Powertip lcd graphic panel

[colin]

Hi
I have one of these wich im driving from a dspic30f
http://www.powertipusa.com/pdf/pg320240c.pdf
but the data sheet leaves a bit to the imagination !
I have a chequor display but wich can only be seen if the scan is reduced to
a crawl
then only one line can be seen at a time,
vee is -27v.
im not sure if the contrast voltage should be 0-5v as other displays or as
some1 suggested on sci.electronics.components
is possibly a negative input ?
anyone have any experience of this make/type of panel ?

thanks
Colin =^.^=

 

[colin]

Hi
I have one of these wich im driving from a dspic30f
http://www.powertipusa.com/pdf/pg320240c.pdf
but the data sheet leaves a bit to the imagination !
I have a chequor display but wich can only be seen if the scan is reduced to
a crawl
then only one line can be seen at a time,
vee is -27v.
im not sure if the contrast voltage should be 0-5v as other displays or as
some1 suggested on sci.electronics.components
is possibly a negative input ?
anyone have any experience of this make/type of panel ?

Well thankfully I got it working a lot better now, thanks to poly' who
sugested the negative contrast voltage wich was indeed the case,
I just fed it -vee through a 1M then 100kR to be safe and it displayed ok.

heres the bit bashing code ..

s=display_text[row/8];
pixels=font8bitmap+(row%8)-font8start*8;
for(col=0;col<no_cols/8;col++)
{
c=*s++;
LCD_CL2=1;
b=pixels[c*8];
D0_D4=b>>4;
b&=0xf;
LCD_CL2=0;
LCD_CL2=1;
D0_D4=b;
LCD_CL2=0;
}
LCD_CL1=1;
if(!row)
LCD_FLM=1;
LCD_CL1=0;
LCD_FLM=0;
if(++row>=no_rows)
{
row=0;
LCD_M^=1;
}


Now I just need a way to avoid making an EL driver transformer with
thousands of turns.

Colin =^.^=

 

[Lostgallifreyan]

Now I just need a way to avoid making an EL driver transformer with
thousands of turns.

Would a trigger transformer for a xenon tube work for that? (I haven't
thought this through, the idea just came to me so I put it forward as it
is).

 

[Don McKenzie]

Well thankfully I got it working a lot better now, thanks to poly' who
sugested the negative contrast voltage wich was indeed the case,
I just fed it -vee through a 1M then 100kR to be safe and it displayed ok.

Out of interest, what -vee level did you need to use?

Don...


--
Don McKenzie
E-Mail Contact Page: http://www.dontronics.com/e-mail.html

Crystal clear, super bright OLED LCD (128x128) for your microcontroller.
Simple serial RX/TX interface. Many memory sizes.
http://www.dontronics-shop.com/product.php?productid=16460

 

[colin]

ok.

Out of interest, what -vee level did you need to use?

about -18v to -22v seems to work ok, depends on the refresh rate etc.

Colin =^.^=

 

[colin]

Would a trigger transformer for a xenon tube work for that? (I haven't
thought this through, the idea just came to me so I put it forward as it
is).

not sure, but the problem is the frequency wich is a bit low +~ 4khz
wich means a lot of turns at 200v to avoid saturation.
trigger transformer probably only expects very short pulses
although I dont know how many turns it has.
needs aprox 3k turns with 12mm^2 ferrite core.

looking around a way to do it seems to exist wich uses a simple switch mode
200vdc generator and simply pulsing it on and off at 4khz. im wondering how
I can combine this with the -20v bias generator.

Colin =^.^=

 

[Lostgallifreyan]

looking around a way to do it seems to exist wich uses a simple switch
mode 200vdc generator and simply pulsing it on and off at 4khz. im
wondering how I can combine this with the -20v bias generator.

The facetious answer would be: "don't" > That negative voltage bias is a
very low-current signal to a sensitive device, it might be asking for
trouble to try to integrate those two systems.

Good idea with the switch mode supply transformer though, far more likely,
and they often turn up free on all kinds of stuff.