Re: [Lcd4linux-devel] Patch for multiple displays

[Michael R. <re...@eu...>]

Hi Stefan,

> here's the patch:
> ---------------------------
> --- drv_HD44780.c       2007-06-05 23:07:08.000000000 +0200
> +++ drv_HD44780_new.c   2007-06-05 23:15:24.000000000 +0200
> @@ -843,8 +843,9 @@
>             currController = (1 << controller);
>             break;
>         }
> -       row -= CROWS[controller];
>      }
> +    for (pos = 0; pos < controller; pos++)
> +       row -= CROWS[pos];
> 
>      /* column outside of current display's width */
>      if (col >= CCOLS[controller])
> 
> ---------------------------


Are you *really* sure about this? Without trying, just by looking at the 
code, I guess your patch is wrong. You would decrement 'row' two times...

> I didn't solve the problem with the control signals, i have to ask why
> there are restrictions how they are wired.
> For example, he has four displays and wants to set the four enable lines
> to DB4-DB7 and STROBE + RS to the control signals..

The restriction comes from the fact that control and data signals share 
the same bits (signals are 8 bit wide), If I allow them to get mixed, 
I'd have to resize the data type to 16 bit, and declare the lower 8 as 
data lines and the upper 8 as control lines. This would require massive 
rewrite of the parport abstraction layer, and probably a rewrite of all 
parport drivers.


bye, Michael

-- 
Michael Reinelt <re...@eu...>
http://home.pages.at/reinelt
GPG-Key 0xDF13BA50
ICQ #288386781