Mini2440 and LCD 2x16 based on HD44780

Hello, 

I would like to use the LCD 2x16 display which base on HD44780 controller.
In order to do that I've connected it with GPIO pins provided by CON4:

CON4    LCD signals
-------------------
GPF0    E
GPF1    RS
GPF2    RW
GPF3    DB0
GPF4    DB1
GPF5    DB2
GPF6    DB3
GPG0    DB4
GPG1    DB5
GPG3    DB6
GPG5    DB7

I control each GPIO pins by /sys/class/gpio mechanism. I've checked and it
seems to work, but unfortunately LCD display doesn't respond.

Have you ever tried to use this kind of display on mini2440 and Linux?
Maybe I should use some different access to GPIO? CPU has 3.3V digital
level, so maybe it is a problem?

Thank you in advance for engagement any any hints.

-- 
Piotr

First thing I would do is get a datasheet for the HD44780 and determine
what voltage levels the LCD signals required.

Second thing I would go to www.avrfreaks.net and search for HD44780.  You
will find a lot of hits as it is a popular display.  I ran mine off a 5Volt
system. A high on a 3V3 system just might not be high enough to guarantee
proper operation of the HD44780.  You might have to get a level translator
chip or find a LCD display that will operate off 3V3.

Good luck!

I've just successfully run it! The previous error was related with wrong
voltage level of contrast pin in LCD module. It should be connected to the
ground.

In my case a 3.3V level is sufficient to guarantee a proper operation of
HD44780 controller. It supplies the LCD controller (Vd) and backlight
(LEDA).

If the /sys/class/gpio mechanism is used to control GPIO pins, it is
important to execute the fflush(file) function after setting value. It
immediately refreshes pins value

Thanks for interesting,

--
Piotr
http://www.embedded-engineering.pl/

Hi
   I have done on pc parallel port, Am interested doing this i have
micro2440 which has 20gpio lines so can you help on coding in linux.
thank you.

Hi
       I have a problem using the GPIO because i don't have a GPIO driver
and i don't have a /sys/class/gpio file pass.
Could any one help me for writing a GPIO Device driver or help me to find
the /sys/class/gpio pass and use it

Thanks for advance

Hi 
I'm new in using the mini2440 kit and i wanna to use the GPIO and i can't
use it , could any one help me to use the GPIO, or support me in designing
the GPIO driver

thanks

i am doing some experiment between arm9 mini2440 and HD44780 LCD display.
but i don't know how to make a driver for it ,and show the result on
display throught GPIO
do any source code can help me fix it?

Try to look at: drivers/staging/panel. This driver implement LCD driver.

since it is two different things,i just use a cable to connect them
it may not have a driver on mini2440