[lcd4linux] Re: LCD4Linux Bug... or a Computter bug =))

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

Hi Xavier,

> I was using my 20x4 HD44780 On my Dual Pentium 3 with LCDProc..
> I never seen a glitche in the screen... But I transfered to my 
> Pentium II 233 Mhz and now in lcdproc I get glitched character
> all the time.. In your prog that sligly less frequent.. I only get
> them if I overuse the cpu...
> 
> I don't know if you see where is the bug ( my first tough was that
> my box lock down sometime ant the update of the lcd is'nt done at the
> right time.. )

I've never seen such an error because of a slow CPU. All the timing 
stuff are "minimal" timings, so it should not matter wether it takes 
longer...

B ut there may be another issue: Most of the parallel port display use 
+5V for logical "high", some parallel port deliver only 3.3V. This may 
lead to misinterpretation and glitches. I've had this with T6963, and 
developed a circuit which does level shifting (quite complicated, 
because the T6963 needs to read from the parallel port, too)

Do you own a multimeter? Can you check wether the old and the new 
parport deliver 3.3 or 5V?


bye, Michael

-- 
Michael Reinelt                                   Tel: +43 676 3079941
Geisslergasse 4                                   Fax: +43 316  692343
A-8045 Graz, Austria                          e-mail: re...@eu...