Button that not only starts, but kills engine...how is this done? (new nissan)

[r6speed]

So Im sitting here in a hotel (out of town working) and watching tv. I notice the new nissan comercial comes on and the car has a push button start (much like my dsm But then I notice the button says "START STOP" This to me means that this button also kills the car. How could this work? I don't get it, the way a push button start works is the button transfering power to the starter when pushed. So if you hit this button again it would just grind your starter...

My only and I'm sure wrong theory: This is setup to some sort of time relay so after you push it (engines starts) it has like a 10 second spand then if you push it again a relay of some sort triggers it to kill the coil? This is the only thing I can think of, any ideas?

 

[voodoogsx]

It might go something like this:

The car has a Car_On_State() value that it looks at.
If you have a bluetooth key, it looks for the signal so it knows that it can engage the ignition if the start/stop button is pressed. This is like a regular key so you can't just start the thing at random.
When the bluetooth signal is close enough it activates the start/stop switch to look for a button press. At this time the Car_On_State() is FALSE since you were far enough away from the bluetooth signal or the car was already off.
When the button is pressed, the car turns on and the Car_On_State() value is set to TRUE
So when you press the start/stop button again it looks at the Car_On_State() ,and if it's TRUE, it turns off the car. It also most likely has a way to detect if the car is moving or other variables that might prevent the car from turning off, so if you accidentally press the button, it won't kill the engine.

That would be a simple way to do it....

 

[greddyturbo19]

i have a 2007 nissian altima with the push start. its sweet as hell. there is no key at all with the car just this transmitter all you do is push down on the brake and push the button that says start/stop to start the car then when you want the car off just press the button again and the car shuts off. and also if you just want the radio on and not the car you just press the button without holding down the brake. i love the car not having to deal with keys.

 

[voodoogsx]

bluetooth key == transmitter, I should have clarified that. It could be any type of transmitter really...bluetooth is just one type.

 

[knochgoon24]

Even easier than that.

They probably use simple electronic logic chips. With the car off, it has no power. In computer terms, this is a 0. When the button is pressed, you put power to it. The energized state in computer logic is represented by a 1.

The circuitry could use a D-Flip Flop to add the 0 and the 1 to get a 1. Then, when it's pressed, power is put to the circuit again. It adds the old 1 and the new 1, but since we're working with electronics, instead of getting 2, we get a 0 and the car shuts off.

If the circuit has power (1 state), it trips a relay that keeps the car running, kinda like having the key in the ON position. When the circuit has not power (0 state), the relay isn't tripped and the car turns off, like a kill switch.

To control the starter, an AND Gate is used. It "checks" to see if the car is running or not. Then, as long as the button is pressed and the car was off, the starter will crank.

The animated schematic below is a basic setup using a D- Flip Flop, an AND Gate, and 2 Relays. It's the basic idea. Hopefully it clarifies what I was trying to explain. Less than $10 for all the parts.

Since it took me so long to draw that all up, I see you are now using a remote. Same deal, just the remote trips circuitry that does the same thing as pushing the button.