Pre-assembled sensor modules



  • Hi,
    Thank you for what you are doing. MySensors is great!
    But to me it sounds a bit to difficult for people who don't know very much electronics.
    Their only alternative is to go for a commercial solution. Seems there is not much in between.
    In your presentation page, you wrote : "we are working on launching our own set of sensor modules and boards to ease the build process even more"
    Any progress on this? would be nice to get sensors ready to use out of the box. Or at least ready with minor operation...
    Do you still plan to release your sensors? and what timeframe?
    Bye!



  • I would though image price gets too high if those are sold as pre-assembled. (These devices are hand made, and not manufactured by a real manufacturing line that manufactures thousands per day) Are you able to solder? I think most of the guys developing HW here are willing to sell off their PCB, so you "only" have to solder connectors and a few lead through components to the PCB to assemble the PCB together.
    If you are not able to handle soldering, then search for the nearest Fablab in your area, as there are skilled people that most likely are willing to teach you how to solder: https://www.fablabs.io/

    This could be a good start:
    https://forum.mysensors.org/topic/2740/easy-newbie-pcb-for-mysensors

    More good stuff to be found via this link:
    https://forum.mysensors.org/category/30/openhardware-io


  • Admin

    There is actually two "products" that are sold.. Not complete with plastic box etc. And you have to solder a socket for the radio, and add the radio yourself, as well as do a bit of programming, but the SMD parts are already mounted. I think that this is the closest that you come to a pre-assembled unit these days.

    Sensebender gateway - Can be bought from Itead
    Sensebender micro - Can be bought from Itead



  • Hi! thank you for the answers. I personally have the expertise and I am able to solder. I was thinking of people who just have basic or no knowledge about electronics. It is always a pain to get a working initial set up. In case of communication issue (which is always the case at the first try) you never know where it comes from. Is it the node? is it the gateway? is it hardware? is my code correct? is my power supply correct?
    So I've decided to design a minimalist board that embeds an ATMega328p low power and an nRF24L01p: just the bare minimum. The purpose is to provide a functional board that works for sure out of the box. Actually it is an Arduino Pro Mini fitted with a radio module. The pinout is 100% compatible with Arduino Pro Mini. Users won't have to spend time on assembling the parts and testing the radio, they can directly focus on their sensor.
    Design files are available here.
    I also created a kickstarter just to see. You can buy one or more units and support the project if you are interested.
    I don't know much about openhardware.io but I guess I can share my project there as well.


  • Admin

    @echi nice product, but what about rf conformity of the radio? Is there any fcc / ce approval? It's not enough to just slam a radio chip on a board and sell it (unless you are a cheap Chinese eBay seller ;))

    That is one of the main reasons to why I did not incorporate the radio module with sensebender micro, as I do not need to make any radio measurements.

    /Thomas



  • thank you! this is a really good question. I now understand why you didn't incorporate the radio module. Is it the only reason? Have you investigated ways to certify a product? It is a pity if you can't incorporate the radio but we need to add extra modules that are probably not certified either. I am not willing to become a vendor (just providing a design and a few units). In that case, I don't think I need to make any measurements. Of course if one wants to go further in the industrialization process, it is a mandatory step.



  • thank you! this is a really good question. I now understand why you didn't incorporate the radio module. Is it the only reason? Have you investigated ways to certify a product? It is a pity if you can't incorporate the radio but we need to add extra modules that are probably not certified either. I am not willing to become a vendor (just providing a design and a few units). In that case, I don't think I need to make any measurements. Of course if one wants to go further in the industrialization process, it is a mandatory step.



  • @echi Have you checked the price for getting the FCC and radio approvals? it's quite expensive. As it's mandatory to have an independent test company to do actual test on your devices as a part of the documentation. Furthermore you need also to get country approvals (Notified Body) for several countries where you want to sell you product, fortunately as I recall EU only requires approvals in 1 country to be valid in the rest of EU countries.

    This link is from 2014, but gives you an idea what kind of approvals that you MUST get prior selling your stuff
    https://www.quora.com/What-is-the-average-cost-to-get-FCC-and-CE-certification-for-a-very-simple-electronic-gadget?share=1


  • Admin

    @echi the thing is, that if you design/sell a board with an radio incorporated, then you are obligated to get fcc certification (for the US), and other approvals for the rest of the world, as @bjacobse explains.

    But if you do not include the radio module, then it's not your problem if an end user use a cheap Chinese radio module together with your product.



  • So what do you think of the cheap radio modules? Are they certified? Some are sold by sellers based in Europe. Is all this illegal?


  • Admin

    @echi for my part I'm not concerned about it, because I'm not the designer/seller of those modules. So if the notified bodies find that they are not compliant, then it's not me that they're gonna bug about it.

    It's all about responsibilities. I'm not making a radio module, so I'm not responsible for the rf part, and as such, they can't sue me for that part.

    / Thomas



  • @echi Basically it's quite simple, it's the whole device that needs to comply to the rules, and not ONLY the radio-part of your design.
    so it's not possible to "buy" a radio approved RF IC and then add this to your own design, and then think this is adequate



  • I understand your point. But in the end almost everybody uses non certified radio parts. And a lot of users around here are frustrated because of the hardware issues due to bad radios. That means a lot of wasted time, also for the helpers.


  • Admin

    @echi We are just pointing out potential pitfalls if you are going to sell your pcb pre-assembled to the masses..

    That is, if you are selling a PCB with radio on, then you are obligated to follow the rules and get the radio verified by a notified body.


  • Mod

    Congratulations on meeting your kickstarter goal @echi



  • @echi it's too expensive as you can get one from AliExpress a lot cheaper.
    #Aliexpress £3.33 | Keywish RF-Nano for Arduino Nano V3.0, Micro USB Nano Board ATmega328P QFN32 5V 16M CH340, Integrate NRF24l01+2.4G wireless,Imme
    https://a.aliexpress.com/_dYIhsQZ



  • @Phil-Whitmarsh said in Pre-assembled sensor modules:

    @echi it's too expensive as you can get one from AliExpress a lot cheaper.

    Yeah and that one is guaranteed to be 100% counterfeit and 100% crap.

    A module such as the OP designed would have really helped me when I attempted to setup MySensors (see my other thread). I definitely would have bought it. Simply because having a guaranteed functional module with guaranteed original components and certified RF performance is a great selling point. Who cares if it costs a few Euros more. How much do you value your time ? This obsession of always wanting to use the cheapest of cheap low quality stuff from China really puzzles me. You end up spending so much time with a barely functional setup just to save a few bucks. So that's a great initiative @echi .

    About certification. This is obviously a must have. But I was under the impression that when all your RF circuitry (including PCB antenna, if any) is isolated on a separate third party module that was certified (like for example this one, they claim FCC certification in their specs), then you could use it in your own design without having to reapply for RF certification. Am I wrong ?



  • @alex28 This is the same seller I have used for many of my purchases AVR's, STM32F's etc. When you're buying hundreds it's not just a few bucks! AliExpress are really good, any issues and you get a refund in a couple of days.

    I have only had a couple of issues with my hundreds of purchases over the years.


  • Admin

    @alex28 It's always the complete product that you need to do certification on. It will probably be easier with a complete module, as the rfm69, but a lot of things can change the RF characteristics. For example the ground plane layout on your own board, chosen MCU, xtal frequency, decoupling etc. and firmware...


  • Hardware Contributor

    @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 😀

    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.


  • Hardware Contributor

    @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?



  • @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.



  • @alex28:

    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.


  • Hardware Contributor

    @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).



  • @alex28

    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?


  • Hardware Contributor

    @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:

    • 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.

    • 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 😁)

    It's probably similar for EU certifications.


  • Hardware Contributor

    @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


Log in to reply
 

Suggested Topics

  • 2
  • 2
  • 7
  • 3
  • 8
  • 10
  • 14
  • 961

189
Online

9.5k
Users

10.1k
Topics

105.1k
Posts