[rany_]

How are they doing SSL certificate management on an ESP32? Their article at https://khalsalabs.com/hosting-a-website-on-esp32-webserver-... makes no mention of how that would work, only really basic code for a static cleartext HTTP server. Is it even capable of such a thing?

Edit: I got a default nginx/1.18.0 (Ubuntu) gateway timeout message after a few minutes trying to load this page, this is reverse proxied.

[jcalvinowens]

An HTTPS server with esp-idf is absolutely trivial: https://github.com/espressif/esp-idf/blob/b4268c874a4cf8fcf7...

The software support is incredible IMHO, it's a huge reason to use these chips. I made some toy temperature sensors with an esp32 last year, they make it so easy: https://github.com/jcalvinowens/tempsensor

[constantly]

Very curious about the scaling process. I've been building something on a breadboard with an esp32 and I'm pretty happy with it. Now I want it to be a lot smaller, and in one piece rather than with a bunch of wires and components on a breadboard.

How do you make the step from breadboard dev to something manufacturable?

[jcalvinowens]

I didn't do any breadboarding at all, I just jumped off the cliff with this. I started by designing a 1"x1" PCB in EasyEDA with just the MCU and pin headers, and had five manufactured/assembled by JLCPCB to test the core of it. The first time I'd ever touched an ESP32 was when I got those PCBs in the mail and started trying to program them! It was really fun.

Once I'd proved it worked, I pasted that 1"x1" layout into a larger footprint, and added the sensor, power supplies, and batteries. Again, I had no real way to test any of the new stuff: I just iterated until I stopped finding problems to fix, then had them manufactured. A big part of the fun of this has been having to commit to a design without the ability to test: it really makes you think. I also enjoy the exercise of writing as much of the firmware as I can while the hardware is in the mail, then seeing how much actually works when it shows up.

In terms of bad decisions... I used builtin gpio pull-up resistors for I2C: it works, but the margin is very tight, it's just not worth it (and also means I can't put the ESP32 in sleep mode in some cases...). Wifi uses phase to encode information, so having no RF matching will impact its performance beyond the -6dB I mentioned in the README. The inductor/capacitor values are much larger than necessary. The routing of the I2C lines taking a huge bite out of the ground plane under the switcher IC is dubious. Using 1.5V alkaline batteries is nice because I don't have to worry about burning my house down... but I've gone through 200+ AAA batteries over the last year, and it feels very wasteful.

I learned most of what little I know about PCB design from this youtube channel, I can't recommend it enough: https://www.youtube.com/@PhilsLab

[anigbrowl]

Next step is a system integrator like m5stack.com, either build a nice unit from their library of components and let them worry about the minor issues (power regulation etc). If you're prototyping at home just put them in your own enclosure, if you want to go industrial you can 3d print something that integrates with their stuff (eg user-friendly modules like Core) or use the stamp components.

If you have done all the circuitry want to just print/assemble your own PCBs, sites like PCB unlimited will make up short runs or Digikey will handle larger scales.

[vinnymac]

I usually use https://oshpark.com/ or https://jlcpcb.com/ with EasyEDA or Kicad depending on what you're comfortable with. A good 3D printer wouldn't hurt either.

[_Microft]

What’s the project behind this? 30 assembled pieces are more than I had expected.

[jcalvinowens]

There was no real goal beyond the experience of building the thing and making it work. I use them to monitor stuff like fridge/freezer and HVAC intake/output, and as leak detectors in my crawlspace.

As you'd probably guess, the fixed cost of the manufacturing was extremely high. Unfortunately I didn't write the numbers down... but going from memory, ordering 5 instead of 30 would have only reduced the total cost by ~20%. I remember a weird valley in cost-per-unit at a quantity of 30: my understanding is that JLC combines small orders, so my guess is that 30 of that board was the largest order they were willing to squeeze onto the same panel as another one.

[barbazoo]

Even a 8266 would probably work for most people.

[schappim]

The error message "504 Gateway Timeout nginx/1.18.0 (Ubuntu)" suggests that Nginx, running on Ubuntu, is acting as a proxy server and is timing out while trying to connect to the backend server. The SSL cert is on the proxy server.

[declan_roberts]

So the answer is… they’re not!