Arduino Uno with Logger Shield (Adafruit #243) and MCP23017

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dcgonzal
 
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Arduino Uno with Logger Shield (Adafruit #243) and MCP23017

Post by dcgonzal »

Hello,

I am starting a project where I will be using a Logger Shield (Adafruit part #243) and an MCP23017 to expand the inputs and outputs. From the MCP23017 I will wire A0 to 5V and A1,A2 to Ground (because the RTC is using address 000 correct? Thus requiring me to address the MCP23017 at 0x21). Also, I was wondering, all the recommendations I have seen for the wiring from the SCL, SDA to A5,A4, respectively, they have a 4.7KOhm resistor going to 5V. However, in the Logger Shield schematic I see that they are using 2.2KOhm resistors to 5V. Should I just use the 2.2KOhm and not install the 4.7KOhm resistors? Will the MCP23017 work ok under these conditions?

Thank you for any help.

David

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Franklin97355
 
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Re: Arduino Uno with Logger Shield (Adafruit #243) and MCP23017

Post by Franklin97355 »

If the lines are already pulled high you should not need the resistors.

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