Long before Zigbee, Bluetooth, WiFi and other protocols become a long awaiting standard at our homes, Radiofrequency 433.92MHz was the bandwidth to use to send radio signals from A to B. With an impressive range and next to none latency, and low power consumption (5-40mA), RF433 quickly become a go-to protocol for remote communication. Unfortunately, the dated technology is capped at 9.6kbps, prone to radio interference from other sources and relatively easy to intercept. Is RF going away? Itead Studio thinks not for a while, offering Sonoff RF bridge to add a modern twist to the dated tech.
Sonoff RF bridge
RF433 won’t disappear overnight. Sonoff RF bridge wants to close the gap between smart automation as we know it, and RF signals. The bridge is small and powered by 5V via microUSB. It connects to 2.4GHz band and is able of receiving and sending RF433 signals.
It’s disappointing to see that Sonoff RF bridge natively supports only RF433 signals from its own ecosystem and there is no access to raw RF data.
Up until now, you could only use Sonoff RF remote with RF433 enabled sonoff devices. Sonoff RF changes this, allowing you to store up to 16 signals in its memory. Here are Sonoff devices that are RF compatible:
You will be able to link it to any device in your eWeLink ecosystem.
Setup
The pairing process was simple. Select quick pairing, make sure you are connected to 2.4GHz bandwidth and your Sonoff RF bridge will pop to the list of eWeLink devices after a minute.
Sonoff RF bridge is another device that refuses to update the firmware without trickery. It happened to me before with Sonoff R3 Basic where I had to create an AP on my mobile to force the update through 🤷♂️.
Remote Paring
I got the Sonoff 4 button remote a while back, so I wanted to pair it. The procedure is simple and easy to follow. I paired my remote on my first try. Add the device type from your list, then press each button on the interface to set it into pairing mode. Tap a corresponding button on the Sonoff RF remote and you are good to go.
Sonoff RF bridge in use
Sonoff RF bridge works in 2 modes. It acts as a hub between RF433 sensors (PIR, door sensor) and uses these as triggers for eWeLink app scenes, or you can pair the Sonoff RF remote, and have the bridge send the same RF signals as you would with your remote.
Come to think of this, Sonoff RF tries to fill a very niche use. It’s not something I really need in my setup, and with Zigbee becoming cheaper and simply better, RF433 becomes more redundant.
Inside we have
I had a cheeky look inside to see what the Sonoff RF bridge is made of. It is an ESP8285 based module with RF433 chip.
It’s nice to see properly exposed pins. There are 4 sets of GPIO pins:
- Serial (Vcc, RT, TX, GND)
- SPI(?) (Vcc, C2CK, C2D, GND)
- GPIO (Vcc, GPIO 04, GPIO05, GND)
- Serial (SDA, TC, RX, Vcc, GND)
- ON/OFF toggle (flash)
Two more pins are exposed at the bottom of the PCB: GPIO12 and GPIO14.
Conclusion
Sonoff RF bridge isn’t expensive (around $15) but feels somehow limited. Adding Tasmota to the mix would enable other RF devices, but due to hardware limitations, you would be still limited to 16 RF inputs. Reading Tasmota documents, it’s possible to get the raw data from the RF signal, but considering Zigbee alternatives, I’m inclined not to explore this further (for now). I only have Sonoff RF devices at home (mostly for testing purposes) so I’m lacking the drive to explore this further. What do you think my dear reader? Let me know in the Reddit thread.
