Go Down

Topic: Help reading RF data from vehicle key, willing to pay (Read 3879 times) previous topic - next topic

Lynton

I have over the last few months been trying to read the rf data sent by a vehicle key. I have used a simple 433 mhz receiver connected to an Arduino Uno. If i send a signal from a cheep home remote control (3 button device for garden lights) the Arduino reads it and sends it to the serial monitor. Iv done this using a downloaded program and RFswitch library. The data is displayed showing the different code each button sends. this proves the Aurduino and RF receiver is connected and working correctly.

When i press the button on the vehicle key fob nothing happens, this i believe is the data being sent is not compatable with the RF switch library. The rf switch library data sheet says it will only accept data sent from certain chipsets.

So i need some help in either writing a program that will read and display the data being sent by the key of find a program or library that will do it.

The data being sent by the key is around 77 bits long binary, which when converted equates to 6*2 digit hex numbers. it is these hex number i want displayed via the serial monitor.
Im willing to pay for any help or time given in acheiving this.

Paul_KD7HB

Did you look at the frequency used by your vehicle key fob? I just checked mine and it uses 315MHz. Quite a ways from 433MHz.

Paul

Wawa

Are you planning to break into cars.

AFAIK, car keyfobs use a "rolling code".
Every next keypress is different.
Leo..

Lynton

Hi Thanks for the reply, the key frequency is definately 433 mhz, im in the uk and most vehicles here use 433 mhz, 315 mhz is usually only used in America and Japan.
I know the keys use a rolling code i want to be able to read the code that is being sent ie before it is decoded by the vehicle.
 

PaulS

Quote
So i need some help in either writing a program that will read and display the data being sent by the key
Why do you need to do this? That code will NEVER be sent again, and after the car accepts it this time, will NEVER accept it again.
The art of getting good answers lies in asking good questions.

Lynton

I have the need to produce replacement RF key fobs keys for customers cars.
The Key Fob computer system calculates the working fob codes from the raw data sent by a working key. you insert the key into the rf receiver coil and press the unlock button 3 times the computer then gives you a key report which includes, the rolling code, the key number , etc. this works fine and we use it daily.
If a customer is miles away, he has to post his working key (most customers only have one working key)to enable us to produce a new key. This means they cant use vehicle whilst the key is away.

The plan is to use an Arduino+rf receiver, post to the customer they turn the unit on, hold thier working key nearby, press the unlock button 3 times, if the Arduino receives a valid code the Arduino then turns on a green light. The customer then post the Arduino back, I recover the RF sent data from the Arduino and produce a new working fob for the vehicle. 

This allows the customer to get a new key without sending his only working key away.
Also the Arduino rf receiver is fairly low replacement value so ok to send through post.   

PaulS

I'm nearly certain that the responses you got here would have been far different if you had posted that information up-front.

Quote
When i press the button on the vehicle key fob nothing happens, this i believe is the data being sent is not compatable with the RF switch library. The rf switch library data sheet says it will only accept data sent from certain chipsets.
This seems highly likely, as something needs to modulate the carrier frequency on the sending end, and something needs to de-modulate it on the receiving end. I would imagine that part of the security involving the key fobs involves not disclosing details of the modulation/de-modulation process except to authorized recipients.

Have you discussed your plans with the vendor of the machine you use today? Perhaps they would be willing to help with the de-modulation part of the code, if they accepted your assurances that use of the device is open and above-board.
The art of getting good answers lies in asking good questions.

JJUANTHEMAN

I've been a locksmith for 15 years this is a project I would be interested in too.

Go Up