This note describes a technique for driving Liquid Crystal Displays (LCD) with any standard ST7 Microcontroller (MCU) i.e without any specific on-chip LCD driver hardware. This technique offers a solution for applications which require a display at low cost together with the versatile capabilities of the standard ST7 MCUs. This note also provides a technique to control the LCD contrast through software.
This document details a low-cost method for controlling Liquid Crystal Displays (LCDs) using any standard ST7 Microcontroller. It explains how to drive LCDs in single, duplex, and quadruplex modes using only standard I/O ports and one timer, eliminating the need for specific on-chip LCD driver hardware.
The note provides techniques for generating necessary waveforms, calculating contrast levels through software, and managing power consumption. Additionally, it includes an overview of a demo board based on the ST72F321B microcontroller, featuring schematics and programming instructions to help users develop and test their applications.
| CPU load required for controlling the LCD | 0.2% |
|---|---|
| Program size | ~300 bytes |
Any standard ST7 Microcontroller (MCU) can be used.
The solution requires two external resistors per COM line.