Arduino random seed with EEPROM

arduino-random-seed-mem.cpp

/*
Arduino's random() function repeats when the program resets.

The typical solution is to seed it with a floating analog pin reading.
The problem with that is that the analog pin is not really random either
so you still end up with sequences that repeat fairly frequently. It also
requires you to give up an analog pin.

This gist attempts to solve these problems by storing the previous seed 
in EEPROM and incrementing it each time the program resets.
It stores a 16-bit word so the seed will repeat every 65,536 resets.

Keep in mind that the EEPROM writes are limited to ~100,000.
*/

#include <avr/eeprom.h>

void setup() {
  uint16_t seed = eeprom_read_word(0);
  randomSeed(seed++);
  eeprom_write_word(0, seed);
}

void loop() {
  random(0, 100); // use random() as you normally would
}