https://opensprinkler.com/faq/ https://github.com/OpenSprinkler
I have a few of them connected to various wifi networks, and after a couple of years they always seem to disconnect and need a power cycle before they'll reconnect.
I understand they might lose the wifi connection, or their DHCP lease, or there might be interference, or something blasts too many packets at them, or a TCP connection hangs or gets RST... But after any of those, I expect them to recover, reconnect, and continue working. However, even a hello world web server on ESP32 seems unable to do that.
However, it's really hard to track down bugs that only happen once a year when I only have ~10 of these devices.
On some of them the WiFi would not work at all. Kind of like the onboard antenna was not properly connected. Other died after a few months without any special reason that we were aware of.
Another problem with these boards is that you do not know exactly the specs of the other components. For example we got different rated voltage regulators (5v to 3.3) that caused some issues because sensors we put on the 3.3v did have higher requirements.
Interestingly we had more issues with the "original" ones than the clones. I actually wrote a small blog post about it [1].
Another issue is that it is difficult to get proper ROHS and REACH certifications for these modules. This makes it difficult if you want to use them in a finished and certified product.
All of these issues added up and we made the switch away from the module and now put the ESP32-C3-MINI directly onto the PCBs of our indoor and outdoor air quality monitors. Together with an external hardware watchdog, this seems to pretty much eliminate all issues we had. If you are interested in the shematics, its all open source [2].
[1] https://www.airgradient.com/blog/d1-mimi/
[2] https://www.airgradient.com/open-airgradient/instructions/ov...
The other two I'm using (knowingly!) is with Flipper Zero, and they seems very reliable. But I wouldn't define those as traditional WLAN clients.
[1] https://thingpulse.com/product/espaper-plus-kit-wifi-epaper-...
[2] https://www.bresser.de/en/Weather-Time/Weather-Center/BRESSE...
if uping.ping('8.8.8.8')[1]==0: machine.reset()https://www.wemos.cc/en/latest/index.html
But the specific board from the post can be bought on Amazon:
https://www.amazon.com/CANADUINO-WEMOS-Minikit-240MHz-Blueto...
The challenge is that these modules are not all the same. The differences are for example in the voltage regulator and how much current you can draw from it. Which can make something work fine with one "D1-ESP32" while not working with another.
I am using the app based Espressive app based provisioning now and it's the best of the lot but still flakey on the Risk V chips like much of the IDF/Arduino wrappers. It's a hard problem.
Most of it works pretty well with the Extensa core so I suggest sticking with those.
https://www.nxp.com/products/rfid-nfc/nfc-hf/connected-nfc-t...
https://www.st.com/en/nfc/st25dv-i2c-series-dynamic-nfc-tags...
Maybe I'm just spoiled but it feels like I shouldn't have to go design something on PCBWay.com to get an esp with any memory above the 4MB flash.
Still, really powerful cool devices for their form factor and power needs.
Also, when a plunger gets stuck, the coil continues to draw a lot of current, and could burn up. This is a failure mode of solenoid valves in industrial processes. You can get DC solenoid valves, but the coils are bigger and they're more expensive. It means you shouldn't run an AC solenoid on DC unless you're really thinking hard about what you're doing.
And speaking of failure modes, another amusing feature of solenoid valve systems is the sheer number of ways that they can fail. One thing that's always counterintuitive to beginners is that a valve or its control circuit (or firmware) can get stuck in the "on" position. This is true of solid state and mechanical relays. A well engineered system plans for this possibility. "Stuck" could mean releasing a lot of energy (e.g., if controlling a heater or motor), or flooding your garden, or your house.
Also, AC is easier to switch with physical switches, and there's a ton of stuff still using physical relays at low voltage. It would be nice to go DC but there seems to be inertia.
The exception is 'dumb' solenoids, valves, pumps etc, which are actually powered by the 24Vac.
We also rate AC voltage by RMS, which (for resistive loads) is the voltage that would transfer the same amount of power as the DC equivalent.
But really the peak voltage is higher, so we need parts with a higher rating despite the fact we are not using that peak the whole time.
And then there's issues with power factor. Modern gadgets don't draw power in the nice sine wave pattern without extra tech to make that happen. The extra tech is common now, but isn't needed with DC. Without PFC, you get more line resistance losses than you want.
But now we have solid state switching, and it's cheaper to convert DC with a SMPS than a bulky transformer.
We also don't use long series circuits commonly in anything I know about, except for Christmas lights, which are mostly LED now and work fine as they are(As long as nobody forgets a smoothing capacitor to get rid of that horrid flicker the cheap ones have).
Series circuits have the same current everywhere, but modern stuff is constantly changing the current it draws to save power. Which would be an issue if one device wants to be in sleep mode but the other wants to be full power.
I suppose we could do series circuits with constant current power supplies, so the supply pushes a constant 1 amp, and the devices alter their voltage drop to draw more or less current, rather than altering their current draw.
AC seems to be more suited for higher voltages(Where arcing is a problem) and analog stuff(if you don't want to use SMPSes and you have resistive loads to drive).
AC also has WORSE voltage drop than DC because it exhibits something called the skin effect that causes the middle of your cable to not be used as much to carry current.
Tesla triumphed over Edison because we didn’t have the technology to step between voltages back then. DC transformers are still incredibly expensive. AC transformers are coils of wires.