Em 3/5/2010 10:41, ivp escreveu:
>> Others are telling you about the Vlcd pin. This is to bias the LCD
>> backplane itself. They are warning you that this pin should not be
>> left unconnected. It should be tied to ground through a low value
>> (about 330 to 2K ohms) resistor.
>>     =

> Most LCD datasheets show a 5k or 10k pot connected between
> Vcc and Vss with its wiper to Vo (contrast pin). In practise, that's
> a waste of time. The simplest way is to wire Vo straight to Vss, but
> the best contrast I've found generally is to have Vo a touch above
> Vss. For this I use a 47R between Vo and Vss, and a 4k7 between
> Vo and Vcc. With Vo unconnected it sits way above the maximum
> contrast voltage for any degree of readability
>   =



For most LCDs I use, 0V at Vo gives a completely black image, it is
usually possible to see something by looking at a very shallow angle.

When I don't use PWM-generated contrast, I use a 10K pot in series with
pin Vo to ground, one end of the pot is left open to save some micro-amps.


Regards,

Isaac

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