MSP430 (or Arduino) Library for PCF8574 I2C Port Expander – Robert Harder, PhD
PCF8574 IO Expansion Board - Waveshare Wiki
Adafruit PCF8574 I2C GPIO Expander Breakout [STEMMA QT / Qwiic] : ID 5545 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits
PCF8574 I2C I/O Expansion Module - ProtoSupplies
Amazon.com: ALMOCN 10pcs PCF8574 IO Expansion Board I/O Expander I2C-Bus Evaluation Development Module for Arduino Raspberry Pi : Electronics
PCF8574T PCF8574 I2C 8 Bit IO GPIO expander module for Arduino & Raspberry Pi | eBay
Pcf8574 Pcf8574t I/o For I2c Iic Port Interface Support Cascading Extended Module For Arduino Expansion Board High Low Level - Integrated Circuits - AliExpress