params, you'll lose RF certification because RF characteristics will change. Simple as that. Of course, if new design is compatible, it should be straitghtforward to re-certify the new design.
Development boards (like the OP did) are in a "grey zone", regarding certifications, so for developments purposes.
FCC is more strict than CE. With CE, you can easily certify your board if you're able to provide the documents and proof that your board is RF "green" (no bad harmonics etc) , well tuned, and that the firmware is compliant too.
No idea if the OP tuned his board, or just used parts values from a reference schematic. But to me this looks like a development board with no guarantee for RF perf. -
@alex28 I agree with you about the "stupid" obsession of getting the cheaper stuff with low quality.
@Phil-Whitmarsh you're confounding mini-Pro design (like the OP did) and nano design. RF-Nano is not a low power board
About RF, this is simple actually, like tbowmo said RF certification (CE/FCC for example) depends on a design.
That means module manufacturers certified their module for a very specific setup:- gnd size, shape of the board and layout, placement of the module, enclosure or not, etc
- software used during the certification
So as soon as you change one of these params, you'll lose RF certification because RF characteristics will change. Simple as that. Of course, if new design is compatible, it should be straitghtforward to re-certify the new design.
Development boards (like the OP did) are in a "grey zone", regarding certifications, so for developments purposes.
FCC is more strict than CE. With CE, you can easily certify your board if you're able to provide the documents and proof that your board is RF "green" (no bad harmonics etc) , well tuned, and that the firmware is compliant too.
No idea if the OP tuned his board, or just used parts values from a reference schematic. But to me this looks like a development board with no guarantee for RF perf.@tbowmo @scalz
Hmm, I'm not so sure about the certification requirements. I'm not a lawyer (and it might be best to consult with one in case of doubts if you want to market your own RF product), but as far as I understand the legalese, if you use an RF module with "Full Modular Certification", you are not required to apply for a RF compliance certification anymore. You are highly encouraged to do self-hosted RF testing. And other compliance testing / certification might still apply (mains voltage use, spurious digital emissions etc). This is for the FCC. EU regulations are probably similar / less restrictive.Here's an interesting document from SiLabs. Look at page 15, chapter 3.5.1.1:
"3.5.1.1 How Do Customers use FMA?
• No separate certification with the end product; just label the product and get instant access to the markets.
• The host must be labelled that it includes a certified module.
• An end product using a radio with full modular approval will not need radio certification testing if the restrictions mentioned in themodule grant are met."They do mention that the module must adhere to certain characteristics to qualify, like a fully shielded RF part. So the RFM I linked to above will probably not work.
Here's a document from the FCC outlining the recommended self-testing procedures, filing and product labeling requirements. Note chapter 3.1:
"Testing of the host product with all the transmitters installed is recommended,to verify that the host product meets all the applicable FCC rules. The radio spectrum is to be investigated with all the transmitters in the final host product functioning to determine that no emissions exceed the highest limit permitted for any one individual transmitter as required by Section 2.947(f). A formal application for certification submission containing the results of this investigation is not required. The host manufacturer is responsible to ensure that when their product operates as intended it does not have any emissions present that are out of compliance that were not present when the transmitters were tested individually."
So if you use pre approved modules, you do not need to re-certify. But you're legally responsible to make sure you're within the regulatory limits. You still need to file with them (and pay them) and label your product appropriatlty.
At least that's what I could gather from quickly trying to parse the legalese :grinning:
That said, the general certification processes, registration and filing fees, etc will still cost you a few thousand Dollars / Euros. But that's nothing compared to RF compliance testing when not using a pre-approved module, which can easily go into the 20k-30k range.
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@alex28
I'm not saying we need to certify our homemade devices.
Personnally I don't mind, but just try to make my devices with those constraints in mind.
Certification also depends on firmware, on RF bands etc (CSMA, etc to not spam bands for subghz for example).
Change some characterictics of pcb, gnd size etc, and it can untune center frequency of antenna for sure. Lot of examples in app notes.
Though, from what you read, you can see the "host manufacturer is responsible", and should check by doing tests if it's compliant with his new design. That's what I read.Like I said, I'm pretty sure OP design is not certified, and maybe not even RF tuned.
But as a development board, it's not a very big problem.
And low range nrf24 is less problematic for regulations, than using a subghz module with untuned antenna (change gnd size, and you have to shorten or add length to antenna, else centerfreq is shifted), with a wrong fw spamming the band, unregulated TX power, or also when you add to the design some AC, relays etc which could introduce some noise (bad SNR etc) , like we can see sometimes in diy, + dupont cables which can acts like antennas too. -
Pretty sure Arduino wrote about their hassles getting an Arduino board with a radio out onto the market, even when using a module it was a hassle.
I'm wondering though, wouldn't it be possible to sell a PCB that allows just plugging in every component?
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@alex28
I'm not saying we need to certify our homemade devices.
Personnally I don't mind, but just try to make my devices with those constraints in mind.
Certification also depends on firmware, on RF bands etc (CSMA, etc to not spam bands for subghz for example).
Change some characterictics of pcb, gnd size etc, and it can untune center frequency of antenna for sure. Lot of examples in app notes.
Though, from what you read, you can see the "host manufacturer is responsible", and should check by doing tests if it's compliant with his new design. That's what I read.Like I said, I'm pretty sure OP design is not certified, and maybe not even RF tuned.
But as a development board, it's not a very big problem.
And low range nrf24 is less problematic for regulations, than using a subghz module with untuned antenna (change gnd size, and you have to shorten or add length to antenna, else centerfreq is shifted), with a wrong fw spamming the band, unregulated TX power, or also when you add to the design some AC, relays etc which could introduce some noise (bad SNR etc) , like we can see sometimes in diy, + dupont cables which can acts like antennas too.@scalz I think you misunderstood my post. This is not about homemade devices, it's about commercial ones. And if I read the documents I linked to right, then the things you mentioned (firmware, PCB arrangements, etc) will not affect certification, as long as you strictly adhere to the application notes of the pre-certified module (ie. don't use it in a way that will make its certification break and don't modify it). As long as you follow those, you don't need to re-certify. You are however legally liable in case you mess up or do something you shouldn't (and you're supposed to self check it).
I'm not sure how this relates to development boards. It might depend on what market you sell to. If you're B2B only, then you can probably sell uncertified modules and have your customers certify them. If you sell to the general consumers (and that probably includes DIY tinkerers), then things are not that simple. But that's just my gut feeling.
@Avamander The OPs idea is a simple easy to use quickstart board for beginners. Requiring them to solder SMD components kinda goes against the whole point of it.
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@scalz I think you misunderstood my post. This is not about homemade devices, it's about commercial ones. And if I read the documents I linked to right, then the things you mentioned (firmware, PCB arrangements, etc) will not affect certification, as long as you strictly adhere to the application notes of the pre-certified module (ie. don't use it in a way that will make its certification break and don't modify it). As long as you follow those, you don't need to re-certify. You are however legally liable in case you mess up or do something you shouldn't (and you're supposed to self check it).
I'm not sure how this relates to development boards. It might depend on what market you sell to. If you're B2B only, then you can probably sell uncertified modules and have your customers certify them. If you sell to the general consumers (and that probably includes DIY tinkerers), then things are not that simple. But that's just my gut feeling.
@Avamander The OPs idea is a simple easy to use quickstart board for beginners. Requiring them to solder SMD components kinda goes against the whole point of it.
Requiring them to solder SMD components kinda goes against the whole point of it.
Depends on the component though. Most sensors sold by Adafruit, AliExpress and so on, come on boards that have breadboard-compatible pin-headers. Plugging in those isn't hard compared to placing all those things on a perfboard and wiring all that stuff up.
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@alex28
yes, but when you design a board it's very rare to follow application notes to the letter, because you want a different size of board etc. But I agree about the pre certified module which help a lot for selling hw.I'm just saying there are nuances, it's not a big YES or NO. This depends what components are on the final board, most of the time it may just affect range, or worse introduce noise through power supply, signals lines etc. To check that you can use rf spectrum analyzer, scope..You can have a very good module, but make a crappy design with it. So it all depends on the designer. That's just what I meant. I don't want to debate on this, really.
When I design boards, I don't certify them, I just to try do my best and put constraints on myself regarding the final design I want (filtering if needed, not splitting gnd planes for Rf perf, and lot of others details etc). On other side, I've seen lot of bad designs on different stuff on aliexpress, and not talking about soldering quality. This needs trained eyes.some "funny" stories, for diy-ers
https://hackaday.com/2019/05/15/the-great-ohio-key-fob-mystery-or-honey-i-jammed-the-neighborhood/
https://hackaday.com/2016/08/26/police-baffled-send-for-the-radio-amateurs/so for example, pick a powerful amplified LORA module on 433mhz for example, add an untuned antenna (lot of them on aliexpress), use bad power supply and some others stuff providing parasites, dupont cables, use unregulated max TX power, custom fw with no check before sending (listen for free channel), unlimited number of msg per sec etc and it could be a good example of a crappy device.
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@alex28
yes, but when you design a board it's very rare to follow application notes to the letter, because you want a different size of board etc. But I agree about the pre certified module which help a lot for selling hw.I'm just saying there are nuances, it's not a big YES or NO. This depends what components are on the final board, most of the time it may just affect range, or worse introduce noise through power supply, signals lines etc. To check that you can use rf spectrum analyzer, scope..You can have a very good module, but make a crappy design with it. So it all depends on the designer. That's just what I meant. I don't want to debate on this, really.
When I design boards, I don't certify them, I just to try do my best and put constraints on myself regarding the final design I want (filtering if needed, not splitting gnd planes for Rf perf, and lot of others details etc). On other side, I've seen lot of bad designs on different stuff on aliexpress, and not talking about soldering quality. This needs trained eyes.some "funny" stories, for diy-ers
https://hackaday.com/2019/05/15/the-great-ohio-key-fob-mystery-or-honey-i-jammed-the-neighborhood/
https://hackaday.com/2016/08/26/police-baffled-send-for-the-radio-amateurs/so for example, pick a powerful amplified LORA module on 433mhz for example, add an untuned antenna (lot of them on aliexpress), use bad power supply and some others stuff providing parasites, dupont cables, use unregulated max TX power, custom fw with no check before sending (listen for free channel), unlimited number of msg per sec etc and it could be a good example of a crappy device.
@Avamander But then aren't we back to the old 'get Arduino board with headers, get a random nRF module with headers, plug them together with jumper wires and - nothing works' scenario ? What I really liked about the original idea was that this would be an all in one, no headaches, everything just works module. Where you don't need to worry about fake components, decoupling caps, bad voltage regulators, etc.
@scalz said in Pre-assembled sensor modules:
@alex28
yes, but when you design a board it's very rare to follow application notes to the letter, because you want a different size of board etc. But I agree about the pre certified module which help a lot for selling hw. I'm just saying there are nuances, it's not a big YES or NO. This depends what components are on the final board, most of the time it may just affect range, or worse introduce noise through power supply, signals lines etc. To check that you can use rf spectrum analyzer, scope..Correct. And according to the FCC docs, you're supposed to check for all this on your own. With regulations, it kinda is a black and white YES or NO. Either you're compliant or you're not. When using a pre-certified RF module, it's upon yourself to check for this. If you're in a almost YES but not quite situation and you sell it regardless, well, then you take a legal risk.
But that's the price you have to pay if you want to go commercial I guess. None of this really is a problem for simple DIY stuff you use at home (exceptions apply, see the stories you linked lol).
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plug them together with jumper wires and - nothing works' scenario
No not really, because the jumper wires are exactly the thing a pre-made sensor PCB would avoid.
Where you don't need to worry about fake components, etc.
That depends where the person sources the components to populate the PCB, it's up to the individual to decide if they want to take the risk. What would be a better alternative here?
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@alex28 my limited english meant manufacturers docs are to be taken with a pinch of salt. Of course, I agree, with regulation it's black or white :)
My logic is if manufacturer doc said your device is certified because you're using a pre-certified module, and you broke the precertification in device design, then it's not certified anymore. Simple logical AND, binary black and white.
If you tell me that your device with a precertified module is certified, I would ask you "do you have the certification paper of your device". If no, "do you have the tests results proving what you're saying?". No? So you didn't check it, it's not certified, it's just words :)
of course it depends of the type of design, and like I said I don't mind about these details, it just makes sense to me -
@alex28 my limited english meant manufacturers docs are to be taken with a pinch of salt. Of course, I agree, with regulation it's black or white :)
My logic is if manufacturer doc said your device is certified because you're using a pre-certified module, and you broke the precertification in device design, then it's not certified anymore. Simple logical AND, binary black and white.
If you tell me that your device with a precertified module is certified, I would ask you "do you have the certification paper of your device". If no, "do you have the tests results proving what you're saying?". No? So you didn't check it, it's not certified, it's just words :)
of course it depends of the type of design, and like I said I don't mind about these details, it just makes sense to me@scalz said in Pre-assembled sensor modules:
If you tell me that your device with a precertified module is certified, I would ask you "do you have the certification paper of your device". If no, "do you have the tests results proving what you're saying?". No? So you didn't check it, it's not certified, it's just words :)
But those words bear legal liabilities. So if I break it down like this, and under the assumption I correctly understood the legal documents above (and maybe I didn't), it would go a bit like like this:
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Your own device with your own self-designed radio (like the OP) : You need mandatory full RF certification. Done by an external specialized certification body, you'll get all the paperwork proving your device is compliant. You also will have to pay lots of $$$ to the certification body and the FCC.
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Your own device but using a separate third party RF module with FMA, as they call it (full modular approval). You are supposed to follow the application notes to the letter. You are supposed to do your own compliance testing on your final device (or pay someone to do it). You will tell the FCC that you were a good boy, did all your homework and that your device does not modify the pre-approved RF modules behavior in a way that would make the entire device non-compliant. The FCC tells you, OK, we believe you and here's your registration number. But if you lied to us and / or didn't do the proper tests, then we (or anyone who feels like it) can sue you into oblivion (well, technically :grin:)
It's probably similar for EU certifications.
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@alex28 yes exactly, it may look exagerated but this is how it works. Same if you would replace the original wifi antenna on a commercial product. Like I said many times above, development boards (like OP design) can maybe fit in the "subassemblies" group, so mostly for development purposes only. CE is less strict regarding the process.
That's a while I looked at this, way before debating..Personally, I completely don't mind what people do, that's not my business. I just mentioned regulations as infos for those who are interested to know more. that's all.more links here:
https://www.sparkfun.com/tutorials/398
https://forums.adafruit.com/viewtopic.php?t=113747
