Keypad on portA 18f1220

[be80be]

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.

 

[Pommie]

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.

 

[be80be]

thanks Mike