This project supports the both versions of the Sonoff RF Bridge via the firmware file sonoff_bridge-firmware.bin.
You must solder header pins onto the circuit board to access the UART/Serial interface. The J2 holes conveniently have the pin names printed on the circuit board. You can solder in right angle header pins so that you can place the circuit board back into the casing. Only 4 header pins are required: the 3V3, RX, TX and GND.
It is easier to solder the header pins after you have done any hardware modifications.
Having the header pins soldered in allows you to flash another firmware later on. This device does not support OTA, flashing via serial or the Config Portal.
To put the device into flashing mode, the pairing button must be held down whilst inserting the UART dongle into the USB on your computer. Finding a proper time to release the pairing button could be tricky. The button should be release after esptool is executed and just before Connecting... apears.
If your UART dongle cannot supply the required power then disconnect the 3.3v pin on UART (while keeping the RX, TX and GND pins connected) and then plug the device in via the built in USB port (marked as J1 on the board) to power it via an appropriate USB power adapter that can provide 1 amp.
DO NOT CONNECT BOTH THE J2 3.3V PIN AND J1 AT THE SAME TIME AS YOU MAY DAMAGE YOUR BOARD.
After each step below, you will need to disconnect and reconnect your UART device (or if powering the board via J1 - connect and disconnect this instead).
If you have not yet installed the 'esptool' module for python:
python -m pip install esptoolCreate a backup of the Sonoff firmware:
python -m esptool --baud 460800 read_flash 0x00000 0x100000 Backup_SonoffRFBridge.binErase firmware:
python -m esptool --baud 460800 erase_flashFlash the RFLink firmware:
python -m esptool --baud 460800 write_flash -fs 1MB -fm dout 0x0 sonoff_bridge-firmware.binYou can then use either the CLI connected via the UART to configure the RF bridge or the Config Portal.
To use the Config Portal, connect to the RFLink-AP access point and navigate to http://192.168.4.1 in your web browser. Use rflink32 for username and 433mhz for password.
To use this firmware a few hardware modifications must be carried on the gateway circuit board known as the Direct Hack to work correctly.
The circuit board will have the revision and version printed on it, ensure you follow the correct instructions.
Credit goes to mateine from the HomeAssistant forum.
This modification bypasses the signal decoder on the Sonoff board so that the ESP8285 is connected directly to the RF chip. The soldering skill required is between low to medium difficulty.
Four circuit traces must be severed and two separate lines must be soldered together via resistors to complete the modification. Any resistor in the range of 180Ω to 680Ω can be used. You can sever the traces with a sharp blade or craft knife.
Using the resistors will prevent any damage to the semiconductors in the case where a short circuit occurs.
Like in the image above, cut the three traces. The two traces grouped together connect the USB data with the GPIOs. The trace above them connects the transcoder chip to the RF transceiver.
Cut the trace and then solder the two resistors to their appropriate points on the circuit board.
Connect the USBRXD to pin 5 of the U4 chip near the LEDs for the receiver.
Connect the USBTXD to pin 4 of the U5 chip near the button for the transmitter.
It is recommended that you shape your to avoid surface mount components, like pictured above.