I've been trying out a few Optrex displays given to me
yesterday, and found some that are a little different

http://home.clear.net.nz/pages/joecolquitt/optrex.html

Marked PJAD112ZC PWB-15164C and has a single
Oki M6222B interface/driver (very similar to the HD44780)
date coded 8920. The knob is the contrast control

The thing is, although the data sheet for the M6222B
says it's capable of a 16x1 display, this 'un has 15
alphanumeric positions and 3 x 7-segment characters
starting where you'd expect address 0x0f. As you can
see from the picture, 0x00 to 0x0e are readily accessible,
but what's the deal with the other 3 positions ? I can write
to address 0x0f, but I can't make sense of whatever
appears. Sometimes you get recognisable characters
in 0x0f, "0x10 & 0x11", sometimes not, sometimes blank.
I didn't specifically program it to display " P1"

Perhaps the 15164 is a clue ? 15 ? 16 ?

I could use them for just the predictable 15 characters but
would like to know if those other three are in fact useable

TIA

(btw, before I work on an LCD I ALWAYS put a piece of
acrylic over it. I dropped a screwdriver on an LCD once.
Just once, never again. Homey don't play that game no
more)

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