Re: [Lcd4linux-devel] WG: USB based hd44780 units ...

[Paul K. <pau...@xs...>]

Hi Michael,

This question did trigger something that was on the back of mind for a 
long time already. Is there a reason why you don't use C++ for 
lcd4linux? That could simplify some of the problems addressed here. 
Besides the structure you created in lcd4linux would map wonderfully to 
an object architecture, and C++ would simplify many coding problems.

Second, what is the current status of the button support in lcd4linux? I 
know it is planned for a long time already. But what are the problems 
with it?

Till, I really like the idea of a $5 DIY USB interface for a HD44780. 
What are you planning on using?

cheers,

Paul

Michael Reinelt wrote:

>Hi Till,
>
>  
>
>>i have a simple question regarding some of the supported usb devices 
>>and their drivers. I am currently building a small and cheap (about 
>>$5 easy to obtain standard parts) diy usb interface for the hd44780.
>>    
>>
>
>Hey, sounds great! My soldering iron is already warming up :-)
>
>  
>
>>I am now wondering why drivers for similar devices (e.g. the BWCT and
>> USBLCD) aren't included into the hd44780. Is there any reason these 
>>devices are not included as interface drivers for the generic 
>>hd44780? This would have the advatage, that all those special case 
>>handlers from this driver would be available to the usb devices as 
>>well.
>>    
>>
>
>Well, you may be right, maybe it would be better to make all HD44780
>stuff into one driver. On the other hand, the drv_HD44780.c file looks
>already complex enough to me :-)
>
>As the "normal" HD4470 driver uses the parallel port (and/or i2c bus),
>there are some other files and libs that have to be linked in (generic
>parport support, ppdev, ...). All the USB-to-HD44780 drivers don't need
>this stuff, but USB support.
>
>Another reason for not merging the drivers is the fact that some drivers
>are maintained by people who own just this specific display and/or
>interface. So modifications won't interfere with other drivers.
>
>If you think of our "embedded customers", who don't compile a 'generic
>LCD4Linux' with all drivers, but prefer a as-small-as-possible
>executable with just one (small) driver included, they would not benefit
>from such a 'generic' driver.
>
>So I'd prefer the situation as it is, with every Interface having its
>own small and simple driver (as long as the interfaces don't have too
>much in common)
>
>  
>
>>I am thinking of making my interface compatible to the bwct (and 
>>perhaps add some more features like e.g. adjustable backlight and one
>>or two input buttons).
>>    
>>
>
>you're right, the BWCT interface has a very nice protocol: it's very
>simple, doesn't have too much own intelligence, but passes through the
>features the HD44780 provides.
>
>adjustable backlight would be cool (but take care of power
>consumption!), keys would be cool, too (although not supported by
>lcd4linux at the moment). If your electronics has some spare outputs (to
>connect a LED or something) or inputs, I'd appreciate that, too.
>
>Please keep me up to date with your electronic design, as I'm really
>very curious :-)
>
>
>bye, Michael
>
>  
>