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Help on Hitachi LMG7420PLFC-X
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Author:  ykhuang21 [ Mon Mar 28, 2005 11:48 ]
Post subject:  Help on Hitachi LMG7420PLFC-X
I have just got a Hitachi LMG7420PLFC-X Graphic LCD but I have trouble trying to get it wired up. I am wondering whether I need an inverter to operate the LCD.

http://www.baso.no/content/pdf/LMG7420PLFC-X.pdf
Author:  coorz [ Mon Mar 28, 2005 12:13 ]
Post subject: 
Looks like you need an inverter for the CCFL backlight and also a negative voltage supply (Vee) for the contrast adjustment.
Author:  ykhuang21 [ Tue Mar 29, 2005 3:09 ]
Post subject: 
Yar, I have connected the pins as the following

VSS - GND
VDD - (+5V)
VO - (-10.8V)
/WR - P2.6
/RD - P2.5
D0-7 - P1
/EN - P2.7
C/D - P2.4
/RET - P2.3


I would need to program it using a 8051 microcontroller. My school have not bought the inverter, so in the meantime my lecturer actually said that it may or may not work with an inverter. But after making all the connections nothing came out, so I was wondering is it because of the inverter or is it because of my connection problem.
Author:  Henri [ Sun Apr 03, 2005 11:11 ]
Post subject: 
Depending of the lcd (especially with transmissive lcds) it might be difficult to see if there's no backlight powered. But with some external light it should be possible to see something and verify the display is working.

So you have the negative voltage to the VO pin ? Can you see the contrast changing if you adjust this negative voltage ? This would be the first thing to verify before trying to write data to the display.

The display has a T6963C controller I suppose ?
You can find some T6963C code here: http://forum.lcdinfo.com/viewtopic.php?t=362
Author:  ykhuang21 [ Fri Apr 08, 2005 11:17 ]
Post subject: 
I have managed to get so display onto the LCD. But I cannot seems to be able to plot pixel by pixel. I have found this code on the net but I do not know how to translate it to assembly language.

Procedure lcd_setpixel(column,row) ; // set single pixel in 240x128 array
addr = #G_BASE + (row*#BYTES_PER_ROW) + (column/6) ; // memory address of byte containing pixel to write
dput(addr % 256): dput(addr >> 8): cput($24); // set LCD addr. pointer
cput($F8 | (5-(column % 6)) ); // set bit-within-byte command
EndProcedure
Author:  ykhuang21 [ Mon Apr 11, 2005 8:38 ]
Post subject: 
I have just notice that I was actually plotting my graph using the cursor, that's why I cannot get a nice graph that stays on the screen. Anyone knows how to plot a graph pixel by pixel instead? Please help~
Author:  swimmel [ Thu Apr 06, 2006 20:46 ]
Post subject:  Re: Help on Hitachi LMG7420PLFC-X
ykhuang21 wrote:
I have just got a Hitachi LMG7420PLFC-X Graphic LCD but I have trouble trying to get it wired up. I am wondering whether I need an inverter to operate the LCD.

http://www.baso.no/content/pdf/LMG7420PLFC-X.pdf

hi,
I have also purchased this display from baso but I cant get it to work. I have wired it correctly, this is all I get up on the display:
Image
Image

any ideas?
have tried:

lcdstudio, lcdhype and lcd4linux
:D
Author:  Torro [ Sun Apr 09, 2006 21:08 ]
Post subject: 
ykhuang21 wrote:
Yar, I have connected the pins as the following

VSS - GND
VDD - (+5V)
VO - (-10.8V)
/WR - P2.6
/RD - P2.5
D0-7 - P1
/EN - P2.7
C/D - P2.4
/RET - P2.3


I would need to program it using a 8051 microcontroller. My school have not bought the inverter, so in the meantime my lecturer actually said that it may or may not work with an inverter. But after making all the connections nothing came out, so I was wondering is it because of the inverter or is it because of my connection problem.



I was just wondering about this, V0 - VEE. Should the -15v? be connected to VO and let VEE be unconnected?


And to get 6x8 font size, could I put +5v at pin 19 to swap the standard 8x8 font size?
Author:  coorz [ Sun Apr 09, 2006 21:47 ]
Post subject: 
Swimmel: i'd suggest you rewire and check the connections with a multimeter; it looks really bad

Torro: if your LCD has onboard Vee then wire it up with a potmeter over Vo and GROUND as you can see in this schematic.
I believe this Hitachi display has been discussed before here with a proper wiring scheme too, use the search!

Font selection is done by putting your FS pin either high (+5) or low (GROUND)
Author:  Torro [ Sun Apr 09, 2006 23:08 ]
Post subject: 
Okey, I am getting a bit confused. The schematics on those t6963c controllers are very similar, but have a few differences. The DATAVISION panel is similar to this Hitachi, it is also lacking a dc-dc neg. generator.

Is it really as easy as this schematic from liquid-mp shows, just a pot between ground, VEE and V0?

+5v on pin 19 seems correct, and a bit easier than wiring the controller chip. Thank you for taking your time.
Author:  coorz [ Sun Apr 09, 2006 23:26 ]
Post subject: 
Yes it's that easy, but if there's no onboard DC then look at this schematic and follow that Vo and Vee (Vlc) scheme.
Maybe as you suggested you can feed the -15 directly into Vo but contrast might not be optimal/correct.
Author:  Torro [ Sun Apr 09, 2006 23:40 ]
Post subject: 
Image

This is the reason why I have trouble to get those schematics around. It is from the specs. on this panel, and shows a different story.

Edit: Finally found it: Must be like this one: (Thank you Henry)
Image
Author:  swimmel [ Sun Apr 30, 2006 13:51 ]
Post subject: 
coorz wrote:
Swimmel: i'd suggest you rewire and check the connections with a multimeter; it looks really bad

hi, I have checked my connection with a multimeter and all they are all connected.
On the backside I have soldered where it is circuits.

I still cant get any text or picture up on the display.

is there any foolproof method to check if the display works?
Author:  swimmel [ Sat May 20, 2006 15:42 ]
Post subject:  LMG7420PLFC-X
is there anyone who have actually got this display to work.?
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