16F628 Car starter

[Kostecki]

I am looking for a prototyping project for my next semester's class, and was hoping some more experienced users could help me out.

I am thinking of building an automatic car starter for my project, and was curious if a PIC 16F628 would be able to handle such a task. I am not a car person by any means, so I have no idea how I would
A) Build the receiver/remote
B) Implement said devices
C) Hook it up to the car

I know the 16F628 is able to handle a plethora of things, but is this one of them?

 

[Nigel Goodwin]

As it's a very basic and simple task, no problem.

 

[Kostecki]

That is good to hear, thanks much for the quick feedback. If I do end up persuing this project, I will be sure to post the schematics and program.

 

[jimlovell777]

It's more than capable, I did the same project a few years ago with a PIC16f627A. I still have the source code and schematics if you're interested. The code is written in C. The project also included car alarm and engine immobilization features.

 

[Kostecki]

It's more than capable, I did the same project a few years ago with a PIC16f627A. I still have the source code and schematics if you're interested. The code is written in C. The project also included car alarm and engine immobilization features.

Actually, that would be great jimlovell777! I would love to take a look at it.

I noticed you were talking about car alarms and such. The car I am going to modify is a 97 Cavalier, which has nothing "motorized" other than the door locks from the inside of the car. Some of the projects I have seen require modifying the panic button on the remote-lock system... but this car has none of that. Would your project work on a completely mechanical car?

 

[jimlovell777]

Yes it would work on a completely mechanical car though you'd need some form of wireless keyfob to use remote starting of course. I did include in my project an electronic keypad so I could start my car without a key securely and if that's good enough you don't need a wireless device.

 

[cdude20]

Is there any way I could get those schematics and such? I haven't been able to find anything on building one of these after more than a few hours of searching.

 

[LTX71CM]

If you're still looking for help send me a PM and we'll find another way to discuss it. This is something I can help with but doing it post by post would be very cumbersome.

 

[Oznog]

You want to ensure that the starter will not engage with the engine running, as this will damage the starter. It needs to disengage immediately once the engine kicks on, and that could be tricky.

You ideally want a fairly secure link. The car starting itself while in a closed garage could be dangerous!

Also, you're basically going to have a relay that jumps the RUN wire, bypassing the requirement to have a key in the car entirely. There's some safety issues there if you couldn't turn off the car! I'm not sure how this works, I've never had keyless ignition. I think you'd want to keep the car running for a maximum of say 5 or 10 min and disengage the RUN relay in favor of the key once the key's been inserted and turned to RUN, but I'm not sure how you'd detect that since the RUN line is already energized by the RUN-relay.

If it's a standard, you need to ensure it's not in gear before hitting the starter. Sometimes you put a standard in gear while parked to keep it from rolling on an incline as a backup to the parking brake.

A carb'ed engine may need the accelerator pumped to set the choke prior to starting. You couldn't do this on such a vehicle. You'd want a fuel-injected one.

Many newer cars use "smart keys" that make it difficult to wire around the starter. What you're doing is exactly the same as hotwiring a car, start it without a key by connecting wires together! The security features to prevent that may make it impractical to install a remote starter.

 

[picbits]

Smart keys are easy to get round - open up the key, remove the transponder chip and tape it to the transponder receiver on the steering column cowl.
Detecting the engine running is as simple as taking the tacho pulse and cutting off the starter after maybe 3 seconds (prevent burnout) or when the engine RPM is above 500rpm
More complicated is protecting your circuit from the voltage droop (sometimes down to 6v) and spikes while starting. You also need two seperate circuits for the ignition and starter. The starter side isn't too hard as the solenoid current tends to be fairly nominal but the ignition side can be tricky. Imagine leaving your rear heated window on and heater on full whack. When you put the ignition on there is going to be a lot of current suddenly being drawn.

"Commercial" alarm manufacturers often use 2 or 3 relays with a 40 amp rating in parallel just to be on the safe side. They also use 2 relays in series for the starter to act as a failsafe against one of the relays/driver circuits keeping the starter running.