Old two-wire ultrasonic distance sensor with TXT? / Alter Zweidraht-Ultraschall-Abstandssensor mit TXT?

[rubem]

Has anyone attempted to connect the old two-wire ultrasonic distance sensor 128597 to a TXT? I've searched the forum but didn't find any specific information about this.

Hacks and soldering are very welcome

Thanks a lot for any information!

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Hat jemand versucht, den alten Zweidraht-Ultraschall-Dinstanzsensor 128597 an ein TXT anzuschließen? Ich habe das Forum durchsucht, aber keine spezifischen Informationen dazu gefunden.

Hacks und Löten sind sehr willkommen

Vielen Dank für jede Information!

[vleeuwen]

That is not possible.
The 2 wire protocol is complet different from the 3 wire protocol.

[rubem]

@vleeuwen, I understand that the sensor cannot be connected directly, thank you for the confirmation. However I see the circuit board has four unused pins (bottom left) which may be useful for hacking. There are also four interesting pads right above the bottom IC. Maybe the pins are compatible with an HC-SR04, I don't know. I would not be afraid to check out these pins if only I was sure where the 9V goes. The board has three "+" marks, which don't tell me much... See below:

usboard.jpg (141.57 KiB) 7839 mal betrachtet

[Bjoern]

Hi Rubem,

do you have the old Robo Interface? If yes use a scope to check the communication of the wireing. One is GND and the other is the data.

I´m pretty sure that you find a way to connect it at the end. Maybe with a hack...

Björn

[rubem]

Hi Bjoern, I don't have the Robo interface, unfortunately. The power must have been supplied over the data signal (red wire) somehow. Documentation shows that the Robo interface had some sockets for it, I believe they were called D1 and D2. But this is something the TXT doesn't have. So much for backwards compatibility...

Oh, and thanks for your optimism but I'm not so sure I can hack it. It would be much easier if somebody had a schematic. (It's a discontinued product, so I believe our friends at ft wouldn't mind.)

[vleeuwen]

Yes, the D1 and D2 are switching between their role as power supply and as information receiver.
Richard Budding has done some developing work in that area:
See the FTc web site, "search Budding" or "Ultraschall-Entfernungsmesser R. Budding "
https://ftcommunity.de/bilderpool/baste ... ngsmesser/

[H.A.R.R.Y.]

Hello,

the issue with R. Budding's project is simply: He did his own electronics using a different interface. His project does not reveal things about the old US sensor.

All we could assume about the 128597 and its 2-wire interface is that the voltage supplied by the interface might be modulated to trigger a measurement. Or is it simply the appearance of the supply voltage that triggers it? After a while the current draw is modulated and conveyes the distance coding. Or is it just a peak or drop in the current draw that denotes when an echo arrives? But even if the schematic is known, most of the "magic" is handled by the on-board microcontroller. For a full reengineering one at least needs to have the old sensor, the old interface and enough experience in electronics including the equipment necessary.

The topic is not new but still there is no known solution. Just questions you might find when searching through our forum: search.php?keywords=128597

Regards
H.A.R.R.Y.

[vleeuwen]

The lifespan was also not that great, soon after that came the TX-C and the three wire distance sensor.
I think you could see quite a bit with an oscilloscope
You could contact Knobloch, they designed and built the ROBO interface and the software.
https://knobloch-gmbh.de/

[rubem]

Hi,

Vleeuwen and H.A.R.R.Y., thanks a lot for the useful info! It seems that R. Budding used a standard ultrasonic sensor (HC-SR04 or similar) and added a custom PCB to it so that it would send information to the Robo interface somehow. It's a great idea and I had plans to use an Arduino Pro Mini for something similar. However in the meantime I was lucky to find a bunch of used ft parts which I purchased for a very good price. When the lot arrived this week I realized the sensor was not the 133009, but the older 128597 which I didn't even know existed. So I'd rather hack it somehow because the housing is so nice... Unfortunately the HC-SR04 is about 4 mm wider so it cannot used directly.

The idea about contacting Knobloch is great, the sensor indeed has their logo printed on it. I'll do that and I'll post any findings here. Thanks again!

[rubem]

Unfortunately the guys at Knobloch did not answer yet, I'm not sure if they will. But in the meantime I found a sensor called RCWL-1601 (https://pmdway.com/products/rcwl-1601-u ... nce-sensor) that will easily fit into the housing, although the ultrasonic transducers will have to be repositioned horizontally a little bit.

The easily available and cheaper HC-SR04 will require cutouts in the housing, which is probably a bad idea.

There is also the GP2Y0A21YK0F infrared sensor. It has the advantage of being able to interface directly to the TXT because it has an analog output. Disadvantages are the more limited range (80 cm), less precision and non-linear output. And it will probably require a custom-made lid so it won't look like the original thing.

So here are my options: (The original sensor is shown at the top for reference.)

Designer_2021-03-05_11-09-17.png (113.58 KiB) 7631 mal betrachtet

[rubem]

Today my new RWCL-1601 ultrasonic sensors arrived, and they fit perfectly inside the original ft housing with no modifications except for the removal of the 4-pin header connector. The sensor has exactly the same width as the original PCB (upper left). I soldered four thin flexible wires on it and brought them to the outside as you can see. An unmodified RWCL-1601 can be seen in the lower left.

Ultrasonic_sensors.jpg (103.37 KiB) 7109 mal betrachtet

There should be no problems interfacing it to the Arduino because this new sensor is a direct replacement for the (wider) HC-SR04 (upper right).

[fishfriend]

Hallo...
Olny as a information. Conrad Elektronik has a different one. This has a different connector and ist "V2".
When i bought it, it cost me days, that the information and driver at the www was wrong.
In the shop they say "we sold 40 one, and no one ask us" .
They have only 3 Pins that they use, the trigger and the Echo are the same one.

May be it is possible, that they pulled the + on to the Signal Pin.
Best regards
fishfriend
Holger Howey

[rubem]

Hallo...
Olny as a information. Conrad Elektronik has a different one. This has a different connector and ist "V2".

Thank you, I didn't know about the "old" version. I bought these from Ali Express from a store called "EC-Buying Ali Store". They are extremely cheap (probably less than one Euro) even in small quantities.

[eumel]

Hallo ruben
Ich habe die Diskussion mit Interesse verfolgt. Für viele Anwendungen (z.B. das Umfahren von Hinternissen) reicht ein Abstandsbereich von 3 bis 30cm. Ich habe den Infrarot Abstandssensor GP2Y0A41SK0F (unter 9€ mit Kabel) am ftduino und TX-Controller erprobt. Er liefert am Spannungseingang Werte von 3000 (3cm) bis 300 (30cm). Die Versorgungs-Spannung von 5V habe ich an Pin 1 und 3 des I2C-Ports abgegriffen. Für den TXT benötigt man vermutlich noch ein Bauteil, dass 9V auf 5V herunterregelt (DC-DC Spannungswandler ca. 7€), da der TXT einen 3,3V I2C-Port hat. Ich habe den Sensor auf eine Bauplatte (45x15x2) mit einem Doppel-Klebeband aufgeklebt und am Gabelstapler-Modell vorne im 45°-Winkel angebracht. Im Gegensatz zum Ultraschall-Sensor liefert der IR-Sensor schnelle Werte, und so kann das Modell HIndernisse mit hoher Geschwindigkeit umfahren. Es gibt den IR-Sensor auch für andere Abstandsbereiche (z.B. GP2Y0A02YK0F 20 bis 150 cm). Es ist daher fraglich, ob sich der Aufwand mit den alten Ultraschallsensoren wirklich lohnt. Weiter Hinweise: https://starthardware.org/abstandsmessu ... ungssensor
Mit freundlichen Grüßen
eumel

[rubem]

Hi eumel,

Great, thank you very much for your feedback. I actually was tempted to buy the same sensor because it has excellent specs. There are also mini laser time-of-flight sensors with seem to be even better, and I'm sure I've seen them here in the forum somewehere (by Juh, I believe). But the temptation to make the thing look like the original was too high In fact the RWCL-1601 sensor fits perfectly and it gives results which are very similar to the HC-SR04, I assume that's enough for most models.

What I didn't mention yet is that I've installed and Arduino Pro MIni clone just behind the RWCL-1601. Thanks to some great pinout coincidences I was able to solder three of the four sensor pins directly to the Pro MIni. The whole assembly is sturdy and very thin (I removed the reset button) and it fits easily inside the ft housing. Here:

RWCL-1601 with Pro Mini.jpg (114.53 KiB) 6787 mal betrachtet

So far I'm using the Arduino to decode the signals from the sensor and send them to the outside world via I2C. I didn't test it with the TXT yet, but with the micro:bit it worked right away.

Greetings,

Rubem