A care package from Sonoff arrived just before Xmas. Apart from the usual swag, wrapped inside a sock was a new Sonoff device. After significant re-design moves with the Sonoff Elite series, I’m pleased that the same treatment is given to their relays. Sonoff MiniR4 looks excellent but it’s also tiny. Want to know more?
Sonoff Mini evolution
Over time, the Sonoff Mini changed quite a bit. A smaller really designed to work behind light switches was first released as a WiFi device, and later as a ZigBee-connected module. In both cases, the footprint was the same. Sonoff MiniR4 is MUCH smaller – meet the extreme edition of the Sonoff Mini series.
How small is it?
It’s tiny! It’s the smallest relay I had in my hands to date. There is only one smaller relay I’m aware of – Evvr Switch – but only because it uses 2 devices to control your lights. Sonoff MiniR4 is smaller than Shelly Plus 1 or the equivalent from Aqara. In other words – if you were tight for space behind your switch, Sonoff MiniR4 is your best bet.
At 40x33x17mm, it has everything a switch like this needs. It’s a single-channel relay that uses 2.4GHz WiFi to connect to your network. Just like other Sonoff Mini switches, it comes with support for 2/3-way switching and requires live and neutral to be connected to your circuit. Folks in the USA will be happy about it, anyone else like me, will have to put it behind the ceiling rose to get the necessary power.
Terminals are solid (screw-in clamps) but on the small side, if you have any wires that need bridging you will need Wago connectors. Thankfully, Sonoff MiniR4 has enough terminals to cover a typical use case.
Inside Sonoff MiniR4
As usual, I decided to open it up and poke around before I connect it to power. To no surprise, Sonoff MiniR4 uses ESP32- D0WD V3 to connect to WiFi and supply Bluetooth to complete the pairing process. The IC is tightly packed on a daughter board and while exposed, it’s going to be hard to actually flash it.
The same goes for the relay. It’s connected to the main PCB via the daughter board and the relay has no markings on it. Sonoff instructions specify the max current of 10A (resistive load) which is more than enough for most lights installations.
There are no proper headers but dev pads for RX, TX, GND RST and KEY are available to anyone with a steady hand. I’m sure it’s flashable – the question is how hard is going to be to solder tiny wires? I will cover flashing it in a dedicated article.
Another significant change is the antenna. Other Sonoff Mini modules have an external antenna that you could glue to a side of the switch for a better signal, Sonoff MiniR4 comes with a 3D antenna which should provide improvements over an embedded PCB one. I have a mesh router at home, so my signal is pretty strong throughout the house but covering the relay with a metal bracket did not impact its performance. Your mileage may vary.
Pairing and wiring
It’s a single-channel relay with switch support. The wiring is very easy thanks to the correct number of terminals provided. Each one is clearly labelled so the risk of doing something unfortunate – like blowing up Sonoff Dual, for example, is low.
There are 2 in-wall switch terminals that allow for single or two-way operation. It’s exactly the same system that is present on other Sonoff Mini devices. It will be down to you to pick your switch wiring.
As Sonoff MiniR4 is ESP32 based, the pairing happens over Bluetooth and it’s quick and painless. The device shows up in eWeLink as a single-channel relay and this is the first time I see the option to assign the icon to the card (sorry eWeLink it’s been a while).
I connected it to my bench setup, and there were no surprises there. Sonoff MiniR4 worked well, there was almost no latency between app controls, in-wall switch triggers and updates from the switch to the eWeLink cloud. Connected, Sonofff MiniR4 draws about 0.5W of power, which is pretty typical for all WiFi relays with the usage spiking to 0.8W when in use.
Is anything new in the app?
It’s a WiFi relay, so it works over a 2.4GHz network. eWeLink exposes 3 ways of connecting your physical switch: pulse mode (push button), edge mode (typical toggle) and following mode (latching switch) so all your main switch types are covered. There is an option to detach the relay, in which you can simply repurpose your wall switch to other actions while retaining network control of your light. You’ll see switch options available in the Automation panel as a trigger.
Another unique to Sonoff MiniR4 feature is support for eWeLink Remote protocol, as well as Local LAN controls. It means that if you have an eWeLink Remote device, you can link it to your Sonoff MiniR4 and use it together without needing a hub, cloud or internet connection.
Apart from that, the above, the standard features are also available – anyone looking for inching (up to 24h), power state recovery (with additional delay) or device-specific push notifications, will find the options in the app settings. Timers, schedules and Alexa/Google Home controls are also included in the eWeLink so it’s plain sailing setting this up with your voice assistant of choice.
Sadly, I don’t have any information about Sonoff DIY 2.0 support. Given the previous history of Sonoff Mini devices, it’s unlikely to happen even if I personally think developing this mode would be very beneficial to Itead.
When and where?
There is one problem. Itead was happy for me to share my 1st impressions and see the initial feedback from all of you guys, but Sonoff MiniR4 isn’t available for sale just yet. Itead contact mentioned that the relay should hit the Itead Store in the first quarter of 2023. If you want to get an email notification from ITEAD use this link. As the biggest advantage of the Sonoff MiniR4 is the size, anyone with enough space behind the wall socket should take advantage of the fact that the Sonoff MiniR2 (which offers the same functionality) will be available at a discounted price until stock lasts. It’s an excellent opportunity to save a couple of dollars while we all wait for the latest tech.
I know what is on everyone’s mind. Tasmota. All in due course and I promise to post a guide soon (as soon as I’m done testing things on my end). If you want to find out how flashable Sonoff MiniR4 is, and if not having eWeLink will be an option for you – then stay in touch. As usual, leave me your thoughts in this Reddit thread.
🆓📈 – See the transparency note for details.