lcd based voting machine using 8051

[praisethelord]

Sir,

i have done stimulation in proteus successfully….and is doing the circuit in bread board…………but i’m not getting the output…..the lcd is on…….cursor just moves in the display………….when the 10 k pot is varied …..lcd dislay blocks……just help me out……its urgent…..i have not used preset as it is not given in the circuit diagram……please help………..

[doraemon]

When lcd is not properly initialized it display blocks. Check connection between lcd and 8051 pins is properly done. If lcd connections are proper then check 8051 reset circuit is proper and 8051 executing instructions.

[praisethelord]

sir how can check reset circuit of 8051……………..Also what is need of preset switch………..it is not given in the circuit diagram 

[doraemon]

connect one wire to pin no 9 that is RESET pin second end of wire keep open. give circuit 5v supply then touch second end of wire to positive supply and remove. If you have a multimeter check voltage across pin no 40(Vcc) and 20(Gnd) is about 5V. Preset is one type of variable resistor that is used to adjaus contrast by changing voltage of pin no 3 of lcd. If you dont want to use preset then just ground pin no 3 of lcd. IF still your circuit dont work post picture of circuit you made.

[Author]

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