User defined graphics in 16x2 LCD (HDD44780)

Vizier87 · Sep 17, 2012

Hi guys,
As I started using the LCD further, I'm stuck at the instructions I read from the manual. Basically it says:

1. Display on/off cursor commands
2. Clear display
3. Set display address
4. Display data 0x00 to 0x07
5. Set CGRAM address
6. Enter data to build the character

Basically I'm trying to display the character "lambda" λ.

Here's my code: (My portd pins are reverse to the data pins, sorry )

C:

     rs=0;
     portd=0x01; //display address 0x00
     enter ();

     //Entering "garbage bits" for display//

     rs=1;
     Delay_us(100);
     enter();

     portd=0x00;
     enter ();
     portd=0x80;
     enter ();
     portd=0x40;
     enter ();
     portd=0xc0;
     enter ();
     portd=0x20;
     enter ();
     portd=0xa0;
     enter ();
     portd=0x60;
     enter ();
     portd=0xe0;
     enter ();

     ///////////////////////
     rs=0;
     portd=0x40;     // Set CGRAM Address: 0b01AAAAAA
     enter ();

     // Start defining character /////
     rs=1;
     portd=0x10;     ///
     enter ();         //
     portd=0x10;       //
     enter ();         //
     portd=0x20;       //
     enter ();         //
     portd=0x20;       //
     enter ();         //
     portd=0x60;       ///
     enter ();           ///  LAMBDA
     portd=0x50;       ///
     enter ();         //
     portd=0x50;       //
     enter ();         //
     portd=0x88;       //
     enter ();      ///
     //////////////////////////////////

I think I'm nearly getting there (displays some rubbish). Anyone can advise on the code?
Also, how do I access the same character again? Is it by entering the same data as defined by the CGRAM?

Thanks everyone.
Vizier87

Ian Rogers · Sep 18, 2012

This is my bar graph... I define the characters first

Code:

rom char lcddef[]={	0x10,0x10,0x10,0x10,0x10,0x10,0x10,0x00,
			0x18,0x18,0x18,0x18,0x18,0x18,0x18,0x00,
			0x1C,0x1C,0x1C,0x1C,0x1C,0x1C,0x1C,0x00,
			0x1E,0x1E,0x1E,0x1E,0x1E,0x1E,0x1E,0x00,
			0x1f,0x1f,0x1f,0x1f,0x1f,0x1f,0x1f,0x00,
			0x00,0x00,0x00,0x14,0x14,0x15,0x18,0x00,
			0x1e,0x10,0x11,0x1c,0x10,0x11,0x10,0x00};

And insert them in one loop

Code:

LCDcmd(0x48);
	for(x=0;x<56;x++)
		{
		while(LCDbusy());
		LCDdata(lcddef[x]);
		}

The characters are then 0 - 7 AND 8 - 15 ( on most devices )

LCDdata(6); will print the last character ( I only use 7 )

Vizier87 · Sep 18, 2012

Hi Ian, thanks for the code. I'll read more into it. My C is still basic, I haven't got into the details yet.

Vizier87

User defined graphics in 16x2 LCD (HDD44780)

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User defined graphics in 16x2 LCD (HDD44780)

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