For my first "real" project I would need 2 lcd modules 20x4 characters.A lcd module that would match my needs would be the sainsmart 20x4 I2C lcd module. The specs mention "I2C Address: 0x3F or 0x27". So, is the adress changable of do you have one or the other? If I buy 2 of these, can I allways use both of them?
I would like to start with 2 lcd modules and maybe later when required expand to 4.
Then you're likely going to have problems with I2C addresses if you want that on a single Arduino/I2C bus.
Aren't those I2C backpacks basically a PCF8574 on custom PCB? Then you'd have a choice of 8 I2C addresses.
I don't see any user accessable solder pads on the Sainsmart backpack.Setting the address could involve scratching off the protective paint and re-routing traces.Leo..