should i connect vee to ground?
what does vee do ?
what happen if i didn't connect it

 

the Vee (pin 3) controls the contrast of the LCD. u should connect it to the ground via a 5K or 10K pot. the pot will control the voltage at this pin. by varying the resistance of the pot you will be varying the voltage at this pin which will in turn vary the contrast of the LCD.

usually directly connecting the Vee pin to ground will suffice. but the contrast will change with changing temperatures so u should include a controlling mechanism i.e. a pot.

and if u are unlucky like me u might get a LCD that requires negative voltage on the Vee pin. i have one which needs at least -6V to turn on. in that case directly connecting the the Vee pin to ground is of no help. ask the person from whom u are buying an LCD about this. and tell him that u dont want an LCD that needs a negative voltage on the Vee pin.

 

The VEE pin on the LCD controls the contrast of the characters on
the LCD. If you short it too groun you will get maximum contrast.

If you get a variable resistor and connect the top end to +supply and the
other end to ground. If you now connect the VEE to the middle pin, you can adjust the contrast with the variable resistor.

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Best Regards