Looking at the latest Sonoff ZigBee bridge, you couldn’t distinguish between the one released now: Sonoff ZB Bridge Pro and the one I covered a couple of years ago and flashed tasmota on. The identical, white shell carries new hardware. Should you even care? What’s so pro about it?
Edit 27/05/2022: now flashed with Tasmota!
Sonoff ZigBee Bridge Pro
Identical on the outside to the fault. It’s been 2 years, and Sonoff still hesitates to put USB-C ports in their devices. Sonoff ZigBee Bridge Pro comes with a reset pinhole, the micro USB port to power it on, and probably the shortest USB lead known to man. I’m not kidding, it’s barely longer than the Sonoff ZigBee Bridge Pro.
It’s not the most exciting unboxing, or a tour of the device so let’s poke inside and check the PCBs out before we fire this baby out and compare it to the previous model. The biggest change this time around was the jump from EFR32 ZigBee IC to more familiar to us tinkerers CC2652 series IC from Texas Instruments featured on other coordinators like ZZH by Electrolama or ZigStar and the Sonoff USB dongle.
To handle the Internet, Sonoff ZigBee Bridge Pro uses ESP32-DOWD v3 with support for Bluetooth (that’s how the device pairs) and a 2.4GHz network. What’s completely new is the addition of the cell battery and Espressiff branded PSRAM. The battery cell keeps the RTC clock operational, so in the event of power failure, time-based settings stored on Sonoff ZigBee Bridge Pro can execute even if the access to the internet is limited. That’s a handy feature to have on ZigBee networks.
I appreciate the support for 128 subdevices (jump from 32 devices on the original Zigbee Bridge) thanks to the new coordinator, but the lack of 5GHz WiFi and the option to use Ethernet to connect to your network doesn’t scream PRO to me. Initially, I thought that the limit of 128 sub-devices applies to end devices only, but after confirming with the Sonoff rep, the direct support is limited to 26 devices directly and up to 128 devices via the developed ZigBee mesh (you will need routers to reach this device limit).
Thankfully, on both sides of the PCB, dev pads are exposed and we have the access to programming interface for ESP32 and CC2652. I have no doubt that the flashing guide will follow soon, especially since Sonoff ZigBee Bridge Pro is vividly discussed on GitHub already. Exposed pads include:
- GND, 3.3, RX, TX, GPIO00
- SDA, SCL, M_TCK, CHIP_UP
- DIO14, DIO11, Z_TMS, Z_TCK Z_IO8
- 5V, RST, GND, 3V3, BZ, LED_G, KEY
Using Sonoff ZigBee Bridge Pro
As my unit isn’t flashed, let’s see what eWeLink has in store for us. Thanks to the ESP32 inside the pairing happens via Bluetooth and it’s relatively quick and trouble-free. It takes less than a minute and your Sonoff ZigBee Bridge Pro is ready to be used.
The first thing was to update the firmware, as an update is already waiting for me. Then I was free to use new options in the eWeLink Hub.
Apart from visual changes in the device cards (this probably came before the release, but it’s been a while since I fired up a stock bridge), the biggest change is the introduction of the security suite inside the bridge. Just like Aqara and Xiaomi ecosystems their bridges allow you to manage home security with a single press of a button. Sonoff ZigBee Bridge Pro brings similar options to the main menu. By default they are called: Home/Away/Sleep but in the settings, you will find an option to rename these.
If you have never used anything like this before, the Alarm suite enables you to select and assign an array of sensors which will be activated with a button press. When the alarm mode is armed, all sensors signed to that group will report back and sound an alarm when triggered. The alarm will issue a push notification as well as a 10-sec beep from the Sonoff ZigBee Bridge Pro itself.
Only Sonoff Switch (SNZB-01), Motion Sensor (SNZB-03) and Contact Sensor (SNZB-04) can be assigned to alarm profiles. It’s a shame that the Temperature & Humidity Sensor (SNZB-02) isn’t allowed as it would enable users to create temperature based alarms. It’s not a massive problem, these alarms can be set via Automation Scenes.
CC2652 inside the Sonoff ZigBee Bridge Pro offers a stronger signal as well, but when it comes to an effective range in the mesh ecosystem, relaying on the coordinator alone without building up your mesh, isn’t the best bet. The effective range will also depend on both devices. Increasing the signal strength of the coordinator doesn’t translate into a longer range using the same devices.
The argument could be made for a stronger signal within the mesh itself, but unlike WiFi, the ZigBee signal doesn’t benefit from the same boost. Signal strength in WiFi influences the speed of the data transfer. As ZigBee protocol isn’t as data-intensive, getting a couple of dB won’t change how effective your network is in all but the most extreme circumstances.
Knowing all this, I still took the Sonoff Switch (SNZB-01) for a walk around the house, visiting familiar dead spots, and comparing the results to the previous-gen bridge. Without other routers, the range of the coordinator covered a 2-floor house with a button being clickable on the outside of the house as well up to around 3-4m.
EFR32 based Sonoff Zigbee Bridge had actually a longer range with the older ZigBee Bridge covering the entire garden and adding extra 5-7m to the range. As I was surprised by this result, I run the test several times, pairing the button back and forth to verify it wasn’t just some interference. The older Sonoff Bridge has a much better range, but the Sonoff ZigBee Bridge Pro should cover your entire house even if your mesh isn’t well developed. In both cases, sensors were fast and responsive, so no complaints from me there.
Other than everything above, Sonoff ZigBee Bridge Pro is just a regular ZigBee hub with an addition of the buzzer and RTC inside. You can still link other ZigBee based relays from the Sonoff ecosystem and set up automation scenes in the eWeLink up, but I had no luck with 3rd party sensors and buttons from Aqara, Tuya or IKEA. Tuya ZigBee hubs are more flexible in this regard.
Well know what will happen next, the community is already working on ways to add custom firmware to the coordinator and the ESP32 to enable Tasmota and Zigbee on Sonoff ZigBee Bridge Pro. I’ll be paying attention to that development. At the moment $24.90 isn’t a terrible price to pay for a ZigBee hub, and if you hit the 32 sub-devices limit and you can’t think of other routers/coordinators that you can add to your ZigBee mesh, getting Sonoff ZigBee Bridge Pro might be just the upgrade that you need. Let me know what you think in this Reddit thread.
🆓📈 – See the transparency note for details.