HT1650 is a peripheral device specially designed for I/O type MCUs which are used to expand the display capability.The max. display segment of the device are 2048 patterns (64 segments and 32 commons). It also supports four data bits interface, buzzer sound, Watchdog Timer or time base timer functions. The HT1650 is a memory mapping and multi-function LCD controller. It can control TN-type (Twisted Nematic) or STN-type (Super Twisted Nematic) LCDs. The software configuration feature of the HT1650 make it suitable for multiple LCD applications including LCD modules and display subsystems. Only six lines (CS, WR, DB0~DB3) are required for the interface between the host controller and the HT1650.