Emergency gear is expensive. One of my other interests is being a Skywarn storm spotter.
This code emulates the brains of a Whelen Slimlighter, a $175 led-flasher, that hopefully makes other drivers aware of your presence. The main feature of the slimlighter, beyond the ability to flash two panels of very bright LEDs, is it's ability to select different flash patterns with a momentary pushbutton. This code does the same thing, in an AVR2343. You can customize the flash patterns with single byte elements that determine which LEDs are on or off, and for how long.
External hardware needed: 5V power supply, N/O pushbutton on pin 5, MOSFET led drivers on pins 2 and 3.