A note about random()

I have seen quite a few people struggling with the Arduino random() function. The problem lies in creating a simple random '1' or '0'. It is tempting to write

random(0,1);

But this doesn't work as it returns '0' every time. What random() does is to generate a random number from START to FINISH - 1.

random(START, FINISH);

So to get a random '0' and '1' returned you have to do this:

#define START 0
#define FINISH 1

random(START, FINISH + 1);

so it outputs from START '0' to FINISH '1'