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i want the circuit diagram for 4*4 keypad interfacing with P89V51RD2 for my project.
go for thz links it might help you, the pin config. for at89c51 and p89v51rd2 is same
hi, i'm actually using a 4x4 keypad...but den i thought d c code in d links u provided might work out, but wen i did, its really not working, d lcd is showing d values randomly (i.e. without any keypress)...plz hlp me
if the LCD is showing results without pressing any key on key board???
1) what exactly the key interfacing type you using... R u sing the same key pad which is shown in the ckt.... or providing an extra ground or Vcc in the keypad ckt....
2) check out if there is any short connection that might causing you that problem..
3) random key means? does the LCD shows one or more key with a continuous sequence or there is no sequence...
4) have you pressed any key and check weather it is showing that key on LCD or not????
check those things and let me know...
check the power supply
if u are using and adaptor then change te adaptor and see if the numbers are already dispalying without any key is pressed
keypad is connected with PO..
PO needs PULL UP resistor ..
use 10K pull up resistor and ur problem will be solved.
here the code is for 4*3 keypad . but u can modify it easily ...
i already posted a diagram named CODE LOCK..
you can see that diagram , hope it will solve ur problem .,.
use a debounce condition in coding
For more designs, check out TI Reference Design Library
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