I ordered PCBs from JLCPCB and components from LCSC. I think each one cost around $5 in parts, and I hand-assemble them as I need more around the house.
https://github.com/sowbug/smart-usb-switch
Picture: https://raw.githubusercontent.com/sowbug/smart-usb-switch/ma...
I used ws2812b leds, wemos d1, and a level translator since the d1 has 3.3v gpios but ws2812b technically requires a 5v signal.
How certain are you the fish can't see the PWM?
I need to build a custom board for an ESP32 which should support low-power deep sleep and which should contain some additional circuitry (is that what you call it?) to drive an Eink display.
Basically this[1] board, but a different shape and better low-power sleep properties.
If I wanted to design this board myself, how long would it take to learn this? Are there good resources?
If I were to pay somebody to do design this, what order of magnitude would the cost be in?
> https://eckstein-shop.de/Waveshare-Universal-e-Paper-Raw-Pan...
I really recommend it, designing PCBs is very enjoyable (at least to me).
To learn it yourself, assuming no prior experience or knowledge, would take years of full-time study.
With those schematics and KiCAD, you should be pretty much set. Take an hour or so watching KiCAD tutorials, it'll be worth it.
Also, spring for an ESP32-WROVER-KIT and use it to prototype with a dev board. That kit also supports JTAG debugging, which can be quite handy.
I recommend you to check that out.
A few questions:
* Should the relay have some sort of isolation, like an optocoupler?
* Is it FCC-certified?
* Like other people asked, any information on how the antenna was designed?
I like the old-school dome LEDs. And it's cool to see another project with a CH340 USB/USART bridge, even if they wouldn't need it with an ESP32-S2.
I convinced my boss to let me sell these as open source since we found many cool IOT uses for them around the office as well, that's why you are getting the RS232 on there but most people probably will not need that feature, but hey... it is there if you need it :)
Esp8266 doesnt have flash encryption and secure boot. Esp32-s2 does though.
rs232 can run quite long distances.
https://www.amazon.com/dp/B08GY2GTW5?ref=myi_title_dp
I'm curious about availability. Are they ready to ship? Awaiting preorders?
EDIT: Oh I see 18 in stock. Probably remains of a small run to gauge interest. I hope it takes off. I'm going to make it 17. :-)
Are you planning to sell a case to go with it?
Almost like one from here: https://www.ti.com/lit/an/swra351a/swra351a.pdf
Also I wish it was available in Canada.
But you can also do so much more: these chips have lots of GPIO pins so you could control anything that an Arduino or another microcontroller can control such as relays, displays, temperature/humidity/proximity/etc. sensors, LED strips, motors, heaters, and so on. But the kicker is that with built in WiFi so you can natively get it online. A lot of smart lights now have these chips in them for example and you could make your own. Or your own internet connected green house with vents you can open/close and sensor readings for temperature and humidity in the air and the soil. Or an RC car you control from your phone. Or shades that open and close based on time of day. Or a garage door opener. Basically if you need a gadget you control over a network, these probably should be your first potential solution. They are low power and physically small compared to something like Raspberry Pi’s or other single board computers and more powerful than Arduinos.
I've mostly been looking at the ESP32, though (newer, also has bluetooth and 2 cores, and is lower power), and some of the ARM Cortex-M-based microcontrollers.
As the device has onboard WiFi I can poll a remote site to get data and display it, updating every few minutes. I use that to show the next departure-times at the tram-stop round the corner from my house.
Sure I could use an app, or even walk there and wait, but it's nice to know when to leave - especially in winter-time!
Alexa enabled switch to turn on / off a TV using the IR blaster
my boss used 3 of these this to build a smart sprinkler system for his house.
It makes me wonder if there’s interest in more of these type ofESP* dev kit boards. One I haven’t seen is one with just Ethernet PHY but no Ethernet jack/magnetics. It’s been useful in my designs to have a ETH+/- that can be brought out to various Ethernet / PoE setups. Something like the wESP32 is handy for kits but not for integration.
I have hacked something on a protoboard for nodemcus before, but it ended up being pretty messy.
$19.99 seems a bit expensive to me though.
Is there any intention to add WiFi support to the dev kit?
The relay would just be used as a switch to turn on/off an external device using higher voltages, AC or DC.
What is an "ESP8266 board"? Is that something that is so common it doesn't need explaining? Of course I will google it [and probably buy one], but just pointing out that it's not very clear from the website!
[EDIT: ok, after 10 minutes of googlin', it seems no one will explain what it is - it's just "an esp8266 system on a chip". It must be the first rule of ESP8266 club...]
https://omronfs.omron.com/en_US/ecb/products/pdf/en-g5le.pdf
Though it does look like the clearance/creepage distances on the PCB to the low-voltage ground plane are not any wider than 2mm or so, which is acceptable for 120VAC, but not acceptable for 240VAC per IPC9592.
I wouldn't worry about sticking this in an enclosure and using it to turn a light on and off, but I wouldn't want to be handling it while it was live, either!
Regarding FCC/UL certification, a product is exempt from FCC certification requirements if it's "A digital device used exclusively as industrial, commercial, or medical test equipment", which most development boards are. I've got some dev boards from Microchip on my bench right now which aren't FCC or UL listed, either.
> (k) Digital device. (Previously defined as a computing device). An unintentional radiator (device or system) that generates and uses timing signals or pulses at a rate in excess of 9,000 pulses (cycles) per second and uses digital techniques; ...
https://www.govinfo.gov/content/pkg/CFR-2009-title47-vol1/pd...
This has Wi-Fi, so it's an intentional radiator, so it's not a digital device. I believe this product would be technically noncompliant if not certified, though lots of stuff like this gets sold and I've never heard of any enforcement action.
Their best counterargument would be that it's a component and not a self-contained product. That seems true for many dev boards but not particularly true for this one. Since the practical risk of interference is extremely low, I'd guess the FCC is happy to leave this grey for now.
It would certainly appear to lack the FCC ID label/marking it is required to have if it is FCC certified. So probably not. Thus, it also appears doubtful whether it can legally be marketed or sold in the U.S.
In addition, this product lacks a CE mark and has no UL/FM/CSA listing. I'm curious what creepage/clearance requirements were factor into the design. This product is potentially dangerous if the relay is switching line voltage.
I got 3 units built for myself by PCBWay at a cost of $77. I got quotes of ~$500 for 100 units from Elecrow and Makerfabs, but didn't know what to do with the other 90.
Although I really want this great little gadget to be easily available, I can't afford $10,000 for FCC certification, and therefore I have no solution.
If anybody wants more details, email espusb@gmail.com and we can chat about it on there.
If it doesn't have a shield, it's almost certainly not FCC certified.
If it does, it's more likely to be certified.
It's a bit harder to get started with than your average arduino project. If you want, you can use the Arduino IDE which hides a lot of the complexities. But the docs from espressif are aimed more at the firmware engineer crowd, so if you want to get serious there's more of a learning curve (IE nvflash partitions, understanding what a bootloader is, etc). Also, you'll probably end up getting into freertos at some point, which further complicates things. But it's a super great module for home projects.
The esp-32 is a newer chip which is similar but adds bluetooth. In general you're better off going with esp-32 nowadays -- it's got a second core as well.
Until recently the only thing missing was USB (though there were bit-banged USB implementations!). But now there's an esp-32 with USB too, so really for the cost, the features are unparalleled.
If you're okay with things not being as polished as the Arduino experience (you might have to learn "real" firmware programming), it's really the best starting choice for your side projects.
The older board didn't have integrated USB, which made the dev process annoying.
It's a basic 32bit RISC microcontroller, generally running at 80MHz, with built-in WiFi support. They're often available as modules with either a pin header or castelated edges for surface mounting.
They are supported on the Arduino platform and Platformio.org, as well as some other platforms. They've become quite popular due to their low cost (often available for under $10 at individual quantities) and the fact that they include wifi.
I have two rows of 32 lights, so a beefy supply was needed along with a few places where VIN was fed to the strip.
I have the opposite experience. Sure, if you just need to adapt their examples a bit, it's quite smooth. But the documentation is horrendous! If you need to do anything non-trivial that isn't covered by examples, I found it very very hard to work with. The documentation barely exists and is written in poor English. Compare this to the documentation for ARM SDKs, for example! Night and day.
esp-idf worked on the first try.
[1] https://docs.platformio.org/en/latest/what-is-platformio.htm...
Ethernet: https://github.com/cnlohr/espthernet
PAL TV: https://hackaday.com/2016/03/01/color-tv-broadcasts-are-esp8...
I haven't yet seen an FM transmitter though, but it's been done on the Raspberry Pi GPIO so I guess it could be done on the ESP also.
On the one hand, I have a bit of prior knowledge. On the other hand, I want a circuit with minimal power draw in ESP32 sleep mode and i’m afraid that does require some experience.
There are other microcontrollers capable of driving an eink display that consume a lot less power out-of-the-box. Eg: atmega328 (~5 μA deep sleep, ~10mA running)
If you want wifi, then ESP is probably a good and cheap fit. A wemos d1 in deep sleep doesn't consume _that_ much power (~80 μA), unfortunately it does draw a lot when booting (~200mA).
I drive the wemos d1 and led’s from a 12V battery with a 12-5V stepdown converter. I attach the 5V to the esp and the led’s. The 3.3V logic level works on the first led and is repeated at 5V to all subsequent led’s.
The power lines do sustain voltage drop over longer sections, so you'll want to add extra power every few meters.
"Based on the definition above, it looks clear that non-authorized kits that are intended to form a complete product when fully constructed are technically not legally permitted to be sold in the US. That is because if you are marketing and selling a kit to an end user, which the user will then build into a full product, there is no reason to suspect that the normal rules would not apply."
The subassembly rules could work, if they apply, but I don't see how this product fits the definition of a sub-assembly:
"No authorization is required for a peripheral device or a subassembly that is sold to an equipment manufacturer for further fabrication."
In fact, I think it's a stretch to say that any of these test-kit, dev equipment, or subassembly rules apply. This basically strikes me as being marketed as a consumer product -- albeit a product for very tech savvy consumers.
Certainly there is ample precedent for other dev boards (intentional and unintentional radiators) being sold without certification.
If you have never sought certification know that it is quite expensive.
What seems to matter the most is if anyone actually notices interference, and if they do how widely the device ended up being sold. If a test and measure product starts making it into everybody's house eyebrows will be raised.
If you misuse a test and measurement device and generate interference it is typically on you.
On what authority are you claiming this? The language LeifCarrotson quoted refers only to digital devices, and the language I quoted above says plainly that a digital device must be an unintentional radiator.
To be clear, I believe selling their dev board is fine, but it's fine in the same way that driving 60 mph in a 55 zone is fine. Anyone selling an intentional radiator dev board that could reasonably be considered to be a complete device in itself is taking a small risk of FCC action, especially if (as here) they're pushing the limits of "dev board". Note that the Raspberry Pi developers do seem to get certs.
https://www.raspberrypi.org/documentation/hardware/raspberry...
My opinion comes from experience and getting things certified but also common sense and observing enforcement patterns (the latter of which is most important until they overstep and get challenged).
Go back to my example: Does a one-off product need to be certified to be transferred to the people that paid for it? Keep in mind, best case, this will add a roughly >$10k fixed cost to the sticker price.
It's a general principle in common law that the law makes sense. The popular, sophomoric, and extremely conservative interpretation of the FCC rules makes no sense by way of being extremely costly for no discernible benefit, either to the seller, the buyer, or the economy at large.
There are things that are battery powered that need to be certified and things that are not kits that don't need to be, though, so I'm not sure I can agree with that wording.
But 47 CFR § 2.803 gives an exemption for "evaluation kits". I don't think that clearly covers boards used primarily as single-board computers (and not genuinely for evaluation), and I'd guess that's why the Pi developers got certs for their boards. I believe it's the best argument that this board wouldn't need certification (or verification), though.
Then you can order your PCB at a local shop, manufacture it yourself (with toner transfer, a CNC at a hackerspace, etc) provided the traces aren't too thin and there are not too many layers (1 is easy, 2 is standard and cheap, more layers are expensive), or order it from china at a relatively low price (jlpcb or seedstudio will average something like $1/apiece).
PS: And yes, while I really suck at soldering, working with physical products feels like a nice counter weight to the software world.
The trick to soldering is really to get a good iron, I underestimated it at the start but you really need something that keeps heat. Get a TS100 and set it to 320, soldering is going to be a breeze afterwards.
Remember, solder should flow easily and stick to the pads/wires, if it doesn't, it means you need to heat the thing up a bit more.
It’s really weird. Maybe I messed up the tip somehow? But I just got it a few days ago!
As you add more LEDs you have a greater chance of one at the end not lighting up or having incorrect colors throughout the string.
0.7 * 5v == 3.5v, and 3.3 < 3.5. You're out of spec for the part and can't expect it to work reliably.
I'm working on an ESP32-based product that doesn't use sleep mode, but I've noticed people reporting issues about sleep mode on GitHub and in forums.
That's not how it work. You start by selling them, prove the concept, and when you have the money, you sort out certifications & whatsnot.
You won't become a unicorn if you think about doing everything _by_the_book_ from day one.
An intentional radiator module can get a module certification. In that case the final system still needs verification (the same kind of testing that an unintentional radiator gets), but doesn't need certification. When you see a label on the outer device that says "Contains FCC ID XXX-XXXX", that's the module's ID.
https://apps.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm...
ETA: And here's the section about battery-operated digital devices (i.e., unintentional radiators, with no radio transmitter):
> § 15.103 Exempted devices.
> [...]
> (h) Digital devices in which both the highest frequency generated and the highest frequency used are less than 1.705 MHz and which do not operate from the AC power lines or contain provisions for operation while connected to the AC power lines. Digital devices that include, or make provision for the use of, battery eliminators, AC adaptors or battery chargers which permit operation while charging or that connect to the AC power lines indirectly, obtaining their power through another device which is connected to the AC power lines, do not fall under this exemption.
And here's the section that makes it fine to build your own stuff in limited quantity, as long as you don't do anything obviously stupid:
> § 15.23 Home-built devices.
> (a) Equipment authorization is not required for devices that are not marketed, are not constructed from a kit, and are built in quantities of five or less for personal use.
> (b) It is recognized that the individual builder of home-built equipment may not possess the means to perform the measurements for determining compliance with the regulations. In this case, the builder is expected to employ good engineering practices to meet the specified technical standards to the greatest extent practicable. The provisions of §15.5 apply to this equipment.
The iron is a LONOVE 925 m.
By law, that one-off intentional radiator absolutely does need to be certified. The FCC's enforcement priorities will be different depending whether that product is a little 2.4 GHz radio or a television transmitter, but their enforcement discretion doesn't change the law. Anyone who wants to be compliant needs to pay for the testing (or use a certified module, which is often easy and cheap; I've done that several times myself).
Lots of people disregard lots of laws because they're too expensive to comply with. Most of them get away with it, and a few of them get nasty surprises. I believe that I've given both the correct legal advice and a correct description of typical (not fully legal) practice. It's not helpful to conflate the two.
Large companies, small companies that want to get bought by large companies, and other conservative entities generally aim to comply with the law as written, even though there's lots beyond that you can probably get away with. Everyone should judge for themselves how far they want to push from clearly legal actions to grey to clearly illegal but unenforced; but they should know which one they're doing, and your advice isn't helping.
If we submitted a KDB inquiry asking the FCC whether the board in question required certification, what do you think they'd say? (It's free, and you typically get a quite competent response within a few days. If anyone wants to try, please use a generic description, and not a link to the particular product. I doubt the FCC would waste their time enforcing, but the chance isn't zero and the developers don't need that attention.) Or why do you think the Pi developers got certs?
I generally aim to comply with the law as much as possible as well, but the people in this post (including yourself) seem to have no idea of the true cost of complying with the interpretation of the FCC rules you are putting forth.
Yes, if you ask the FCC whether it requires certification they would probably say yes, mainly because they do not want to undermine their authority. This is something I've dealt with quite a bit with pretty much any regulatory body; they pick the most restrictive and burdensome interpretation regardless of what common sense or existing or future court cases eventually say.
In the past, I've done other stuff less strictly (though again, certified modules--which you didn't seem to be aware of--are the quick, easy and compliant answer for many low-volume products). I was under no illusions that anything but the FCC's enforcement discretion was protecting me, though. Your concept of the law is simply wrong, wishful thinking. It seems there's nothing I can write that would convince you of this; but please discuss with a lawyer or other qualified person that you trust, before you or someone you're advising gets in to serious trouble.
Your viewpoint is particularly dangerous because if you look through the FCC's formal enforcement history, you'll see occasional massive fines, but only after the noncompliant entity ignored multiple attempts to resolve the matter informally. Anyone who acknowledges and corrects their noncompliance after the first threatening letter probably gets a slap on the wrist at worst; but someone who persists under the belief that a judge would let them disregard the text of the law to save $10k will (a) incur much greater legal costs regardless of whether they win or lose, and then (b) near-certainly lose.
You could say this system gives too much weight to the regulator's own interpretation of its rules. I wouldn't disagree; but it's how most regulation works, and the regulated ignore it at their peril.
That's nice. Are those the only types of businesses who can enter the market? I'm also aware of modules, but using them is not free.
Your concept of the law is more wrong, and this I offer as proof: Language is imprecise and limited. It is more likely that the text of the law fails to track the intent of the law than otherwise.
Throughout this I have never said I would disregard a notice that a product I had made was emitting or otherwise faulty, and indeed I believe that is the first check on most low volume products that are sold "without certification."
To behave otherwise, and allow the prior limiting of otherwise benign and nondisruptive behavior, is to give in to petty tyranny and against the founding ethos of the United States.
Seriously, this is like arguing with a sovereign citizen. The law isn't just some abstract philosophical ideal. The law is the set of rules that determine how the government exercises its hard power, including the power to block import of your product, seize money from your bank account, or, ultimately, send police to arrest you, with any necessary violence if you resist. EMC regulations tend to stay pretty far on the polite side of that spectrum; but the result when people with a delusional concept of law meet actual government power still typically isn't good.
Can you give an example of evidence that would convince you that your concept of the law is wrong? As I said above, you could show me case law where the text of the law was unambiguous and not preempted by other written law, but the judge disregarded it anyways. What could I show you?
ETA: And you moved the goalposts when you said you wouldn't disregard "a notice [from the FCC] that a product I had made was emitting or otherwise faulty". An uncertified intentional radiator is noncompliant, regardless of whether it conforms to the technical limits. The FCC is under no obligation to confirm anything beyond the lack of certification before ordering the product off the market. We're talking about the requirement for certification, not the requirement to meet the technical limits (which the certification confirms; but meeting the technical limits absolutely is not a defense to lacking certification).
So if the FCC just said "your product is uncertified, stop selling it", would you comply? If no, then I think you know bad things would follow. But if yes, then why? You seem to believe (contrary to the guidance you expect from the FCC, and contrary to the text of the law) that no certification is required, right?
See this in yourself as your second paragraph details all the ways the government is scary. Yes, I already know.
I can't think of an example because I know my concept of the law is not wrong. Do not mistake my philosophical groundings of what and why the law is for what I believe the law to actually be. I offered that explanation to you in an attempt to explain why I think what I do and why it is reasonable while also referencing particulars.
What we are discussing is particulars, and if you want to show me that selling low volumes of a product without certification is dangerous then probably I'd need a few examples of that happening, and multiple justices saying "every business, regardless of how big, small, or their product, must spend tens of thousands in red tape."
I did not move the goalposts by saying I wouldn't disregard reasonable notice. You assumed I would not without asking my input and I corrected you.
It depends on what my product is. If it was a low volume prototype I was selling to evaluators before certifying in detail I'd probably say "no, it is certified, it is test and measurement equipment" and then let the company fold in bankruptcy if taken to court. Eventually it may be found the actions of the FCC were unlawful and I might be compensated. If I was intent on immediately continuing to sell it I would move production outside the US and put it on a web store.
Keep in mind you've unfairly characterized what I believe by assuming things in multiple places. I am not a sovereign citizen, and I mostly agree the FCC certification process is appropriate and on the edge of being accessible, but how most people interpret it at the lower edge is not correct.
So when you write:
> If it was a low volume prototype I was selling to evaluators before certifying in detail I'd probably say "no, it is certified, it is test and measurement equipment" and then let the company fold in bankruptcy if taken to court. Eventually it may be found the actions of the FCC were unlawful and I might be compensated.
you have broken from reality. Any lawyer you engaged to defend you would explain that you have a losing argument, and that it would be far cheaper to comply than to pay their fees and then lose. Without a lawyer defending you, your odds would be yet worse. If you won, then you'd be lucky to get even a fraction of your legal fees awarded, let alone the lost profits. In every practical sense, you'd be worse off than if you recognized that while the requirement for certification isn't typically enforced, that's nonetheless the law, and that your best action would therefore be to apologize (with a lawyer's help, to avoid admitting any unnecessary guilt) and become compliant.
I'm not saying any of this is good! Enforcement discretion is basically bad, a transfer of power from legislators to enforcers. I'd prefer a system where something like the § 15.23 exemption applied to low-volume commercial products too, since that's what we de facto have and it works fine. But that's not the law now, and wishing doesn't make it so.
You're quite correct that lawyers give conservative advice because they know the cost of conservative compliance is generally lower than the cost of litigation even if you win. The lawyers that I work with sometimes find my tendency to read the regulations to be charmingly naive, because they prefer to simply ask the regulators--in part they're just a bit lazy, but they're also quite aware of the cost (both in legal fees and in friendliness of relationship) to take any conflicting position. I'm again not saying this is good, but it's the system we have.
Finally, if you did want to argue this, I believe you'd be better off saying it's an "evaluation kit" under 47 CFR § 2.803, not "test equipment":
https://www.law.cornell.edu/cfr/text/47/2.803
Per my original comment, I'm not convinced that's a winning argument for this board; but I believe it would be for typical dev boards (that really are used primarily by people evaluating a part for use in a different system, and not as general-purpose single-board computers), and it's at least not a frivolous argument. Note that compliance with the "evaluation kit" rules requires some magic language in the user manual--if you're selling anything that could plausibly fall under those rules, probably a good idea to include that. Note also that you can let customers evaluate unauthorized prototypes as long as you mark them accordingly and don't collect money for the evaluation, and that you can sign a sales contract (but not complete the sale) pre-authorization as long as it's contingent on authorization.
