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4 x 4 keyboard matrix

 
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steppermotor



Joined: 24 Oct 2010
Posts: 10

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4 x 4 keyboard matrix
PostPosted: Fri Oct 29, 2010 6:35 pm     Reply with quote
I'm trying to interface a 4x4 keyboard matrix to a PIC16F877A, I was wondering does anyone know which pins on this keypad are the row and which are the columns the data sheet is unclear about this.

http://datasheet.octopart.com/96BB2-006-F-Grayhill-datasheet-46283.pdf
PCM programmer



Joined: 06 Sep 2003
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PostPosted: Fri Oct 29, 2010 8:07 pm     Reply with quote
Looking at the back of the keypad, the pins are numbered like this:
Code:

8 7 6 5 4 3 2 1

These are the pin assignments:
Code:

Pin   Function 
 1    Row 1
 2    Row 2
 3    Row 3
 4    Row 4
 5    Col 1
 6    Col 2
 7    Col 3
 8    Col 4

Remember to put 10K pullup resistors on the Row pins.
John P



Joined: 17 Sep 2003
Posts: 331

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PostPosted: Sat Oct 30, 2010 11:18 am     Reply with quote
Unless you use Port B and have the internal pullups enabled.
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