So let’s say your using an Arduino in your project. You already have the hardware-based serial interface working with one portion of the project and need a second serial port for unrelated hardware.

[Jacob Geigle] had a problem. A GPS unit and a Bluetooth-to-serial were tying up all the hardware UARTs on an AVR Arduino project. “Software serial”, I hear you say. But what if I told you [Jacob] ...

Before opening the Arduino software, wire up the Arduino according to the circuits page using the 8MHz minimalist breadboard circuit but with a 10k pull-up resistor on the reset pin (physical pin 1).