If you watched the livestream, you knew this one was coming. Apart from Sonoff Zigbee Bridge, ITEAD has one more product, which will be released in a couple of weeks. Frankly speaking, I’m not sure what to think of it. This is Sonoff WiFi Contact sensor (DW2-WiFi).
WiFi? I’m actually surprised. If I didn’t know about the Zigbee sensors in the pipeline, perhaps the Sonoff WiFi Contact sensor would make more sense. I do know that Zigbee sensors are on the way, so having a WiFi-based equivalent leaves me scratching my head. Do they have too many ESPs laying around or…?
When you fail at first…
That livestream was not my proudest moment. I failed at pairing this thing. In my defence, I had no instructions or the idea what’s inside the Sonoff WiFi contact sensor and how I should pair it. I was tipped after the livestream that the sensor uses Bluetooth to pair. eWeLink app has the option for it too – but you have to scroll through 4 others to see it.
The cat is out of the bag at this point. This thing has Bluetooth as well as WiFi – I don’t think ITEAD is crazy enough to use ES32 to power such a simple device so I was very eager to look inside.
Is it just me, or does it look like an Amazon Button to you? I think the LED and the logo bring that impression. It’s definitely similar in size. I actually converted one Amazon Dash button into a security sensor before! Having one to one comparison made me smile.
Sonoff WiFi contact in use
Due to how responsive the Sonoff WiFi Contact is, I have no doubts, this thing is actually connected all the time. It’s too responsive to detect magnet, wake up processor, fire up WiFi radio, connect and authorise the credentials and push the info to cloud in less than a fraction of the second.
Powered by 2 AAA batteries, picture promises up to 3 months of battery use. I’m not able to tell you if that’s true, but the sensor comes with battery monitoring, which is displayed in the app.
There is one advantage of having a constantly connected sensor would be the ability to query it at any time. Unlike with RF433 or even Zigbee devices, the information about the sensor status is sent on the trigger (contact, or battery level).
Inside Sonoff WiFi Contact sensor
Due to poor light conditions, I actually misidentified the chip on the livestream. This is OPL1000-A2 based device. The chip supports Bluetooth and WiFI.
- Wi-Fi 11b up to 11Mbps
- BT 5.0LE + 2Mbps data rate
- Outstanding RF performance
- Ultra-low power
- Dual ARM Cortex M0 / M3
- Extensive peripherals
- Integrated PMU
- Complete hardware security crypto engine
- DC analogue inputs
What’s even more interesting – there is an SDK firmware available and serial pads ready to play with this thing. Sonoff WiFi Contact is going to be hacked the moment it hits the online shelves.
The sensor promises 3 months of battery life. It’s WiFi, so I checked the current consumption. Looks like the OPL1000 uses about 20mA to initiate, about 10mA to send the open/close info over the WiFi and 0.3mA in the stanby.
I probed the TX RX with Pokit Meter (review) in the oscilloscope mode and it looks like the device is transmitting in the standby mode as well. Pinging Sonoff WiFi contact reveals that the device remains connected, although the packet loss exceeded 50%. Does it mean I would be able to query the sensor as well? It’s too soon to tell, but it’s an interesting architecture.
Sonoff WiFi Contact is available for preorder at $6.99 via ITEAD Store. Question is: how much Sonoff WiFi Contact is going to clash with their Zigbee release? Zigbee products are fantastic in terms of size and battery use, and this sensor will have a hard time beating it! Unless the price will be halfway between RF433 sensors and Zigbee. What do you think? Let me know in this Reddit thread.