[Lcdproc] hd44780 display update timing

[Markus Dolze]

-------- Original-Nachricht --------
> Datum: Tue, 23 Dec 2008 15:49:38 +0100
> Von: "Markus Dolze" <bsdfan at nurfuerspam.de>
> An: "LCDproc Mailinglist" <lcdproc at lists.omnipotent.net>
> Betreff: [Lcdproc] hd44780 display update timing

> Hello,
...
> 
> 1. A unmodified hd44780-winamp connected display with no extra delays:
> ====
> HD44780: flushed 32 chars (4 moves) in 0.719918 sec
...
> 
> It would be nice if someone with an hd44780-winamp connected display could
> do the same test on a different OS to see if the slow timing is specific
> to FreeBSD.
> 
> Regards
> Markus

Hi,

today I found the reason why the winamp wiring was so slow on my system: It was the kernel clockrate which I had reduced for some reason.

Compare these:

winamp (delay_nanosleep, kern.hz=100)
HD44780: flushed 32 chars (4 moves) in 0.719908 sec
senddata ~ 20 ms

winamp (delay_gettimeofday, kern.hz=100)
HD44780: flushed 32 chars (4 moves) in 0.002527 sec
senddata ~ 0.060 ms

winamp (delay_nanosleep, kern.hz=1000 (default))
HD44780: flushed 32 chars (4 moves) in 0.071929 sec
sendata ~ 2.2 ms

It is still slower than it could be as seen by switching to 'delay_gettimeofday, but it's fine for me now.

Regards
Markus