TechKnowCase
Posts: 2
Joined: Sun Jun 17, 2018 6:45 pm

Playing with raspberry pi and negative voltage in a car

Sun Jun 17, 2018 7:51 pm

Hi everyone!

I have a rather complicated project, but most of it has a solution.

I want to do a "Viper" type smart remote starter, but of course way cheaper and more customizable. It would have a remote start with an app on my phone, multiple Aux options(rolling windows down, heating the seats, etc), a GPS to track where my car is (just in case, or to make sure my gf is not trying to get away with it :lol: ).

On my way on the DIY route, I found no information about the "data-link" (call it iDatalink, DBI, D2D, RS-232, DEI) serial port and have no idea how it really works. I have this feeling it would be easier though.

Long story short, on the hardware side of thing, I would use a (DC) 12v to 5v converter to power the rpi, the 12v to 5v to 3v3 logic converter (yeah I know, tell me if you have any better solution, ebay doesn't seem to have any) and some relays.

Where I'm stuck is on the schematic of the bypass module / CAN interface. It has a couples of negative voltage going to and from the remote starter (the raspberry pi in this case). I have absolutely no idea how to use it. I searched a bit around the web but nothing to make me 100% understand what to do.

If you have any suggestions for anything that might be doing wrong, what ever it could be, I really appreciate it too!

The car for the project is a 2016 Subaru BRZ manual Sport Tech (push to start)
(Here's the schematic P.17)

Thanks again!

Alex

User avatar
mark3112
Posts: 35
Joined: Mon Apr 09, 2018 10:39 am

Re: Playing with raspberry pi and negative voltage in a car

Mon Jun 18, 2018 1:04 pm

At a guess it looks like the +/- indicate the Active Level of the signal.
So The Brake Status is true when + (12V)
Trunk Status is true when – (0V)
You can make a real CPU in a FPGA, but you can’t make a real FPGA in a CPU.

TechKnowCase
Posts: 2
Joined: Sun Jun 17, 2018 6:45 pm

Re: Playing with raspberry pi and negative voltage in a car

Mon Jun 18, 2018 9:34 pm

mark3112 wrote:
Mon Jun 18, 2018 1:04 pm
At a guess it looks like the +/- indicate the Active Level of the signal.
So The Brake Status is true when + (12V)
Trunk Status is true when – (0V)
That could make sense! I'm going to have to try it.


Thank you!

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