OMG! After days of banging my head against a wall, I got my C2042A Devantech LCD05 to work with LCDi2cR!!!!
So to get it to work, follow the steps to fix the LCDi2cR library as I outlined above, THEN, download the i2cLCDguesser.zip from this thread: http://forum.arduino.cc/index.php?PHPSESSID=q0phasbvkliillk6nupirl2t65&topic=260510
What the i2c guesser told me was that the bootup i2c address display was WRONG!! No wonder the LCD was behaving like nothing was talking to it, because nothing WAS talking to it.
My LCD's bootup shows the i2c address at 0xC6, but the i2cLCDguesser says it is at 0x63. I also ran the i2cScanner (http://playground.arduino.cc/Main/I2cScanner
) as well, and it said the same thing.
With this in hand, I opened the LCD_Test example in the LCDi2cR library, and used this:
LCDi2cR lcd = LCDi2cR(4,20,0x63,0);
And voila! It works!!!
Who'd thunk it, the bootup diagnostics address display (which I thought was amazingly useful) was the culprit this entire time.
Btw, the factory documentation is here:http://www.robot-electronics.co.uk/htm/Lcd05tech.htm
It says the address range is: 0xC6 - 0xCE ( even numbers only ).
Well, mine is at 0x63, that's certainly not in above range.
Oh, also, I did originally try to add the pullup resistors between VCC SCL and VCC and SDA, but even when I connect the board's SCL/SDA directly to the Arduino's corresponding pins, it still works. The real key was the i2c address.