Before the smoke starts rising.....

Hi,

Before I try this I thought I'd just ask. I assume that if I want two arduinos to talk to each other, I can just connect one of the Rx pins on the 1st arduino to the Tx pin on the 2nd arduino (and vice-versa) ?

I'm assuming that no hardware buffers/level shifting is required. (i want to get a mega to talk to mini-pro). If this is ok, can anyone give me any idea over what length of wires it'll work? ( my project requires them to be about 3 meters apart)

cheers

Your correct. Provided that they both use the same voltage AND you connect there grounds. Are you sue the pro mini is using 5v and not 3.3v?

Mark

Tx to Rx & Rx to Tx...
Do use 470 Ohm to 1 K Ohm resistors between the two as a best practice.

Do use 470 Ohm to 1 K Ohm resistors between the two as a best practice.

@mrburnette

What! Why! You would not normally connect to digital chips (which use the same votage) using a resistor.

Mark

holmes4:

Do use 470 Ohm to 1 K Ohm resistors between the two as a best practice.

@mrburnette

What! Why! You would not normally connect to digital chips (which use the same votage) using a resistor.

Mark

I have had this issue before how. I had one arduino on and the other powered off. with the digital pins connected directly the 1 Arduino tried to power the other Arduino which was off through the I/O pins. I always thought you had to use resistors to limit this. what method is better?

I had one arduino on and the other powered off. with the digital pins connected directly the 1 Arduino tried to power the other Arduino which was off through the I/O pins.

I agree, the resistors will not produce a significant drop when both units working because the input current will be very small.
When one is OFF they will prevent any phantom power supply.

Tom

Risistors should only be used if you are termally stupid.

Grumpy_Mike:
Risistors should only be used if you are termally stupid.

And you're dead certain of that? :slight_smile: