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Hello,

I have a matrix keypad from eos that I want to interface with Arduino.

My question: can we declare 4 digital output pins and 3 digital input pins and directly wire them without any resistors and pull up's ? (4 columns and 3 rows of the keypad matrix - it as no common point - which will be interrogated putting one column HIGH, reding the 3 row, next... loop).

I have done the test and an ouptut pin can be wired directly to an input pin, but doesn't it take too much power ? (TTL provide against that and enable direct digital interconection between logic circuits... and, also, Atmel has incorporated pull up resistor for each output digital pins.).

So, on benchtests... it works... but I am afraid to burnit latter....

Somebody can answer ? Thank's !

Pierre.