Connecting up the MCP23S17 and HD44780U based LCD Ever wondered how to hook up an LCD display with your Raspberry Pi without using up all your GPIO pins? With the right tools, such as the MCP23S17 and wiringPi, you can effortlessly keep your I2C, UART, and SPI functionalities free for other worthwhile endeavors. This blog post truly proves that the GPIO is quite flexible with the I2C or SPI pins and setting up the MCP23S17 is as simple as connecting the pins. And with support for 5v LCD modules, I can assure you that this setup is definitely lit! 11 May 2014