Re: [lcd4linux] Re: Everbouquet 44780 modules

[Aragon G. <ar...@ph...>]

A high quality photo of my module's controller board is available at:

http://decoder.geek.sh/misc/mc2004E.jpg

The interesting component pads are:

R11
Q1
R9
R10

The leftmost pad of Q1 leads through R11 and then into one of the 44780
chips.  This must be the base.  Voltage between that line and ground is
about 2.5V after 44780 initialisation.

The topmost pad of Q1 connects to pin15 on the connector (LED+).

The rightmost pad of Q1 connects to the LED Anode via R9/R10.

The jumper on R7 would need to be desoldered before attaching this extra
circuitry.  If R7 is left in place, the backlight will come on and stay on
whenever power is applied to LED+.

With the extra circuitry in place and R7 removed, the backlight will only
come on when Q1's output is HIGH, and LED+ has power.

Now the question is.. how do you tell the 44780 to set Q1 high!?

So far I've tried sending this data in instruction mode (RS low):

  1xx11
  1xx01
  1xx10

and:

  1xxx11

  x = appropriate value for my interface/cursor settings


No luck.  Voltage at R11 stays 2.5V.

Any ideas? :)


Regards,
Aragon


| By Aragon Gouveia <ar...@ph...>
|                                          [ 2004-02-16 10:29 +0200 ]
> I'll try take a photo of it tonight.
> 
> I can trace the track going into one of the silicon chips embedded on the
> controller board, but that's it.  It also jumps through to the otherside of
> the board, but can't trace it there (without breaking my module).
> 
> Before I went to bed last night I checked the voltage between the base pad
> and ground - ~2.7V before 44780 initialisation, ~2.5V after initialisation.
> 
> I'm going to hack up someone's source code tonight hopefully and see what
> happens if I play with the two "unused" bits (D1 and D0) of the Set
> Interface Length and Move Cursor commands. ;)