Hitachi type LCDs are fairly old technology.  Even newer clones faithfully
copy the original timing specifications - which are VERY exacting.

At startup you either have to have the voltage powering the display rise at
a very exact rate, or . . .

Wait until after the chip should have initiallized, then hit it with 3
resets in a row, with the correct pauses for each reset command to be
executed.  After the 3 'reset to 8bit, normal cursor and movement
directions' commands (0x30) you then should set your desired mode(s), turn
off then turn on the display and clear & home the display.  This all takes
less than half a second and ensures a consistent startup.

Bye.

-----Original Message-----
From: Jeff DeMaagd [mailto:jeff@DEMAAGD.COM]
Sent: Thursday, 1 November 2001 8:29
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]: LCD panel init problems


I have a 2x20 character LCD panel that doesn't seem to want to init properly
on some power-ups.  We do have it and some 4x4 capacitive keypad circuitry
connected to the main board by a fairly scandard type 6" / 15cm long ribbon
cable.  Sometimes it powers up and inits properly, sometimes it displays
garbage.  Once it starts fine, it runs fine until shutdown.  Once garbage,
always garbage until shutdown.  A power cycling might change the situation,
but that is not guaranteed.

Should I try to add some a big bypass cap or check something else?  All the
ICs and the panel seems
to be properly bypassed to me.  I have also tried the power-up timer on the
PIC too, with little change.

Any general recommendations?  Thanks!

Jeff

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http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.