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I'm designing a PCB that uses Analog Devices' MAX7301AAX GPIO Expander IC to expand the Raspberry PI's GPIOs.

Digikey MAX7301

The reason I'm using this IC is that my application requires a lot of output pins for SPI's CHIP SELECT and digital switches to output HIGH/LOW.

For example: P4 to P14, each pin is a Chip Select to enable an device through SPI; and P15 to P25, each pin is able to output HIGH(>2V) or LOW(<0.8V) to control digital switches ON/OFF. fig-2

I have a few concerns that can't find answers from the datasheet:

  1. Can these GPIOs pins(p4-p31) have multiple pins outputing HIGH(V>2.0V) at the same time to turn on multiple switches at the same time? ex. p5,p7,p9,p11 output HIGH at the same time.

  2. Will input a new command reset the previous command? ex. first set p5,p7,p9,p11 as HIGH, will a new command for p28 reset previous pins' status? In other words, does each pin act as an independent GPIO and does not intefer with other pin's commands?

Thank you for your answers!

enter image description here

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1 Answer 1

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The datasheet says:

The MAX7301 ... provides microprocessors with up to 28 ports. Each port is individually user configurable to either a logic input or logic output. Each port can be configured either as a push-pull logic output capable of sinking 10mA and sourcing 4.5mA, or a Schmitt logic input with optional internal pullup.

It does not mention any additional restrictions, except for the total sink current.

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