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lcd display weird problem!

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anasimtiaz

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hi ppl....i just wanna discuss this problem im facing rite now...i made a circuit on a breadboard which included a LCD display (16x2) and it worked perfectly with some effort...as the circuit gre bigger (other components were added) the breadboard got a mess so i decided to make a new circuit neatly while retaining this old one..now in the new and neat circuit i hv checked all connections (continuity of the board as well) but my lcd display is not working for some weird reason! everythign is same!! EXCEPT that ive changed the data ports from P1 in earlier cct to P2 here and control lines from port 3 to port 0 pins here...now does that really matter???
 

ofcourse it doesnt matter
but let me tell you something maybe you have forgetten:

•be sure that you have connected P2.0 of the microcontroller to d0 of LCD, and P2.1 to d1 etc....
because maybe you have connected P2.7 to d0,so LCD will not work

•did you change the old progam of the microcontroller to be suitable for the new ports

•if you use 8051 microcontroller dont forget to put pull up resistors on P0 (because P0 doesnt have internal pull up resistors )
 

yeah ive checked abt the data lines with the port lines and ive changed the program as well....but im not sure abt the third point....im using atmel 89c51, do i need to put the pull ups ???

thanks
 

Since Port 0 has an open drain, when 1’s are written to it, its outputs float ..
Therefore external pull-ups are required for the pins of P0 ..

Regards,
IanP
 

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    anasimtiaz

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