AN1447 is a technical application note that describes how to use ST62 MCU to drive a 4-multiplexed LCD. This technique is suitable for applications that require low-cost small displays, while also taking advantage of the ST62 MCU's multi-functionality.
The document details the principles of driving Liquid Crystal Displays (LCDs), covering both direct drive and 4-multiplexing methods. It explains the electrical requirements, such as voltage levels and frequency ranges, necessary to ensure proper display operation and longevity.
A software library written in MAST6 assembly language is provided to implement a solution where a standard ST62 microcontroller directly drives the LCD. The note includes guidelines for customizing the library, defining I/O resources, and managing timing to combine LCD driving with other application tasks.
The implementation requires only 8 additional resistors.
The driving frequency must typically be under 2000 Hz.
The backplanes require voltage levels of 0, Vpp/2, and Vpp.