More investigations:
I am able to change contrast from original device, but I don't observe any voltage drop in any of the power or other pins. Does this mean that contrast could be sent as a command not as a separate pin input?
As I don't have oscilloscope (I am considering to get it if it would help), I used simple voltage tester, while display was powered in original device:
PC0/A0 =
0 - 0.01V (fluctuates from - to)
PF1/UCAS/IRQ14 =
3.27V (seems to be same as display power)
PF4/HWR =
3.26 - 3.27V (fluctuates from - to)
OE1 =
0.71 - 0.74V (fluctuates from - to)
Also I have over viewed these display drivers:
KS0108 - seems to be 5V power and does not have contrast command.
**broken link removed** - possible to power 3.3V and has contrast command, also can drive second slave display -
possible candidate?
S6B0724 - possible to power 3.3V and has contrast command, also can drive second slave display -
possible candidate?
sed1335 - seems to be 3.5V-5V? power and does not have contrast command, also can drive second slave display.
SED1520 - seems to be 5V? power and does not have contrast command. Can drive second slave display though.
SED1530 - seems to be 3.3 (SED1531) -5V? and has contrast command, also can drive second slave display -
possible candidate? (Optrex 323 display also uses this)
Any other I should look into? Any other thoughts?