I started a project using a standard HD44780 display, wired to an Arduino UNO. That, of course, exhausted a full seven data lines, which in the course of the development, left me short of UNO pins to do all other desired tasks. So I bought an LCD display with an I2C module attached, and, after some library confusion, I got it working. It worked with a library said to be for 1602 LCD's.
So here's my question. I have a number of previously purchased HD44780 displays, and, to be compatible with my library, I want to buy just the 1602- compatible I2C modules to solder to the LCD's. The LCD's I own now do have an apparent model number on the back, but nothing about 1602.
So, what is 1602, and how do I ascertain compatabilty of an HD44780 LCD with this 1602 standard?
Thanks in advance for any assistance.