PCF8574 I2C GPIO Expander Breakout - Stemma QT/Qwiic Ada 5545

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Amazon.com PCF8574 I2C GPIO Expander Breakout - Stemma QT/Qwiic Ada 5545	$11.99	Delivery date & cost shown at checkout

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11.99
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PCF8574 I2C GPIO Expander Breakout - Stemma QT/Qwiic Ada 5545
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15.52
eBay
Adafruit Pcf8574 I2c Gpio Expander Breakout, Stemma Qt / Qwiic, 5545
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4.95
DigiKey
Adafruit Industries LLC 5545 STEMMA QT I2C 8 GPIO PCF8574
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4.95
Adafruit Industries
adafruit-Adafruit PCF8574 I2C GPIO Expander Breakout
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Product Details

It has 8 I/O pins

Three I2C address select jumpers mean up to 8 expanders to one bus for 64 total GPIO added

Each pin can be an input with light pull-up or an output sink

IRQ output will automatically alert you when input pins change value

This chip does not have a pin direction register. You cannot set the pins to be input or output - instead each pin has two possible states. Basically you can think of it as an open-drain output with a 100K resistor pull-up built in.

Option one: Lightly pulled up 'input' - by default it will read as a high logic level, but connecting the GPIO to ground will cause it to read as a low logic level.

Option two: Strong 20mA low-driving transistor sink output. This means the output is 'forced' to be low and will always read as a low logic level.