The Nano converts incoming serial characters to 4-bit codes needed by the LCD. Three non-printable characters are used for special functions (clear screen, backlight on, backlight off)

Hardware - Hitachi comptable 20x4 display - Arduino Nano - FTDI USB-serial - 2n2222 based backlight control

Display - USB-to-serial (FTDI driver) - 20x4 character display - Ascii character set: 32d to 127d - Backlight control

Power: - USB powered - mini-USB connector - ~80mA @5vdc max

Special characters: 0x11 17d == clear LCD display 0x12 18d == set LCD backlight OFF 0x13 19d == set LCD backlight ON