Basic Feasibility Question

Hi. I'm new to the forums and to arduinos in general. I've been searching the web looking for an answer to an issue I'm having and don't seem to be having any luck.

I am looking to do a project where I have 2 arduinos (possibly need one to be a mega) communicating over RS-485. Arduino #1 would have 3 pushbuttons that would drive input pins low (or high) and it would send a signal to Arduino #2 that would have it toggle each of 3 pins, driving LEDs, low or high depending on the current state of each pin. In other words, the LEDs would toggle on or off and stay that way (latch) until the next time the corresponding button is pushed again on arduino #1.

In addition, I need to have arduino #1 driving a 20x4 LCD display using I2C (thus the reason #1 needs to be a mega). There will be other things going on also, but this is the basic problem I'm having.

I had found an example of the 3 pushbutton project online (non-latching, but I can fix that) a while ago but I failed to bookmark it and now I can't seem to find it again. If anyone could point me in the right direction, I would appreciate it.


I say as many helpers said before: Why go for 2 controllers? A simple UNO can do a lot and a Mega a lot more. Intercontroller communication adds more difficulties than most people would guess.

The reason for the 2 controllers is that the pushbuttons and the LEDs will be about 100 yards apart in 2 different buildings. Actually, the LEDs will be replaced with relays once I get it working. I've already got the comm cable in place.

Okey. I missed the info about wireless communication due to distance. Reading 3 buttons is no problem for almost every Arduino. What's the difficulty?

Sorry, You've got a comm cable....

The problem I'm having is that I can't find the original project on the web that I started working from and I'm not sure how to use I2C for the LCD along with the serial communication for the RS485.

Why sorry about the comm cable?

All of those things are included as examples in the Arduino IDE.

chopsuwe: All of those things are included as examples in the Arduino IDE.

OK, that's probably why I couldn't find it on the internet - I got it from the IDE.


You will need adapter modules for RS-485 communications.