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I'm a total newbie fooling around with a project of mine.

I want to use a MCP23071 I2C port extender (Data sheet) for my arduino project.

The chip has three hardware pins that must be externally biased.

Now, I apologize if the question is silly, but can I just connect the pins to V+ or GND, or do I need to put a resistor in series to limit the current? I looked around a bit but I wasn't able to find an answer.

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Don't forget the reset pin as well as the three address lines, looks like that should be tied high as well. –  PeterJ Aug 24 at 11:40
    
yup, good catch :) thanks, and thanks for fixing the link, too! –  garph0 Aug 24 at 11:51

1 Answer 1

up vote 3 down vote accepted

Yes you can directly connect these pins to GND or V+.

The reason you did not find this explicitly stated is that it is standard that a high-impedance digital input can be connected directly to a logical 0 or 1. When a resistor was needed this would be stated explicitly.

Using a resistor instead of a hard connection might be convenient when you need to change the address on a finished PCB: you can short the pin to the opposite supply rail without damaging anything.

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