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
Mini2440 and LCD 2x16 based on HD44780
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?
since it is two different things,i just use a cable to connect them it may not have a driver on mini2440