Re: Any idea of minimum safe pixel clock for an 800x600 TFT LCD?

From: Wolfgang Mahringer (yeti201_at_gmx.at)
Date: 04/06/04 

Date: Tue, 06 Apr 2004 13:09:34 +0200

Hi Josh,

Josh Lowe wrote:

> "Don't fix NCLK to "H" or "L" level while the Vdd is supplied. If NCLK
> is fixed to "H" or "L" level for certain period while ENAB is
> supplied, the panel may be damaged".
>
> My concern is that if I use the M16C, and slow down the pixel clock to
> 2 or 4 MHz to free it up somewhat, I risk causing the above damage.
> Given the cost of the panel, I imagine my supervisor could be a mite
> unhappy...

Usually there is minimum refresh rate or pixel clock in the datasheet
for your LCD.

Fixing NCLK: if you stop shifting the bits, the display image isn't
anymore refreshed, a usually black line shows up, because now you have
applied a DC voltage to the LCD panel.
These panel don't like DC voltages at all.
You should avoid stopping the clock for more than a few milliseconds or so.

I have made a project, where a small PIC processor scanned an LCD display.
It scanned "full power" in the main loop to achieve satifactoy refresh
rates. When an interrupt occured, I processed it (just a few ms) and
then continued scanning.
The effect was barely visible on the display.

HTH
Wolf, visiting "down under" soon :-) 

-- 
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Use: wolfgang (dot) mahringer (at) sbg (dot) at

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