Robot with remote control / Roboter mit Fernbedienung

[rubem]

Hi everyone,

I have this idea for a remotely controlled robot that I want to build. I own two TXTs, two TXT 4.0s and I2C level converters, so I have enough I/O and motor ports. But, as far as I know, the Bluetooth that exists in these controllers cannot be used as a remote receiver. Also the BT Smart Beginner set (I have one) is useless because it can only control two motors and nothing else. So it seems that ft doesn't give you an option to use a remote control for anything beyond very simple models... Is that true? Or is there something I don't know?

Thanks in advance for any response.

Greetings,

Rubem

----------------------- Google Translate

Hallo zusammen,

Ich habe diese Idee für einen ferngesteuerten Roboter, den ich bauen möchte. Ich besitze zwei TXTs, zwei TXT 4.0s und I2C-Pegelwandler, sodass ich genügend E/A- und Motoranschlüsse habe. Aber soweit ich weiß, kann das in diesen Controllern vorhandene Bluetooth nicht als Fernbedienungsempfänger verwendet werden. Auch das BT Smart Beginner-Set (ich habe eines) ist nutzlos, da es nur zwei Motoren und sonst nichts steuern kann. Es scheint also, dass ft Ihnen keine Möglichkeit bietet, eine Fernbedienung für mehr als sehr einfache Modelle zu verwenden ... Stimmt das? Oder gibt es etwas, das ich nicht weiß?

Vielen Dank im Voraus für jede Antwort.

Grüße,

Rubem

[hypnotoad]

With the community firmware for the txt, you can connect the blue remote control with 4 analog channels to it (https://www.fischertechnik.de/de-de/pro ... l-set-blau). Programming would be in Python with ftrobopy. However, the controller is not available any more.

I think I once connected a smartphone with the FT bluetooth app to the TXT, but I did not like controlling without feedback.

It might also be possible to connect a playstation controller via bluetooth, but that requires some more knowledge in Linux bluetooth.

Finally, there is some solution with a Bluetooth-to-USB converter. Afaik it an xbox controller is coupled with that device and it emulates being a joystick to the TXT. However, I forgot the name, but you will find it in the forum.

[Torsten]

Hi Rubem,

the TXT 4.0 as well as the TXT can be connected to the fischertechnik Bluetooth Remote Controller even when using the original fischertechnik firmware (the ftc firmware is not absolutely neccessary).

Unfortunately the Bluetooth RC (which has originally been designed by a company called LNT) only can connect to other bluetooth devices that have a Bluetooth MAC address that has the 3 byte LNT prefix (MoG discovered that already several years ago and shared this information with the community).

The Bluetooth MAC address of the TXT or the TXT 4.0 have to be changed to match this 3 byte LNT prefix. This is possible on both controllers. However it is a bit more tricky on the TXT 4.0 where the new MAC address has to be provided upon boot as a parameter to the Linux Bluetooth module. On the TXT the address can easily be changed any time via command line. On both controllers root access and some Linux knowledge is neccessary to accomplish that, though.

Here is a little video that demonstrates the result on the TXT 4.0: https://m.youtube.com/watch?v=8gVrI1BvSR0

Best,
Torsten

[PHabermehl]

I have used wireless game controllers with USB receiver several times so far. Programming was done in Python.
Gives you less headaches...

[rubem]

Hi Ralf, Torsten, and Peter

Thanks for your quick answers. The conclusion is that fischertechnik indeed does not provide any out-of-the box solution for using TXT / TXT 4.0 controllers as Bluetooth receivers. Sad. They can be controlled by the BT Control Set, although some hacking is necessary and since the controller is not available anymore, this is also not a solution. So, to summarize, what I get so far is that the possible solutions would be:

1) Use another controller (the XBox solution is possibly this one?) to provide communication with the TXT 4.0 using some hacking. I'm not at home with Linux, so maybe this one is not for me.
2) Use an independent solution altogether and connect it to the TXT / TXT4.0 via I²C. Some time ago I already tried one from Arnoud "WhizzBizz" using an inexpensive PS/2 controller and an Arduino Nano. All went well until I tried to solder wires to the PS2 receiver, toasted it, bought another one, toasted the new one again and found out that they die like flies

Of course, any anyone has more ideas, please let me know. @Peter, can you tell a bit more about your solution?

[Edit: Fixed wrong info about Arnoud's PS2 controller project]

Cheers,

Rubem

[werli]

Moin,

Fernbedienung/Fersteuerung per wlan oder BT ist bei den ft-Controllern nicht ganz ohne Risiko!
Bricht die Verbindung ab, bleiben die Ausgänge in dem Zustand, in dem sie sich beim Verbindungsabbruch befunden haben.
Das bedeutet, ein fahrendes Auto fährt weiter und muss händisch gerettet/gebremst werden.
ft-Autos sind zwar in der Regel nicht sehr schnell, wenn aber in 10-15m die BT-Verbindung ausfällt, dann muss man erst mal hinlaufen.

Bei einem Reichweiten-Test mit "Handy und ft-Auto" ist mir genau dieses passiert. Beim ersten Versuch habe ich zu langsam verstanden, was da passiert ist und mein ft-Auto ist bis in die Garage meines Nachbarn gefahren. (Es war ein interessantes Gespräch, als ich meinen Nachbarn bat, sein Auto aus der Garage zu fahren um an mein Auto zu kommen )

Bei einem späteren Versuch, eine automatische Abschaltung zu testen, ist mein ft-Auto von meinem Grundstück auf die Strasse gefahren. Dabei wurde es von meinem Nachbarn mir dem rechten Vorderrad erwischt und geplättet. Die Gespräch dazu war dann nicht mehr so lustig.

Fürs Kopfkino: Ein Kind läuft hinter seinem unkontrollierten ft-Auto hinterher und ......



(Translation with DeepL:)

Moin

Remote control via wifi or BT is not without risk with the ft controllers!
If the connection is lost, the outputs remain in the state they were in when the connection was lost.
This means that a moving car continues to drive and must be rescued/braked manually.
ft cars are generally not very fast, but if the BT connection fails within 10-15 metres, you first have to run to it.

This is exactly what happened to me during a range test with "mobile phone and ft-car". On the first attempt, I was too slow to understand what was happening and my ft-car drove right into my neighbour's garage. (It was an interesting conversation when I asked my neighbour to move his car out of the garage to get to my car )

In a later attempt to test an automatic shut-off, my ft car drove off my property into the street. My neighbour hit it with his right front wheel and flattened it. The conversation wasn't so funny anymore.

For your head cinema: A child runs after his uncontrolled ft-car and ......

[PHabermehl]

@Peter, can you tell a bit more about your solution?

Sorry, I overlooked that ...

I searched for the code but looks like it got lost in time and space.

i used rather cheap gamepads, USB wired and wireless.

Programming was done under Python as said. I can't even remember if i had to install pygame but I used the community firmware anyway.

Basically I can't remember any limitations - analogue and digital signals were read correctly, the button and axes mapping didn't matter much since it could simply be adapted in your own code, so it was pretty straightforward as far as I remember.

I first used this when I had buiilt a fully motorized version of the https://ft-datenbank.de/ft-article/2810 Starlifters Molenbaukran on rails. After being annoyed by a wired control panel based on ft mini switches (they're pretty digital after all...) I used the TXT as interface and the wireless usb gamepad to control the crane.

[rubem]

i used rather cheap gamepads, USB wired and wireless.

Hi Peter,

Thanks for your answer! I think I get it now, you were using a regular PC gamepad plugged to the TXT's USB input and used the community firmware to access the data. So you were able to control your models with Python. Nice! Yes, that could be a solution for me. In the next couple of weeks I'll be on the beach for the holidays, but after that I may give it a try... I have a couple of other ideas too, I'll think about it later on.

Many thanks,

Rubem

[PHabermehl]

Hi Peter,

Thanks for your answer! I think I get it now, you were using a regular PC gamepad plugged to the TXT's USB input and used the community firmware to access the data. So you were able to control your models with Python. Nice! Yes, that could be a solution for me. In the next couple of weeks I'll be on the beach for the holidays, but after that I may give it a try... I have a couple of other ideas too, I'll think about it later on.

Many thanks,

Rubem

Hi Rubem, yes, that's absolutely right. Probably I wasn't clear about that, but you got it anyway.
Well, have nice Holidays! We'll follow up on this topic later, always curious about your findings.

Peter

[rubem]

Hi again,

As a follow-up, I've purchased a cheap ESP32 module that I intend to connect via I²C to the TXT / TXT 4. I had this idea because it would allow me to make a simple module that would avoid the TXT4 Bluetooth altogether. (The ESP32S NodeMcu ESP-12 is the only inexpensive module I found that would fit an ft sound module case. ) As the input I have a very nice Gamesir G8 Mobile Controller attached to my Android phone. With a big hand from my ubiquitous intern ChatGPT I was able to create a simple app in Kotlin / Android Studio that connects to the ESP32 using a simple custom-made Bluetooth protocol. The first tests were sorta okay, but development is a bit painful because these are new environments for me.

I'd prefer to use my son's wireless XBOX controller instead of the Gamesir G8, but this means I'd have to work with the HID protocol which is even more complicated AFAIK. The advantages are that I would be able to avoid Android development altogether and that this is a more reproducible solution -- any Bluetooth controller would do, at least in theory.

Do any of you have any experience with ESP32 and HID? Should I bypass the ESP32 altogether and use the TXT4 Bluetooth? Please share your ideas, I'd like to have some more opinions.

Thanks in advance,

Rubem

[rubem]

Hi everyone,

As a follow-up, and because it seems that the lack of a remote control solution is a hot topic now, I'd like to share the current test setup of my project:

Remote test setup.jpg (1003.01 KiB) 14068 mal betrachtet

After several weekends of trial and error, I was finally able to successfully forward the commands from a Bluetooth gamepad into a TXT 4.0 using a cheap ESP32 module via I²C. I'm still working on it, but the results are encouraging! I can already map any analog input (joysticks, throttle, brake) to the motor speed and the servo position, and use any button to command things like reverse, lamps, etc. Just what I wanted. My Python functions report occasional issues with values outside the allowed ranges and I/O errors, I'll probably be asking for some help soon.

Next step will be to build a case for the ESP32 and an IDC socket, then test the controller with a real model. I'll also be posting the circuit and code for those who wish to make a similar adapter.

Best regards,

Rubem

[rubem]

Hi there,

The remote control is now working. You can see that the ESP32 module and the I2C connector fit exactly inside a 30 mm wide ft case.

Test car.jpg (394.96 KiB) 13521 mal betrachtet

I built this simple test car with the following functions, all controlled remotely:

- RT (throttle): Motor speed
- LB: Headlights and taillights
- RB: Reverse with lights
- Left joystick: Servo steering
- A: Internal horn from the TXT4 (takes a long time to start -- I hope ft fixes this)
- B: External horn using a Sound + Lights Module (it's below the TXT4)

In the future I may create some sort of library in ROBO Pro Coding including slow deacceleration, braking, dead zone, gamepad vibration etc. For now I'm very happy with the results. The gamepad works better than I expected, especially the speed control which is very precise.

Regards,

Rubem

[DrJedi]

Wow Rubem,

thats looks phantastic. I´m a simple doc of engineering so I have no clue about I2C level converter, ESP32, c++.

It´s great that within this community there are experts to show Fischertechnik whats possible. I know, its no rocketscience in 2025 and I´d love to connect my game controller to the every month newly build apparatus of/for my 7yr old son, but this is far above my skills.

The matter is that Fischertechnik electronic is 10 years behind and not even compatible to their own remote controls.
Would be so great they would bring just a game controller and a new controller so that people who are not electronic and software experts can enjoy all the moduls integrated in a modern remote controlled device.

Would be great if you can put a video on YT to present us your lovely car

[rubem]

Hi Markus,

Thanks for your nice compliments. The hardware part is simple enough with just the ESP32 module and an IDC connector. Not even a level converter is necessary because the TXT4's I2C is already at 3.3 V. The PCB has just 4 wires, see below. As for the software part, the ESP32 sketch doesn't do much. It reads the gamepad codes using a third-party HID library and then transfers them to the I2C port. The logic is performed inside Robo Pro Coding.

PCB.jpg (540.93 KiB) 12977 mal betrachtet

But I'd also prefer to avoid hacks altogether and communicate directly to the Bluetooth module inside the TXT4. But I wouldn't know how to do it and even whether this is possible at all, fischertechnik does not always play well with existing standards.

I'll certainly publish a video featuring the car soon. I also want to build something with two independent motors, like a two-wheeled robot or an excavator, and control it via Bluetooth. Lots of ideas now.

Best regards,

[rugee-f]

Hi Rubem, as a startpoint you can try to sniff the serial traffic between TXT4 and RoboPro Coding when you set several outputs in the interface test mode of RoboPro Coding. I did something similar with the RX Controller to figure out the serial protocol commands for the RX to use it as an extension for e.g. RasPi or TXT4. If you know the commands, you can send them via Bluetooth device...

[Arnoud-Whizzbizz]

I have used wireless game controllers with USB receiver several times so far. Programming was done in Python.
Gives you less headaches...

Ich habe keine Erfahrung mit dem Anschluss einer USB-Konsole an den TXT-Controller (ich besitze keine ft-Controller, nur original Silberlingen ) und wie dann die Fernsteuerung gestaltet ist (über BlueTooth an einen zweiten TXT-Controller?) und ob das für dieses Modell notwendig ist, kann ich nicht genau überblicken.

Aber ich habe selbst schon oft mit kabellosen Controllern für Modelle experimentiert. In ft:pedia 2020/4 kann man über meine Experimente mit dem kabellosen PS2-Gamepad lesen, und in ft:pedia 2021/1 über Lösungen via Bluetooth mit einer selbstgebauten Fernbedienung mit einem Arduino Joystick-Shield.

Inzwischen wurde ich von mehreren Leuten gefragt, ob es nicht möglich wäre, ein universelles Modul zu entwerfen, das die Nutzung der kabellosen PS2-Gamepads ohne separaten Arduino erleichtern würde, also z.B. eine Empfängerplatine mit (Motor-)Treiberausgängen, auf die das Empfängermodul aufgesteckt werden könnte und die von einer ft-Batterie gespeist werden könnte.

Daran habe ich auch schon gedacht und es sollte auf jeden Fall möglich sein. Ich bin immer noch neugierig, ob es Interesse daran gibt (und welches „Budget“ die Leute vernünftigerweise für eine solche komplett gebaute Lösung haben, schließlich wird es eine handgefertigte Sonderanfertigung sein)

-----Deepl translation------

With connecting a USB console to the TXT controller I have no experience (I do not own ft controllers, only original Silberlingen ) and how then the remote control is arranged (via BlueTooth to a second TXT controller?) and whether that is necessary for this model I cannot oversee exactly.

But I myself experimented frequently with wireless controllers for models. In ft:pedia 2020/4 you can read my experiments with the wireless PS2 Gamepad, and in ft:pedia 2021/1 solutions via Bluetooth with a self-built remote control with an Arduino Joystick-shield.

I have since been asked by several people whether it would not be possible to design a universal module that would make it easier to use the wireless PS2-Gamepads without a separate Arduino, So for example a receiver board with (motor-)driver outputs on which the receiver module could be plugged in and which could be powered from an ft battery.

I did think about this prematurely and it should certainly be possible. I am still curious if there would be any interest in this (and what 'budget' one would reasonably have for such a completely built solution, after all, it will be custom built by hand)

controller-flitzer2.jpeg (754.63 KiB) 12219 mal betrachtet

[rubem]

Hi Arnoud,

In one of my posts above I already mentioned you, I was able to duplicate your project. It worked well and I even was able to fit the receiver's PCB inside a 60 x 60 enclosure with an Arduino Nano (see photo), but then I was a bit too optimistic... I cut part of the PCB because I wanted it to fit it inside a 30 x 60 housing. I believe the chip couldn't withstand the heat and burned. This happened twice... But I learned a lesson

Failed board.jpg (183.2 KiB) 12028 mal betrachtet

--------------------------------------------------- Google translate

Hallo Arnoud,

In einem meiner obigen Posts habe ich dich bereits erwähnt, ich konnte dein Projekt duplizieren. Es hat gut funktioniert und ich konnte sogar die Platine des Empfängers in ein 60 x 60 großes Gehäuse mit einem Arduino Nano einbauen (siehe Foto), aber dann war ich etwas zu optimistisch... Ich habe einen Teil der Platine ausgeschnitten, weil ich wollte, dass sie in ein 30 x 60 großes Gehäuse passt. Ich glaube, der Chip hat die Hitze nicht ausgehalten und ist verbrannt. Das ist zweimal passiert... Aber ich habe meine Lektion gelernt

Best regards,

Rubem

[rubem]

Hi Rugee,

Hi Rubem, as a startpoint you can try to sniff the serial traffic between TXT4 and RoboPro Coding when you set several outputs in the interface test mode of RoboPro Coding. I did something similar with the RX Controller to figure out the serial protocol commands for the RX to use it as an extension for e.g. RasPi or TXT4. If you know the commands, you can send them via Bluetooth device...

I understand that your suggestion is for me to find out how the USB data is sent to the TXT4. That's interesting, sure, but my goals are more modest. I'm just trying to send remote commands via I2C to a TXT4. I'm not a big fan of Robo Pro Coding (or even Python, for that matter), but I can live with it -- in spite of the awkawardness of the IDE, which is another issue altogether...

Thanks for your input,

Rubem

[rubem]

Hi everyone,

For those who are still following, here is the newest version of the car. The main difference is hardly visible belowe the TXT4. I've replaced the red encoder motor with a 8:1 power motor and now the car is a racer, it can run real fast. I still can set the speed quite precisely, but of course I must be much more careful when handling the throttle control at lower speeds. I also had to extend the overall length a little bit because the power motor requirements, so the Sound + Lights Module is clearly visible now. I've also added a transparent cover to the custom ESP32 module.

rc racer.jpg (146.48 KiB) 9577 mal betrachtet

Best regards,

Rubem

[Arnoud-Whizzbizz]

In one of my posts above I already mentioned you, I was able to duplicate your project.
I believe the chip couldn't withstand the heat and burned. This happened twice... But I learned a lesson

I had not read it carefully yet indeed. In an earlier post you say that you had also blown one and that they “broke down quickly. So also you experience that they apparently get very hot?

I actually did not have this experience at all. That's why I was wondering: did you put the supply voltage of the receiver module at 3(.3) volts? Revisiting the old schematic, I would even think it would be technically more elegant to run the Data/CMD/Ack/CLK lines through a level shifter (5v<-->3v) if you are using a (5 volt) Arduino Uno.

The whole power supply and interfacing becomes easier if you use a 3.3 volt ESP-32 of course.... And so myself, with a supply voltage of 3.3 volts for the receiver, I have not experienced excessive heat generation.

-----translation-----

In der Tat, ich hatte es nicht richtig gelesen. In einem früheren Beitrag sagst du, du hättest auch einen durchgebrannt und dass sie „schnell kaputt gehen“. Du hast also auch die Erfahrung, dass sie sehr heiß werden?

Diese Erfahrung habe ich eigentlich gar nicht. Deshalb habe ich mich gefragt: Hast du die Versorgungsspannung des Empfängermoduls auf 3(.3) Volt gelegt? Wenn ich mir den alten Schaltplan noch einmal anschaue, würde ich sogar denken, dass es technisch eleganter wäre, die Data/CMD/Ack/CLK-Leitungen durch einen Pegelwandler (5v<-->3v) zu führen, wenn man einen (5-Volt-)Arduino Uno verwendet.

Die ganze Stromversorgung und das Interfacing wird einfacher, wenn man einen 3,3-Volt-ESP-32 verwendet natürlich.... Ich selbst habe bei einer Versorgungsspannung von 3,3 Volt für den Empfänger keine übermäßige Wärmeentwicklung festgestellt.