Re: [Lcd-linux] Connecting HD44780 to AT91SAM9260

[Anselm B. <ab...@cs...>]

Ah ok, I see. I was hoping there is some fancy wrapping from the lcd driver class to the specific driver, because writing to the device results in some strange behavior of the LCD. But I think the problem is the I/O-code, so I still have to work on that.

I will post, if there is some progress...

Regards, Anselm


Am 14.07.2010 um 11:17 schrieb Mattia Jona-Lasinio:

> Hi,
> 
> I'm sorry, but what do you mean by an 'hd44780 device'? The important
> point is to have in the dev directory a character device with major
> number 120 and minor number 0 and this is the char device you have to
> write to/read from. The name in itself is not important. In the
> documentation I assumed this to be /dev/lcd but can be whatever else.
> To be more precise, since lcd-linux can virtually handle up to 256
> different displays (with major number 120 and minor number from 0 to
> 255) I assumed the name to be something like /dev/lcd0, /dev/lcd1 and
> so on, but again, the name in itself is not important. The creation of
> the char device is handled by the udev service, but for this to work
> you need to install the file 60-lcd-linux.rules in the appropriate
> place of your distribution. If you don't have the udev service, you
> need to create the char device by hand, with mknod.
> 
> Hope it helps.
> 
> Regards,
> 
> Mattia
> 
> On Wed, Jul 14, 2010 at 10:38 AM, Anselm Busse <ab...@cs...> wrote:
>> Hi,
>> 
>> I am working on a similar setup right know. Only difference is that I use a AT91RM9200 and the data pins of the LCD are connected to the data bus of the MCU, so the LCD is memory mapped.
>> 
>> I have already modified the read and write functions and getting "reactions" from the LCD. But right know I am a little bit confused about the device interface. I have only a hd44780 device in my /dev tree but the doc says there should be a lcd device. So do I have to write to the hd44780 device to get an output on the LCD or is there something wrong because of the missing lcd device?
>> 
>> Oh and I have compile the driver statically into the kernel. In case this is important.
>> 
>> I would appreciate some help about this issue and will of course post my results if they are working. I think they can be easily adapted to a completely GPIO attached LCD.
>> 
>> Regards, Anselm
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