HELP: 16 X 2 lcd interfacing not woking with at89c52

hi,

i am a newbie in this forum, as well as in electronics project. i have been working in a digi-lock project, the source of which has been taken from http://www.engineersgarage.com/micr...code-lock-with-password-using-at89c51-circuit.

i am using at89c52 microcontroller. the problem im facing here is I can't make the lcd display working. ive tried with the simplest ones, but nothing is showing in the lcd.

Supply in the microcontroller seems above 5 volt without joining the lcd, but below 5 volt while joining the lcd. im wondering if the voltage drop is causing for the problem with the lcd?

im really confused and disappointed already.

pls help me....plssssssssssss

I would recommend double check the pinout of your lcd module with the datasheet,and sure the connection is right. Pay more attention on pin order and contrast pin requirement.
if lcd module's back light is turned on ,voltage may or may not change a little bit according to your power supply quality.

Check the contrast voltage trimpot adjustment!