Holtek HT46R22 LCD Display Driving Using General I/O Ports Manual

About this manual

This document explains the principle and wiring for driving an LCD with limited I/O pins using the HT46R22 24‑pin microcontroller. It describes how to configure COM and SEG lines, set pull‑up/pull‑down resistors, and achieve three voltage levels (VDD, ½ VDD, 0 VDD) for LCD segments.

A complete program example is provided, including initialization, timer interrupt handling, segment and COM pulse generation, and a BCD table for displaying numbers 0‑99. The source code is written in assembly and shows how to map PA0‑PA3 and PB3‑PB7 to segment and COM signals. This manual is written in Chinese.

What's inside

• Introduction
• Usage Instructions
• Program Example
• Segment Mapping Table
• Interrupt Service Routine
• Timer Handling
• COM & SEGMENT Output
• BCD Table

Specifications

Frequently asked questions

Which pins are used for SEG0‑SEG5 and COM0‑COM2 on the HT46R22?

PA0‑PA3 and PB3‑PB5 are used for SEG0‑SEG5, while PB3, PB6, and PB7 are used for COM0‑COM2.