Available LCDs and libraries

[adwsystems]

How are you plugging in the LCD? Are you removing/attaching the 4 pin i2c cable while the Arduino is powered?
It could be creating a power glitch on the Arduino board.

I mean plugging it in, as in plugging it in for the first time. Not disconnect and then reconnect. I mean I'm an idiot and forgot to plug it in when I downloaded the sketch. Many projects, many LCDs, few Arduinos, with even fewer near the programming computer.

R/W is connected to pin5 aka P1.

I have gone ahead and done all the library related things you have listed. As I mentioned, I had replaced my sketch-LiquidCrystal_I2C directory with the contents fm's library. I have now deleted both the sketch and the IDE LiquidCrystal directories and unzipped (the non-MAC) files into an IDE directory called LiquidCrystal. It seems to be working. During detection now, the backlight is on as well as all of the LCD dots. Is it supposed to be like that?

I'm glad the instructions on installing this library are clear as mud. LOL.

[bperrybap]

R/W is connected to pin5 aka P1.

ok so R/W is hooked up to the PCF8574. Most backpacks are this way.

I have gone ahead and done all the library related things you have listed. As I mentioned, I had replaced my sketch-LiquidCrystal_I2C directory with the contents fm's library. I have now deleted both the sketch and the IDE LiquidCrystal directories and unzipped (the non-MAC) files into an IDE directory called LiquidCrystal. It seems to be working. During detection now, the backlight is on as well as all of the LCD dots. Is it supposed to be like that?

Not sure what you mean by "It seems to be working" or "During detection now, the backlight is on as well as all of the LCD dots".

When the LCD powers up before it is initialized, one row of characters on a 16x2 LCD will be "blocks" with all pixels for each character position turned on. The other row will have its pixels off.
Once the LCD is properly initialized all the pixels will be cleared.
The guesser sketch attempts to initialized the LCD and then print the constructor on the display.

I'm glad the instructions on installing this library are clear as mud. LOL.

Part of the problem is that the Arduino guys change the IDE constantly (way too often in my opinion) so it can be difficult to make one set of instructions that can work for different releases of the IDE.
There are also some things that can make things easier on newer releases that don't work on the older releases.

[Paul__B]

The unit is an Arduino Uno and genuine as far as I can tell. (I ended up with a counterfeit one, but am not using it especially for debugging). The crystal says 16.000, I'm assuming MHz.

It is, but the crystal is not connected to the ATmega328.

Nevertheless, the UNO runs at 16 MHz.

[adwsystems]

When the LCD powers up before it is initialized, one row of characters on a 16x2 LCD will be "blocks" with all pixels for each character position turned on. The other row will have its pixels off.
Once the LCD is properly initialized all the pixels will be cleared.
The guesser sketch attempts to initialized the LCD and then print the constructor on the display.

On power up, I see the backlight and one row of dot on, the other off. When the guesser searches and finds the LCD, the LCD is on with all dots on both rows lit. After I click send, the LCD blinks 3 times and then the constructor appears with the backlight on.

[bperrybap]

On power up, I see the backlight and one row of dot on, the other off. When the guesser searches and finds the LCD, the LCD is on with all dots on both rows lit. After I click send, the LCD blinks 3 times and then the constructor appears with the backlight on.

It sounds like it is working now.
Although I've not ever seen a LCD turn on all the pixels after probing.

What changed or what is being done differently?
Previously, it sounded like text for the constructor never appeared on the display.

[adwsystems]

Unfortunately I followed the instructions for adding libraries to the IDE. Based on the discussion here, that is not correct (or doesn't work, pick your poison). I made all the library related changes you listed. Initially I had just replaced the fdebrabander library in the sketch-LiquidCrystal_I2C directory with the contents fm's library. I since deleted both the sketch and the IDE LiquidCrystal directories and unzipped (the non-MAC) files into an IDE directory called LiquidCrystal.

Not sure how anyone new to fm's library would come to the conclusion this was the proper method. But if it works...

[Nasa]

I first had problems making my program compile using the Arduino IDE until I found I had multiple LCD libraries. Some of the libraries are located in C:\Program Files (x86)\Arduino\libraries while on mine some libraries are located in C:\Users\xxx\Documents\Arduino\libraries . I deleted all LCD libraries and installed LCD_I2C Library found on http://playground.arduino.cc/Main/LCDI2C . Good explanation on the libs here also.

After that I have had no problems.