USB RS232 to RS485 Converter Dongle

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About

This USB dongle will convert RS232 to RS485 for use with the lighting system. It's generic enough that anyone doing an RS485 project should benefit from it.

Design

I borrowed from Sparkfun's design for their USB-to-UART FTDI FT232RL breakout board as well as the examples on the FT232RL datasheet. Then, I added a SN75176B (a MAX485 clone), configured for data output mode and two RJ-45 jacks. A 120Ω resistor is needed if you are terminating the lines.

There's a few status LEDs showing power, TX, and RX status too.

Schematics and Layout

These files contain the full plans for the board. I use Kicad for schematic capture and board design.

I found all the parts I need on Digikey, but it's possible to get some of them cheaper on Avnet.