[kogepathic]

This looks quite similar to the Sonoff S20. [1] Although they opted for the ESP module instead of designing a custom PCB around the ESP8266 chip as Sonoff does.

According to the S20 schematic, uart is routed to a header, so it should be easier to flash. [2]

The Sonoff S20 is the same price as the mentioned model, and is supported by espurna. [3] Espurna is great, it has MQTT, Domoticz, Home Assistant, an HTTP API, and Alexa integration. Espurna also supports sending data directly to InfluxDB which is very handy.

If you want to monitor power consumption as well, I can highly recommend the Sonoff POW. [4] Although to get a plug you will need to butcher an extension cable or power strip. If you only want to monitor power consumption and don't want to have the relay, it's quite easy to solder across the relay in the Sonoff POW and use it only as a power monitoring device.

Just a reminder to anyone working with these devices: never, ever connect UART while the device is plugged into AC!!

[1] https://www.itead.cc/smart-socket.html

[2] https://www.itead.cc/wiki/S20_Smart_Socket

[3] https://bitbucket.org/xoseperez/espurna/wiki/Hardware.md

[4] https://www.itead.cc/sonoff-pow.html

[luma]

I'm also a fan of the Sonoff products for random use cases around the house. One thing I think should be noted - you no longer need to solder in a UART header to get your own firmware on Sonoff devices with the SonOTA project [1]. This project uses the factory OTA mechanism to load your own custom firmware on the device. The result is an IOT device that is cheap, readily available, and fully under your own control with no hardware modifications necessary!

[1] https://github.com/mirko/SonOTA

[joelhaasnoot]

Perfect, just used this to hook up my Christmas lights. Had an opened Sonoff device laying around that I had yet to flash. Put screws in and 5 minutes later had my lights working. Much easier than the 4 pin serial flash solution

[StavrosK]

Thank you for this. You just saved me lots of disassembly.

[lucaspiller]

It should be noted that Sonoff devices are not UL Listed, unlike the device the article discusses. Given that and how Chinese product companies like to cut corners with these type of devices (see bigclivedotcom on YouTube), I’m not sure I’d trust connecting one of these to mains voltage.

[janekm]

From looking over their schematics and layout, they are fairly well designed, and they have gone through CE certification so fine for European consumers.

No UL certification could be an issue for US consumers though.

[IgorPartola]

I understand CE to basically be self certified. It’s good but mostly meaningless when compared to bring UL listed or higher, which require equipment tests as well as frequent drop in visits from UL people to your manufacturing fascilies.

[janekm]

They have undergone testing by a third-party test house for their CE certification. While you're right that in many cases CE can be self-certified, this is not (really) the case for mains equipment, the testing required by the European standards are such that it would be difficult to perform yourself.

[amelius]

> never, ever connect UART while the device is plugged into AC!!

Why?

[nitrogen]

If I remember right, some very low cost ways of converting AC to DC for small electronics leave those electronics at high voltage relative to ground. So the device itself sees +5V relative to its "ground", but the device "ground" might actually be at, say, 115V and the supply at 120 to make 5V. Thus the UART pins might also be at high absolute voltage. This is fine for devices that are fully isolated.

[janekm]

The "POW" device is one example of a device which has GND at live potential, so should not be connected to anything else while plugged into the mains.

Not that I would recommend plugging any of them into the mains with the case removed, or while plugged into other wiring, to be sure!

[amelius]

> The "POW" device is one example of a device which has GND at live potential

Is that even allowed by the FCC?

[detaro]

Yes, that's a quite common design. It might be forbidden if you expose that outside the device, but in electronics internal to the device you can do that no problem.

[amelius]

It sounds to me like the ground level is exposed outside the device in this case.