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[lcdproc] HD44780 Display corruption Problems


Chronological Thread 
  • From: benjamin_tse AT agilent.com (TSE,BENJAMIN (A-Australia,ex1))
  • Subject: [lcdproc] HD44780 Display corruption Problems
  • Date: Thu, 28 Jun 2001 16:23:56 +0900

Hi Tracy,

There are a few things that you can try:

1 - Change the delay mechanism. In hd44780.c modify the following snippet of
code as per the comment:

// Uncomment one of the lines below to select your desired delay
generation
// mechanism. If both defines are commented, the original I/O read
timing
// loop is used. Using DELAY_NANOSLEEP seems to provide the best
performance.
//#define DELAY_GETTIMEOFDAY
#define DELAY_NANOSLEEP

2 - If this doesn't work, try adding some delays to the
lcdwinamp_HD44780_senddata function in hd44780-winamp.c. i.e. add calls such
as

hd44780_functions->uPause(10);

between the calls to port_out.

3 - If that doesn't work, increase the number you've tweaked even more :-).

Ideally, most of this functionality should be accessible from the command
line .... :-)

The problem you see arises because each display has slightly different
characteristics. The default delay timing appears to work for most people's
displays but there are bound to be some that work with different timings. It
also doesn't help that some of the code relys on ISA bus timings!

Hope it helps,
Ben

> After about 5 minutes or so, the display will start to
> corrupt, lines 1 and
> three will be out of alignment by 1 or 2 spaces with lines 2
> and 4. after
> about 2 more minutes, the display will just begin displaying garbage
> characters. I can correct the problem just by running the LCDd command
> again. This display works fine on a windows pc using the
> winamp plugin.
> I have tried adjusting the upause(40) value to about 66 (info from a
> previous post to the lcdproc mailing list), to no avail. The
> display still
> corrupts, but later then it did before/
>
> Any suggestions?


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