As far as i know, the CAN bus is off when the car is off.
This means that, if only connected to the OBD port, all the AutoPi can do is draw power. Not particularly exciting.
If that is true, how would I go about implementing things such as remotely controlling my windows?
Does somebody have any experience regarding this?
My car is a 2012 Lexus CT200h and there are both an App/Cellular based and a keyfob based remote starter system as a factory option (not equipped in my car.
I have an aftermarket remote starter unit which only connects to the OBD port, some irrelevant wiring (to turn on the parking lights and check the hood switch) and a weird bus going from the main body ecu to an unpopulated connector “H90 Option Connector” with 2 pins: BTX and BRX. No further documentation whatsoever but I strongly suspect that the aforementioned factory options use this connector.
My car can also open the windows when holding down the unlock key, or open the doors when just pressing the unlock key. The latter may not seem spectacular at first, but in order to unlock the doors or open the windows, certain communication networks and certain ecu’s have to be active.
Alltogether it seems that my car has various means of triggering it to turn on the communication networks while turned off.
Im just not sure if there is a universal simple foolproof method for most modern cars, or a method that other people have had success with so far. I have not yet tried anything.
EDIT: According to a colleague who has done some CAN bus hacking before, the bus is always listening in pretty much all modern cars. If an “unlock all doors” command is sent, it will be processed and the doors will be unlocked without a prior “wakeup” packet/signal needed.
This would answer my question but I would like additional confirmation before making big purchases.
He did the CAN sniffing with a simple Arduino and some popular CAN to UART chip, claiming that it does the job and spending a fortune on CAN adapters is not required for getting into CAN hacking.
I think that it depends very much on the car, but I would think that some busses may be inactive when the engine is not running. But some busses, like the less critical and slower speed ones should always be active, like the ones controlling the unlocking of doors and in your case, rolling down the windows.
In the newest version, we have added the ability to record and replay CAN messages, so that users can record the traffic while performing some action, pressing buttons, unlocking the car etc, and then replaying various parts of the traffic to boil all the recorded traffic down to the messages that does what you need.
This is currently done via the terminal, but we are working on a GUI for it as well.
Regarding what equipment is needed, then no, if can traffic is all you want to retrieve, then there are probably cheaper hardware than an AutoPi, but the focus of our product is as much on the utilization of the CAN communication, as it is on the actual traffic, like after figuring out that some traffic is reporting a specific measurement, and then logging that data to the cloud and viewing it in a widget on the web dashboard, or discovering what commands is used to open the trunk or honk the horn, and then being able to activate that via an app or automate it via an home automation solution etc.
So it all depends on what you want to use it for, and what you might want to do later on.
First of, thank you for your elaborate answer, It answered some of my questions.
I figured that much of the interesting communications must be happening on a LIN bus, and I wonder if LIN is supported in the software by default. I wouldnt mind tapping more wires to connect them to a gpio. Im just not very good with software and kernel stuff yet so I’d rather have the required interfaces available beforehand.
I definitely want to buy an AutoPi and an android head unit to upgrade my car. Its just that I want to control many things in the car (doors, windows, horn, climate, maybe radio and maybe even driving mode or hybrid system monitoring), but I want to check if it is possible without months of reversing before making the big purchases.
No problem
Regarding if it’s possible without some reverse engineering then that’s a hard question to answer, there will be some reverse engineering involved with any car, depending on what you want to do.
Cars are different, has different busses, and different features all running on different busses, so it will require work to get all that to work.
The first step would be to check if anyone else has done any reverse engineering work already, as I expect that to be the most time consuming work in such a project.
One of the ideas with our device and cloud platform, is that people should be able to learn from each other, so that two people should not spend time reverse engineering something that someone else has already figured out.
And we are continually working to improve and expand this whole area in our system.
I’m looking to purchase AutoPi for car locking/unlocking, would like to know how was your progress in locking and unlocking the doors of your vehicle.
