LCD custom characters defined at beginning

Using Arduino Programming Questions
1

I'm writing my own library for the LCD with the idea to get in-depth knowledge of the process and the last thing that I didn't implement in it was the custom characters.

I came up to the problem, where if I don't reset the cursor and clear the display, I can't write anymore after the write to the CG-RAM .... , which forces me to create the custom characters at the beginning and then reset the cursor.

Then I checked the example of the official library to test if the same problem is present in it too and it is:

 lcd.begin(16, 2);

  // create a new character
  lcd.createChar(0, heart);

  // set the cursor to the top left.
  lcd.setCursor(0, 0);

  // Print a message to the LCD.
  lcd.print("Hi:");
  lcd.write(byte(0)); // when calling lcd.write() '0' must be cast as a byte

The characters are first created, then the cursor is reset to 0,0. If we skip that no character will be printed, but why?

2

Please post code that compiles.

And which of the several LiquidCrystal libraries are you using?

3

It’s down to the way the library is written . Whoever wrote it wanted it to work that way! You position the cursor and print .

I think you need to list your complete sketch to illustrate your point which is not fully clear .

You can look at the library files yourself and work out what is done and how with create character etc and how they are dealt with

4

There is a problem with the library, createChar calls the command for setting value to the CG-RAM, but doesn't return to DD-RAM.
Because of that, in their example they all setCursor, which does exactly that.
But that creates a problem.

  • If you want to create a character after you have written something to the display, you must revert to DD-RAM, but you must know the position of the cursor, which it was before writing to CG-RAM ...

The solution is simple :slight_smile: Just keep a record, where you cursor's position was and set the DD-RAM to it.

5

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