This I2C to parallel adapter fits right on the back of 12864 graphic displays with the very popular KS0108 controller, and also on any character display 1×8 to 4×40.
8 of these modules can be operating parallel on the same I2C bus, due to the on-board address selection.
The MCP23017 is a very capable chip, with programmable pull-up resistors, interrupt handling, and many other features.
The MCP32017 display adapter module can also be used as GPIO port extender for any other application. Most interesting is the fact, that it can deliver 25mA on every GPIO pin. This is a lot more than most port expander chips have to offer.
There are very good instructions for example on Youtube, how to use this module. And there is a library for Arduino on Github, making it super easy to add this module to your Arduino project.
– Operating Voltage 1.8 to 5.5V
– Operating Temperature -40 to 125 C
– Interface IC
– Max. Bus Frequency 1700 kBits/s
Note: Don’t make the mistake and use this adapter to adapt displays with ST7920 controller to the I2C bus. The ST7920 comes with a native SPI mode, and it just does not make sense to add a bit-bang mode to a device what already comes with an easy to use serial interface (SPI in this case).