RTL_433 Tpms reading from Android

 New car, new problems. This page is mostly here for me to document what i did.

So. i got myself a Renault megane mk3 station wagon. The old Getz was no longer able to run in the cities because of having no particle filter.

Having BEGGED the wife for something RWD i ended up with this car. A FWD diesel eco car. The reason it was this specific type, is because the cabin is big enough for my kids.

Now this car has tpms sensors, and therefore i need sensors in the new summerwheels im getting.

So i needed a way to read the sensors.

I tried working with DTT4ALL but no luck. I will keep trying, time allowing, to see if i can switch to indirect tpms.

Until then, i need to figure out what tpms sensors are in the car, and what id they have, so i can clone them.

Having gone through a couple of different directions, i ended up with thinking rlt_433 was a path to follow. 

Searching the internet, i found rescourses like.

These about arduinos:

https://forum.arduino.cc/t/decoding-433-92-mhz-fsk-signal/486047/5 

And these about more general computers

https://github.com/jboone/tpms?tab=readme-ov-file

https://github.com/merbanan/rtl_433/issues/2978

https://www.rtl-sdr.com/testing-tire-pressure-monitoring-system-sensors-with-rtl-sdr-and-rtl_433/

This dude that made a translator from one type of tpms to another..

https://forum.arduino.cc/t/tpms-transcoder-for-renault-zoe2-with-cc1101-and-arduino-nano/1363151

Basically they ended up leading me to this piece of software

https://github.com/merbanan/rtl_433/tree/master

And the links ended up leading me to how to use the software, and what i needed

So i bought a dvb-t receiver with a RTL2832U chip, hoping it would work

Then got to work. My main laptop is using Debian 12, so a quick apt install rtl_433 later and bobs your uncle, i got a scanner.

Now some of the pages above suggest scanning the wheel sensors without an antenna, but i didn't work for me. When stationary i got no results, and the only result i got from driving around, was a single citroen sensor. Not good.

Having the laptop in the car wasn't nice either,

so i started googling rtl_433 and arduino.

and i got to THIS page.

It suggested installing Termux and ubuntu and using it.

Now being a jackass it took me the best part of the morning to get it working.

Here's a quick howto, but go to the link to see a better walk through.

1. install SDR driver from the play store https://play.google.com/store/apps/details?id=marto.rtl_tcp_andro

2. Install Termux https://play.google.com/store/apps/details?id=com.termux

Now i go on a side path, from what Dobrou did.

in Termux i did.

apt update && apt upgrade -y

apt install -y proot proot-distro

proot-distro add ubuntu

The reason is that i couldn't get AnLinux to work, and i didn't have time to fiddle. My guess would be that if i had installed proot and proot-distro, AnLinux would have worked.

Back to the fun.

i added a usb-c hub, Clamped in my dvb-T adapter

I opened the rtl-sdr driver, chose advanced and entered

-a 0.0.0.0 -p 14423 -f 433920000 -S 1024000 -T 0.

Then i started the driver. I found out that stopping RTL_433 in ubuntu, makes the driver stop.

The in Termux i started Ubuntu.

proot-distro login ubuntu

Again i divert from Dobrou. i did a

apt update

apt install rtl_433

Then i was set ready to play work.

The first command i tested, showed me that one of my neighbours have a 433mhz weatherstation.

Fun as that was, i didn't want that data.

I ended up with the following command to run the scan

 rtl_433 -M level  -S known -R 90 -R 168 -R 212 -d rtl_tcp:127.0.0.1:14423

The flags meaning

-M Level: Show signal level

-S known: Save every known signal, as a .cu8 file to look at later.

-R 90/168/212: Only look for these known signal types... Since i have a Reanult, those are the signals i look for.

-d rtl_tcp:127.0.0.1:14423  : This would apparently let us connect to a remote sensor, in this case we connect to localhost port 14423. its NOT a coincidence that the port number is the same as the -p parameter in the rtl-sdr driver.

Then i went driving.. And i found out my cars TPMS are very active the first 5 minutes of a drive. Then they seem to slow down.

Once i stop, they stop transmitting as well

Long story short, i got about  40 files, that i then moved from my phone to my computer  using scp. 

Woops. 

apt install openssh

There we go

Now to look at the data, on my laptop i did

rtl_433 -a *-cu8

For some reason, i didn't get the same amount of samples.

The sensors identify as

Abarth-124Spider and Renault-0435R

And i wont show the id's here, as you could potentially track the car using it.

From the pressures shown, i have the sensors placed at

Front               ;1;4;7;26;29;32;36:40                     :Pres 94/256 

Front               ;2;5;8;10;12;15;18;21;23;35;39      :Pres 92/260

Right  back     ;11;14;17;20;25;28;31;34;38          :Pres 88/217

Left back        ;3;9;13;16;19;22;24;27;30;33;37    :Pres 90/205

Funny thing the low preassure is from the Abarth-124spider amd the other is from the Renault-0435R.

i suspect its because of different encoding.

I think that before i mount the new sensors, i need to do a trip in the car, with just 1 sensor wheel on at each time.

The pressure and temperature is generally rising as i'm moving along.

Anyways. I think i have the sensor id's that i need, to order new sensors :-)

Looking into https://github.com/merbanan/rtl_433/blob/master/src/devices/tpms_renault_0435r.c

we see that one of the cars mentioned in the file, is the Megane III GrandTour, this fits

Then we see that the pressure is in 4/3 KPA. So the conv factor CF= 0.1087785

meaning that the pressures are 256=27,8;260=28,28;217=23,3;205=22,299 ( this tyre has a leak of some sort)

These pressures are what the system reports in the dash.

So using theese i have now contacted a company in Poland.

The reason being, that this company seems to be willing to program the sensor, with the original Id number (cloning) for free.

They also seem to be having an ok price for the sensor

https://www.ladnefelgi.pl/product-eng-71201-TPMS-pressure-sensor-for-Renault-Megane-III-2008-2017-407000435R.html

So thats where this post will end for now.

I am waiting for an answer, to see if my Id's seem to make sense.

If they do, i will order the sensors, and hopefully i can get my summer wheels going.