HowTo: Tasmota – Sonoff RF Bridge RF chip (EFM8BB1) flashing with Portisch firmware

Thanks to the very universal Tasmota firmware (see: flashing Sonoff 433Mhz Rf Bridge with Tasmota firmware), you can use the Sonoff RF Bridge to send and receive just about any 433Mhz signal. However, this works only for 433Mhz signals whose radio protocol is detected by the firmware of the EFM8BB1 processor. That means you receive – with the standard firmware – only radio data already interpreted by the EFM8BB1 processor. Thanks to a firmware update, you have the option to read out any wireless raw data.

Which modifications you have to make and what you have to pay attention to is described in this article.

Hints for our lovely english readers: Basically, many of the articles on are translations from the original german articles. Therefore, it may happen here and there that some illustrations are not available in english and that some translations are weird/strange/full of mistakes or generally totaly wrong. So if you find some obvious (or also not obvious) mistakes don't hesitate to leave us a hint about that in the comment section. 
Also please don't get confused, that instead of a "dot" often a "comma" is used as decimal separator. 🙂

Safety instructions

I know the following hints are always a bit annoying and seem unnecessary. But unfortunately, many people who knew it "better" from carelessness lost their eyes, fingers or other things or hurt themselves. In comparison, a loss of data is almost not worth mentioning, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Even the coolest project is worth no injury or other annoyance.

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Helpful Articles:
Before you start building, you should have dealt with the soldering basics. You have to solder wires to contacts. In addition, you should have already flashed your Sonoff RF Bridge with the Tasmota firmware.
The following articles contain information about this:
Electronics – My friend the soldering iron
Sonoff – 433Mhz RF Bridge flashing Tasmota firmware
Basics of navigation in Windows Explorer

Required tools:

In the following list you will find all the tools you need to implement this article.

Required material:

In the following list you will find all the parts you need to implement this article.

Disconnecting unneeded data lines

The data lines of the EFM8BB1 (RF chip) that you need to connect during this mod with the ESP8266, are standard connected to the data lines of the micro USB port that normally powers the RF bridge.

Probably the manufacturer has a special adapter which allows him to program the EFM8BB1 in this way – for us this function is useless and in this case even a barrier on our way of flashing the EFM8BB1. In conclusion this means that you can not power the RF bridge via the micro USB port at the same time and program the EFM8BB1.

To make this possible anyway, this section explains how to cut through the connections from the EFM8BB1 to the micro USB port.

Take the board of the RF-Bridge – like for the original flash process of the ESP8266 – out of the case …
… and turn it over.
Now you need a cutter knife (or another sharp knife – a scalpel is also very good) …
… and cut through the two data line as seen in the photo.
Close-up of disconnected data lines.

Connecting the data lines of the EFM8BB1 to the ESP8266

In order to connect the needed GPIOs of the ESP8266 with the data lines of the EFM8BB1, you first have to prepare two cables about 3 cm long.

Insulate the ends and tin them with some solder.
These are then used as shown to connect the mapped contacts.
Close-up of the connection between the EFM8BB1 data line and the ESP8266 contacts.

Before starting up, you should now follow the tips from the article Electronics – Commissioning a new circuit.

Preparing the Tasmota firmware

For the Tasmota firmware to be able to flash the EFM8BB1, you need to enable the following option in the Tasmota firmware.

Open the Tasmota firmware in the Arduino IDE and scroll in the tab “user_config.h” to the marked line.
There you remove the “//” before the “#define USE_RF_FLASH” and activate the desired function. Then you have to reprogram your RF-Bridge with the changed settings. How to do this is described in the article Sonoff – 433Mhz RF Bridge flashing with Tasmota firmware.

Upload the new firmware to the EFM8BB1

With the modified hardware you can now easily change the firmware of the EFM8BB1 from the usual Tasmota configuration page of the RF-Bridge.

It is important that you have the GPIO pins 4 and 5 set to “00 None” under “Settings” and “Configure Device”. This is usually the default. So if you have not consciously misguided, you do not have to worry about it. The GPIO pins 4 and 5 must not be used because these are used by the Tasmota firmware to program the EFM8BB1.
To start uploading firmware to the EFM8BB1, go to Firmware Setup from the main Tasmota configuration page.
There you click on “Durchsuchen”(German for “Browse”) …
… and select via the Explorer as usual the firmware to be flashed. These can be found in the folder that also contains the Tasmota firmware. Go to the folder “Tools” …
… then “fw_efm8bb1” …
… and select the latest firmware files available there.
After clicking on “Open” you return to the configuration page. There you click on “Start upgrade”.
The upload takes about 30 seconds …
… and is confirmed with an “Upload successful” message.

The new firmware then behaves first like the old firmware. The difference is that the new firmware can also be switched to a raw mode.

What this is all about and how to use it will be explained in another article.

I hope everything worked as described. If not or you have any other questions or suggestions, please let me know in the comments. Also, ideas for new projects are always welcome. 🙂


P.S. Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you appreciate it that I share these information with you, I would be happy about a small donation to the coffee box. 🙂

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  1. Hi,
    gibt es den Nachfolgeartikel schon?
    Ich habe ein paar Funksteckdosen, die sich nicht mit der Standardfirmware anlernen lassen und deshalb die Portisch-Software geladen.
    Im Sniffermodus (RfRaw 177) sehe ich u.a. folgendes JSON:
    {“RfRaw”:{“Data”:”AA B1 04 02EE 01F4 0582 2016 381A1A1A1A0A1A0A0A0A0A0A0A0A280A280A0A0A0A 55″}}:
    Wenn ich das mit BitBucket Converter konvertiere, bekomme ich:
    AA B0 1F 04 08 02EE 01F4 0582 2016 381A1A1A1A0A1A0A0A0A0A0A0A0A280A280A0A0A0A 55
    Ich habe versucht das mit:
    …/Backlog = RfRaw AAB01F040802EE01F405822016381A1A1A1A0A1A0A0A0A0A0A0A0A280A280A0A0A0A55; RfRaw 0
    an die Bridge zu schicken, aber leider reagiert die Steckdose nicht.
    Was mach ich falsch?

    1. Hey Peter,
      den Entsprechenden Artikel gibt es leider noch nicht. Ist aber auf meiner Liste. 🙂 Welchen Code hast du denn dort gesniffed? Den vom Einschalten oder Ausschalten der Steckdose? Soweit ich weiß unterscheiden sich die beiden. 🙂
      Beste Grüße

  2. Hallo Fab,
    prima Anleitung, Danke dafür.
    Jetzt bin ich aber in derselben / ähnlichen Situation wie Peter im September 2020.
    Ich bin gespannt auf die angekündigte Anleitung …. 😉

    Danke & Gruß Siggi

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