4x4 keypad question on pulldown resistors

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HommerSimpson

New Member

• Jun 15, 2011

• #1

Im making a 4x4 keypad out of an old remote. Should I put pull down resistors on it or is this something that some chips need and some dont ? Very New to all this.
Thanks Greg

 

J

john blue

Member

• Jun 15, 2011

• #2

you need to pull it down or up to make sure that the 4x4 keypad logic is not floating

 

Ian Rogers

User Extraordinaire

Forum Supporter

Most Helpful Member

• Jun 16, 2011

• #3

What are you connecting it to. If it's a pic.. most people use portb and set weak pullups.

 

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stephen87

New Member

• Jun 16, 2011

• #4

if you are using the following configuration of 4x4 keypad - **broken link removed** - there is no need of pull up/down resistors since the pins are all connected to the microcontroller.

 

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HommerSimpson

New Member

• Jun 16, 2011

• #5

right now im connecting to a at89c51. But in the future it will be PIC chips... I still have to order some.. just got pickit 3 in mail... so im playing with parts and peaces & making things..

 

Ian Rogers

User Extraordinaire

Forum Supporter

Most Helpful Member

• Jun 16, 2011

• #6

Then as myself and stephen said .. no need for resistors... low nibble inputs, high nibble outputs...

 

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HommerSimpson

New Member

• Jun 16, 2011

• #7

Thanks IAN..I will post how it goes.... :}