RS485 Hardware Network 1 – Getting Started

For another project I’m currently working on, I need a way to control multiple microcontrollers in a multi-point, multi-drop network configuration. Luckily, we live in amazing times. As I write this, you you can buy a fully assembled breakout board for the MAX485 chip from Maxim Integrated for a mere $0.45 USD shipped from China.

I bought a 5 pack, here are some of the boards:

RS485 is an old protocol, but is the logical next step for devices I’m already communicating with via RS232. For this example, I’m using 4 Arduino boards of various types.

  • An Arduino Micro as the master
  • 2 Slave Arduino Leonardos
  • 1 Slave Arduino Pro Mini (5v)

Here is a video of the setup:

The schematic is really straightforward as well. The only tricky bit is that I’m using a software serial port on each of the Arduinos for ease of debugging. Here’s a schematic:

The code to acomplish this is really intuitive as well.

Here is the code for the master Arduino:

This is the code for the slave Arduinos:

In subsequent posts, things will start getting more advanced. For now however this should be enough to start from scratch.

Thanks for reading.

Hey! This post was written a long time ago, but I'm leaving it up on the off-chance it may help someone. Proceed with caution. It may not be a good idea to blindly integrate this code or work into your project, but instead use it as a starting point.