I’m blind. After posting this question, I found the answer in the language reference after reviewing it a dozen times. The trouble is I’m told that I can’t delete my own message???!! So I’ve edited it out of existence.
Look at bitwise operators on http://arduino.cc/en/Reference/HomePage#.UwDBMmJ_s1I
imho a good book about low level Arduino - http://www.amazon.de/gp/product/1608454983/ -
I’ve seen |= used in several programs and I realize it has to do with setting bits in a register, but it doesn’t appear in the Language Reference.
I should be easy to find, right? Just google “|= arduino”…
Despite the fact that I can find several pages that use |= (but not explain it) not one of them shows up in the first few pages of a google search. I’m guessing google either ignores the symbols or they mean something else to google. Even writing them as +"|=" doesn’t work.
Searching for |= in the http://forum.arduino.cc search box (top of this page) doesn’t turn anything up either even though I find this snippet of code here:
//Timer2 Settings: Timer Prescaler /64,
TCCR2 |= (1<<CS22); // turn on CS22 bit
TCCR2 &= ~((1<<CS21) | (1<<CS20)); // turn off CS21 and CS20 bits
// Use normal mode
TCCR2 &= ~((1<<WGM21) | (1<<WGM20)); // turn off WGM21 and WGM20 bits
So, my question is, can anyone point me to a reference to explain how to use <<, |=, &=, etc. etc.
Go over the websites, Character 8 http://www.mikrocontroller.net/articles/AVR-GCC-Tutorial
They known as operators NOT symbols. They are explained in the reference section of this site along with many others.