HowTo: Tasmota – Flash Sonoff RF Bridge RF-Chip(EFM8BB1) with Portisch firmware

Thanks to the very universal Tasmota firmware (Flash Sonoff 433Mhz Rf Bridge with Tasmota firmware) you can send and receive pretty much any 433Mhz signal using the Sonoff RF Bridge. However, this only works for 433Mhz signals whose radio protocol is recognized by the firmware of the EFM8BB1 processor. This means that with the standard firmware you will only receive radio data that has already been interpreted by the EFM8BB1 processor. Thanks to a firmware update, however, you have the option of reading out the raw radio data.

What modifications you need to make and what you need to pay attention to are described in this article.

Safety instructions

I know the following notes are always kind of annoying and seem unnecessary. Unfortunately, many people who knew "better" have lost eyes, fingers or other things due to carelessness or injured themselves. Data loss is almost negligible in comparison, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Because even the coolest project is not worth injury or other trouble.

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Helpful articles:
Before you start construction, you should have dealt with the basics of soldering. You have to solder cables to contacts. You should also 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 with Tasmota firmware flashing
Basics of navigating in Windows Explorer

Required material:

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

Required tool:

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

Cutting the data lines that are not required

The data lines of the EFM8BB1 (RF chip), which you have to connect to the ESP8266 with this mod, are by default connected to the data lines of the micro USB port through which the RF bridge is normally supplied with power.

The manufacturer probably has a special adapter that allows you to program the EFM8BB1 in this way - but for us this function is useless and in this case even a hindrance. This means that you cannot supply the RF bridge with power via the micro USB port and program the EFM8BB1 at the same time.

In order to make this possible, the connections from the EFM8BB1 to the micro USB port will be severed in this section.

Take the RF bridge board out of the housing – as you did during the original flashing process of the ESP8266…
...and turns it over.
Now you need a cutter knife (or other sharp knife - a scalpel is also very suitable)…
...and cut so that the two data lines can be seen as shown in the photo.
Close-up of the severed data lines.

Connecting the data line of the EFM8BB1 to the ESP8266

In order to connect the contacts of the ESp8266 to the data lines of the EFM8BB1, you first have to prepare two lines that are approximately three cm long.

To do this, strip the ends and tin them with a little solder.
These are then used as shown to connect the contacts shown.
Close-up of the connection between the data line of the EFM8BB1 and the contacts of the ESP8266.

Before commissioning, you should now follow the tips from the article Eektronik - Commissioning of a new circuit note.

 Tasmota firmware preparation

In order for the Tasmota firmware to be able to flash the EFM8BB1, you must activate the following option in the Tasmota firmware.

To do this, open the Tasmota firmware in the Arduino IDE and scroll in the “user_config.h” tab to the marked line.
There you remove the “//” in front of the “#define USE_RF_FLASH” and thus activate the desired function. You then have to program your RF bridge again with the changed settings. How to do this is in the article Sonoff – Flash 433Mhz RF Bridge with Tasmota Firmware described.

Installing the new firmware on 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 GPIO pins 4 and 5 set to “00 None” under “Settings” and “Configure device”. This is also usually the default setting. So if you didn't consciously change anything, you don't have to worry about it. GPIO pins 4 and 5 must not be used because they are used by the Tasmota firmware to program the EFM8BB1.
To then start installing the firmware on the EFM8BB1, go to “Firmware Upgrade” from the main menu of the Tasmota configuration page.
Then click on “Browse”...
...and select the firmware to be flashed using Explorer as usual. You can find this in the folder that also contains the Tasmota firmware. To do this, go to the “Tools” folder…
…then “fw_efm8bb1″…
...and select the latest available firmware files there.
After clicking on “Open” you will return to the configuration page. There you then click on “Start upgrade”.
The upload then takes approx. 30 seconds…
...and is confirmed with an “upload successful” message.

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

I will explain what it is all about and how to use it in another article.

Have fun with the project

I hope everything worked as described for you. If not or you have questions or suggestions please let me know in the comments. I will then add this to the article if necessary.
Ideas for new projects are always welcome. 🙂

PS 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 think it's cool that I share the information with you, I would be happy about a small donation to the coffee fund. 🙂

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  1. Hi,
    is the follow-up article already available?
    I have a couple of radio-controlled sockets that cannot be taught with the standard firmware and therefore loaded the Portisch software.
    In the sniffer mode (RfRaw 177) I see the following JSON:
    {“RfRaw”:{“Data”:”AA B1 04 02EE 01F4 0582 2016 381A1A1A1A0A1A0A0A0A0A0A0A0A280A280A0A0A0A 55″}}:
    When I convert this with BitBucket Converter I get:
    AA B0 1F 04 08 02EE 01F4 0582 2016 381A1A1A1A0A1A0A0A0A0A0A0A0A280A280A0A0A0A 55
    I tried this with:
    …/Backlog = RfRaw AAB01F040802EE01F405822016381A1A1A1A0A1A0A0A0A0A0A0A0A280A280A0A0A0A55; RfRaw 0
    to the bridge, but unfortunately the socket does not respond.
    What am I doing wrong?

    1. hey peter,
      Unfortunately, the corresponding article does not yet exist. But it's on my list. 🙂 What code did you sniff there? The one from turning the socket on or off? As far as I know, the two are different. 🙂
      Best regards

  2. Hello Fab,
    great guide, thanks for that.
    But now I am in the same/similar situation as Peter in September 2020.
    I'm looking forward to the announced instructions .... 😉

    Thank you & greetings Siggi

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