This 1602 display module includes an IIC adapter based on PCF8574 chip. This should work nicely on microcontrollers with a limited number of GPIO pins.
Datasheet to the (original) HD44780 driver chip.
How the I2C module is connected to the 1602 LCD display pins. Notice that the I2C adapter will only allow you to use the 4-bit operation mode of the 1602 display.