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Microcontroller › 8051 › 4×4 keypad with 8255
Hi guys,
I'm new to this forum.
I am currently doing my final year school project and i'm finding a difficulty with interfacing a 4×4 matrix keypad with and 8255 port expander (using port C) and all is connected to an 8051 microcontroller.
I'm using C language and everything is working on a simulator (Proteus) but on the hardware side i'm only able to write text on an LCD (ex: Enter Value:) but not from the keypad.
Can anyone help me out pls?
Any tips and ideas on what to look out for, pull up/down resistors etc etc
Thanks.
Maybe I can help you Hi can you email me the project
Email me [email protected]
see you later..
Hi Nicolai,
Ya, that might be due to the absence of pullup/pulldown resistors. Could you please post your circuit also. Also tell me whether you are checking for a high value or low value to detect a key pressed.