Buttonless entry - need 12V source

[keyfob]

Hi all,

I am new to mazda forums. I am on a quest to rig my 2007 Mazda 3 so that I don't have to use a key. The first step was to get rid of my keyfob:

Big image here.

Basically, I am using the footpod of a nike+ipod (red thing on right) as active RFID. Sounds fancy but it's actually not too hard. The stuff in the middle of the picture, top to bottom, iPod breakout board, Arduino Pro, and the guts from my 2nd keyfob. All the electronics come from SparkFun but I don't want to sound like a spammer.

The idea is that I have all these electronics in my car, and the red foot pod thing in my pocket. As I walk up to the car, the foot pod sends out its unique ID, the electronics in car receive the 'known good' ID and then activate the 'unlock' button on the keyfob.

It actually works! My problem (sorry for the delay):

I don't have a clue how to find a 'hot' 12V line in my Mazda to power these electronics. They run at 3.3V @ ~20mA, minuscule, but I still need a real power source. And the cigarette ports shut off when the car is shut off (no good).

I saw the awesome post of the PJB and ECU by Rotus8, but I'm so new I don't quite follow the diagrams. I'm hoping for an answer of 'the orange wire below the glove box' or some such layman directions.

And for extra bonus points: What is the best way (signal or wire) to detect that the car's engine is running? This signal would help me more accurately figure out when to lock the car (after car shutdown, wait for lack of RFID, then wait 5 seconds, then lock doors).

Thanks!
Keyfob removal

 

[bgibb68]

well if it's wired the same the orange wire is a constant 12v that feeds the ignition and the ecu..... you could locate it in behind the column

and i have no idea about the bonus question

 

[icspots]

Wow, unique mod. Kudos.

There's definitely 12v constant somewhere at the PJB. You could go for the ignition, or HU as well. There's also 12v constant going to the maplights, and somewhere behind the driver's kick panel.... that's where they wire the auto dim mirror to.

 

[i like speed]

^he got the first question

As for the bonus question you could use the rpm sensor wire or if possible program your stuff to detect voltage. Power goes up 1-2 volts with the engine running.

Let us know how this works out. I was actually thinking about doing something like this. I've always enjoyed designing/building electronics and such.

 

[GoFast]

so you can figure out how to turn a key fob into an RFID but you can't figure out how to find a 12v constant power source?? geeesh (hand)(lol2)

 

[bgibb68]

so you can figure out how to turn a key fob into an RFID but you can't figure out how to find a 12v constant power source?? geeesh (hand)(lol2)

(ohsnap!)

 

[dmention7]

As for the bonus question you could use the rpm sensor wire or if possible program your stuff to detect voltage. Power goes up 1-2 volts with the engine running.

That is what I was thinking.

Props on a unique DIY!

 

[AWDthis]

Write a How-To dude, id do this! Two Thumbs up.

 

[denice25]

Welcome and Enjoy...

 

[keyfob]

@GoFast - I know. Horrible no? I can layout a printed circuit board but cars mystify me. Don't tell my mechanic.

@i like speed - Good idea. I can detect voltage changes with a little work. I'm worried that detecting
12V = car off
13-14V = car on
is a little hairy. What if battery gets low? 11V. And car starts? 12.5V? System might not think the car was on. The RPM wire is a solid idea. I'll look into it - thanks!

Thanks for the feedback! I just had to get off my butt and pop some panels back on the passenger side foot well. Probing around with a multimeter, I found a few 12V hot wires with car turned off. Perfect!

Tap splices rock! Way easier than trying to get my soldering iron out to my car.

Picture goodness:

Larger image

It may look all rather weird, but an interesting thing to point out in the above picture - the thing that says 'iPod Serial' upside down - that is the receiver. Notice the aluminum foil and heat shrink? That's to make the antenna worse. The system worked too well. The small pod in my pocket could unlock my car from 50+ feet away. The aluminum foil limits the reception to 10-15 feet. It's *awesome* to be able to walk up to my car and a few feet before I get to the handle, the car unlocks.

Larger image

Passenger side foot well with 12V wire tap.

Full tutorial write-up coming in a week or two. Will post link when done.

 

[bani]

you need to complete this with pushbutton start...

 

[StealthWyvern]

interesting!

 

[i like speed]

you need to complete this with pushbutton start...

True... You need to delete the ignition switch and make it so when you get close enough to unlock the doors it also turns the switch on. Hit the button and your off. Definately need a bypass switch so you can sit in your car without running the battery dead.

And write a how-to on this please.

 

[i like speed]

Also I'm pretty sure hacking up your keyfob was unnecesary. You could have easily wired the system into the power lock button inside the car. It might take a relay but it would be more reliable I think. This way would mean one less battery to go dead assuming it still uses a battery (I couldn't tell from the pics.)