Lpc2000

Dear all,

If I am connecting 5V lcd directly with lpc2214, should I common all
the grounds for 5V for LCD supply as well as 3.3V for controller supply.

Pankaj

--- In lpc2000@yahoogroups.com, "Dan Beadle" <dan.beadle@i...> wrote:
>
> Check the IO levels on the LCD and the minimum output high level on the
> 2114.  The odds are good that you can directly connect the LCD to the
> '14 directly with no pull-ups.  For example:
>  
> the VOH min level on the 2148 is V3.3-0.4V or 2.9V MINIMUM...  This is
> the lowest output that the LPC puts out for a standard load high.
> (Usually it will be closer to 3.3V)
>  
> I am using a Lumex display with a Samsung controller.  It has a VIH min
> of 2.2.  Any input above 2.2 is guaranteed to be an input.  Therefore,
> there is 2.9 - 2.2, or .7V of margin on the high side input to the LCD.
>  
> On LOW, there is usually less of an issue.  The LPC will guarantee that
> a zero is below VOL max 0.4V while the Samsung LCD controller requires
> input to be less than 0.6V, leaving a .2V margin.
>  
>  
> As for LCD to LPC... 
>  
> Here the Samsung can output .9 x Vcc or 4.5V max, but guarantees to put
> out at least 2.4V.  The 2.4 is plenty to swing the LPC to high - it
> requires 2.0V or more.  But if the input goes above 3.3V, the "5V
> Tolerant" feature of the LPC kicks in.  I don't know the details, but
> generally, you can think of this as a resistor in series with the input,
> limiting current, and a protection diode that dumps the excessive
> voltage to the 3.3 rail.  
>  
> So.. Bottom line, with this LCD controller, you just wire it up (making
> sure to power the LCD from 5V)
>  
> Hope this helps.
>  
> Dan
>  
> 
>   _____  
> 
> From: lpc2000@yahoogroups.com [mailto:lpc2000@yahoogroups.com] On Behalf
> Of bhimanipankaj
> Sent: Tuesday, November 15, 2005 8:49 PM
> To: lpc2000@yahoogroups.com
> Subject: [lpc2000] LCD interface problem
> 
> 
> Dear ARMieessss..
> 
> thanks for your replies , but my problem is I want to connect a 5V
> interface in traditional way that is 8 data lines and 3 control lines
> with LPC2214, now LPC2214 datasheet is saying that all GPIOs are 5V
> tolerant so I think I can connect the LCD with Pull Ups on GPIO pins
> or can I directly connect the 5V LCD with the port pins.
> 
> Thanks 
> 
> Pankaj  
> 
> 
> 
> 
> 
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