AVR-Chat

On Apr 30, 2005, at 2:50 AM, Farzlina Ab.Hadi wrote:

> hi..when i power up the lcd, it will display the two rows of blocks. 
> it only
> display correctly if i power cycle or i reset my circuit.
> does it mean that i need to increase the delay after i power up the 
> lcd or
> some init problems?

Yes, it means one of those two things.

> fyi, i use ksu0069 lcd and i followed the init procedure as in the data
> sheet.

Pay particular attention to the synchronization stage where the 
controller probably resets into 4 bit mode. You don't necessarily know 
if its in the high or low 4 bit stage of an access. If you run the 
interface 8 bits something like this will ensure its in 8 bit mode. I 
haven't seen need to edit my lcd.c file since 1994.

/*
  *	Make sure LCD is in 8 bit mode, 2 lines, font 0
  */
void lcd_sync()
{
	rs_port	&=	~rs_bit;
	e_port	&=	~e_bit;
	rw_port	&=	~rw_bit;	/*  write			*/
	lcd_dr   =  OUTPUT;		/*  change to outputs */

	/*
	 *	If currently in 8bit, 4hi, or 4lo states
	 *	this sequence will end up 8bit
	 */
	wait_ms(15);
	lcd_data = 0x38;		/*  lo nybble second */
	e_port 	|= e_bit;		/*  set E to write 	 */
	e_port 	&= ~e_bit;		/*  end of write	 */

	wait_ms(15);
	lcd_data = 0x38;
	e_port 	|= e_bit;		/*  set E to write 	 */
	e_port 	&= ~e_bit;		/*  end of write	 */

	wait_ms(15);
	lcd_data = 0x38;
	e_port 	|= e_bit;		/*  set E to write 	 */
	e_port 	&= ~e_bit;		/*  end of write	 */

	lcd_dr = INPUT;
	rw_port |= rw_bit;
}

--
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.