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Keypad problem

Rushabh Fegade

I use ATMEL 89c51 microcontroller with keypad 4x4.
My problems is that my 1st row contain 1 2 3 A
it display 1 2 3 A for every row
i checked the code on proteus8 its working fine
and also on 8051 kit its working fine.
but on my PCB its showing 1 2 3 A for every row
in column wise under 1 all are 1 and under 2 all are 2 and so on.
I checked the PCB by interfacing the PCB with 8051 kit's keypad and it worked and then i connected my keypad to the alternate port of 8051 kit it is working well.
but when i connect my keypad directly to the PCB it shows the problem again.What is the solution for it?
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  • 0 in reply to B Reddy

    I checked the PCB by interfacing the PCB with 8051 kit's keypad and it worked and then i connected my keypad to the alternate port of 8051 kit it is working well.
    I GUESS it is not working when you use P0.

    the other ports have "weak" pullup. you - regardless of which port - need pullups on P0 mandatory, on other ports "sluggishness prevention"

    Probably a compiler bug or library bug. Contact IAR support.
    first why a compiler bug (very unlikely), second why contact IAR support when using Keil