The 20 x 4 LCD comes with a I2C backpack. I know it has A0, A1, A2 to set the address, as shown at the bottom here: https://tronixlabs.com.au/news/tutorial-serial-i2c-backpack-for-hd44780compatible-lcd-modules-with-arduino/
It points to here: http://www.nxp.com/products/interface-and-connectivity/interface-and-system-management/i2c-bus-portfolio/i2c-general-purpose-i-o/remote-8-bit-i-o-expander-for-icbus-with-interrupt:PCF8574_74A
My unit shows up as 0x3F.
And even with all this information I can't tell how to change it.
I need to have a second display on the same I2C bus.
Question: How do I change the address of the second one?