Linking outputs to inputs on two arduinos

I have searched but am unable to find an example of how you could connect the output from one arduino to the input of another.

I would like to send an output high to turn a led on and at the same time start a timer going which is running on a different arduino.

Just link the output straight to the input? or would I need a pull down resistor?

Hi crazynight

How far apart will the Arduinos be?

It could be as simple as connecting a digital pin from first Arduino (in output mode) to a digital pin on second Arduino (in input mode). Connect the grounds of both Arduinos. Don't need pullup resistor.

Then, in the program on your second Arduino, check the state of the input pin each time round loop() and start the timer when you see it change state.

Out of interest, why are you using two Arduinos instead of one?

Regards

Ray

Thanks for the reply, there distance apart is TBC possibly 15ft or maybe next to each other (30cm), one will be operating a timer with a 4x7 seg display and the other will be controlling the logic of monitoring for objects on a beam break system and turning on LED's.

Ultimately I may have 3 or 5 linked together depends how my design goes; I prefer separate stand alone items which talk to each other rather than 1 doing everything especially when timing is involved.

I've not connected Arduinos over a distance of 15 feet.

I would think that using shielded cable (with shield connected to GND) would be advisable.

Hopefully others with direct experience will comment.