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Keypad on portA 18f1220

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be80be

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Seeing there is no weak pullups on portA of a 18f1220
So would it be a good ideal to pullup the columns with say a 20k resistor.
So that when you press a key it will go low.
 

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Pommie

Well-Known Member
Most Helpful Member
Yes, you need pullups on either your rows or columns. You don't need (mustn't have) the pull downs as the way you read the pad is by making 1 pin an output and setting it low. I.E. if you make A0 output and low then A3, 6 & 7 will be low if the top line of switches were pressed. A1 will give the next row and so on.

Mike.
 
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