Arduino/libraries/hd44780/examples/otherLibraries/Adafruit_LiquidCrystal/README.md

Adafruit_LiquidCrystal hd44780 examples

The Adafruit_LiquidCrystal library must be installed in order to use these sketches.

The examples are broken up into various sub directories.

• 4bit
  Contains example sketches that are for LCDs that are wired up directly to Arduino pins.

• I2C
  Contains example sketches that are for LCDs connected to an Adafruit #292 backpack when using the i2c MCP23008 i/o expander chip to control the LCD.

• SPI
  Contains example sketches that are for LCDs connected to an Adafruit #292 backpack when using the shift register to control the LCD.

Note: that while adafruit uses the term "SPI" the #292 backpack it is not using SPI. It is mearly using a shift register. Also, the Adafruit_liquidCrystal library is not using the SPI h/w but rather simply calling the s/w shiftout() function to do the transfer.