Car auxiliary lights controller.

[Snops]

Hi.
It is getting very dark very soon here in Finland and thats why I've bought few auxiliary lights for my car.
I'm planning to control those light with microcontroller (ATMega168PA).

The plan is to use existing headlight power (high beam) as signal to mcu so i can enable/disable aux lights with quick double blink for example. Original headlights will be in use still of course.

I'm thinking to use just simple n-channel signal mosfet to drive 5V signal to mcu input (see attachment). 12V to gate and drain to input with pull up to 5v.

I also want to make this circuit future proof, so what if original headlights are pwm powered? Can I just use that circuit and make software changes or just forget about that and take new approach?

Also there is this canbus/monitored headlight thing so this mod should not draw a lot of current (few milliamps max).

So,
Is my circuit ok?
What about pwm headlights as signal to mosfet?
Canbus worries?

Edit. ...and of course mcu will control relay that gives power to auxiliary lights etc.