The module has 16 output pins and 4 input pins. It is to be soldered with to the back of the 16 x 2 LCD display. It can also be repurposed for other I2C to parallel tasks. board has a PCF8574 I2C chip that converts the I2C data from an MCU into 4-bit parallel data and control bits required by the LCD display.
Features of I2C LCD Module:
Provides I2C to parallel data conversion
Backlight enable jumper
Contrast control potentiometer
0x27 I2C default address. Solder jumper selectable from 0x20 – 0x27
100kHz I2C clock speed
5V operation typical, but also operates at 3.3V.