Imagine Sonoff Basic R3 (review) or Sonoff Smart Socket (hacking guide) but for USB ports. Is it an outlandish idea or is it something that is actually practical and useful? Sonoff Micro works like any other Sonoff switch, except, it manages USB-A instead of mains power supply. It’s also a device that carries a small secret.

Sonoff Micro for your USB ports

Right from the start, everyone’s question is: why not to use the smart socket instead – like Sonoff Socket? Price is probably one of the reasons as Sonoff Micro retails for $6.45 on the Itead Store which is about half of what would you pay for a smart socket.

The immediate argument would be that the smart socket is more practical, but if you have a specific USB use in mind, Sonoff Micro could be an option.

Like any other Sonoff

This IoT switch works like any other Sonoff device. I’m not sold on QR pairing method, as you have to keep the unique QR label, but it worked flawlessly. Once paired, Sonoff Micro appears among other eWeLink devices.

You have access to the usual settings – timers, schedules, inching and notification when the switch is in use. Since the eWeLink app is integrated with Google Assistant and Amazon Alexa, you can toggle it with simple voice commands.







There is a button to change the state and rather small and dim LEDs that display the relay state and the device status. These could be much brighter if I’m honest and they are barely visible in the broad daylight.

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There is one thing missing…

There are limitations that you have to be aware of. The biggest one is – no data pass through. Sonoff Micro uses BC1.2 charging protocol. It uses data lanes D+, D- to negotiate the charging current and boost it up, but sacrifices the data transfer in the process.

You can turn things ON and OFF, but you can’t pass data via Sonoff Micro. It’s a shame.

Power delivery

There are no bells and whistles here either. Sonoff Micro is capable of 2.4A current, no Quick Charge or other protocols than BC1.2. Since there is no USB-C socket, and there is way too much space inside it, I decided to add a USB-C port myself! You can read about this project in this article: Sonoff Micro PLUS.

Inside

Sonoff Micro is hard to open, unlike other Itead products. Inside, the switch is amazingly small! Unlike other Sonoff products, this gadget isn’t ESP8266 based – it uses a new to me CKW04 marked with an eWeLink support label.





There is very little online about this IC. It’s going to be a while before we will see custom firmware available, so if you want to control the switch – your best bet at the moment is eWeLink API or waiting for firmware 3.5 and DIY mode 2.0.

Despite small size and no ESP on the PCB, Sonoff micro comes with the dev pads exposed, so there is a chance that sooner or later someone will come up with a custom firmware.

Sonoff Micro has a secret

I decided to explore eWeLink API in NodeRED further, to create a charge controller. The API allows pulling a detailed description of each registered device with the app. This is where I discovered that Sonoff Micro carries a secret.

Sonoff Micro uses a 4 channel controller firmware. Software-wise, Sonoff Micro can switch 4 relays independently. The actual control of the switch is only via channel 1 (Relay 0) but there are additional 3 channels available. Each one of them works in NodeRED. Why? If you take a look at the USB plug, you will see that the USB 2.0 standard is based on 4 wire interface.

It looks like the initial design of the Sonoff Micro supported data lanes, but during the course of development, the feature was never implemented into the hardware. It’s a shame, but something tells me a 4 channel Sonoff Micro would be more expensive.

Conclusion

Sonoff Micro isn’t going to be a mainstream device. A smart socket has much more to offer, but for the specific use cases, the switch might be just what you need. This product is also a departure from the open-source alike approach to sonoff devices as the gadget is sealed. Despite this, I have one or two projects in mind, and I will be posting about it in my next post (Smart overnight charging). Let me know what are your thoughts about Sonoff Micro in this Reddit thread.