You could also run the I2C scan code that is provided with the IDE, or Nick Gammon's (improved) one; either should find your display. The PCF8574 will be found at addresses 0x20-0x27, while the PCF8574A will be found at Ox38-0x3F.
You could also run the I2C scan code that is provided with the IDE, or Nick Gammon's (improved) one; either should find your display. The PCF8574 will be found at addresses 0x20-0x27, while the PCF8574A will be found at Ox38-0x3F.