How to scan the keypad for the key input?

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phongle119

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keypad

Any one know how to scan the keypad for the key input?
Thanks
 

Re: keypad

Let say you have 4 by 4 row and column keypad and wanna scan it.

You need to pull either the column or row high with a 2k resistor .
Then the remaining row or collum is get scan for the low signal. From that we can figure out which key is being press
 

    phongle119

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Re: keypad

Here you can find an example of hex keypad scanned by a PIC:
https://ww1.microchip.com/downloads/en/AppNotes/00529e.pdf
The same principles will apply to ony other microcontroller ..

Also, have a look at this example:
**broken link removed**
It uses only single microcontroller pin ..

Regards,
IanP
 

keypad

Hi,

Here is a full circuit and source code.
**broken link removed**

Click "Helped me" if you found my answer useful.

Good luck.
 

Re: keypad

you may find asm code for 8051 frome book ' The 8051 ...." , was upload at 'EDA upload/download'.

or refer these links






you can find more with search at "microcontroller'
 

Re: keypad

read scott mackenzie "8051 u C"
 

Re: keypad

also chek 8051 uC and embedded systems by mazidi.

and let me give u a hint for a simpler technique

connect the whole 8 wires of keypad at one port.
the wires of rows at one nibble and that of cols at other.
then first send 0x0f and scan the port and then 0xf0 and scan the port. then logically OR the two results. thats ur code. really. only do the same process after giving a little delay(loop delay) for deboiuncing
 

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