LCD 4-bit mode affecting rest of port?

[Yuantu Huang]

Dear Sir,

The LCD works fine as long as the power is supplied non-stop. However, when I turn LCD power off and turn on again, LCD displays two line black square forever, similar to power on first time. The power of PIC18F8520 is always on (never off). The definition of LCD is as follows:

DEFINE LCD_EREG PORTA
DEFINE LCD_EBIT 2
DEFINE LCD_LINES 4
DEFINE LCD_RSREG PORTA
DEFINE LCD_RSBIT 0
DEFINE LCD_DREG PORTF
DEFINE LCD_DBIT 0
DEFINE LCD_BITS 8

Your help and advice would be very much appreciated.

Yuantu

[Ingvar]

The display needs to be initialized again, after poweron(and a pause) you need to do ......

Flags=0
LCDOUT blah,blah ,blah.......

/Ingvar

[Yuantu Huang]

Hi Ingvar,

Thank you very much. You are right. The LCD needs to be reset after the power is restored. I can use

lcdout $fe,$38
lcdout $fe,$0c
lcdout $FE, 1

to restore 8 data line LCD display. But the above did not make 4 data line LCD display work. Could you please give me some suggestion how to fix the problems.

Thank you very much.

Yuantu

[mister_e]

Sorry but Ingvar gives you the solution...
FLAGS=0

it's written in the PBP manual too.

[Yuantu Huang]

Hi Steve,

I thought FLAGS was a pseudo flag. Now I understand FLAGS = 0 is a LCD reset statement. It is working.

Thank you and Ingvar for your help.