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Application NoteNxp

AN1763: Driving LCD Displays Using the MC68HC705L16 Microcontroller

Application note detailing LCD control and drive functions using the MC68HC705L16 MCU, covering static and multiplexed drive modes, waveforms, and hardware configurations.

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Overview

This application note provides a comprehensive guide to using the NXP MC68HC705L16 microcontroller as a dedicated LCD controller/driver. It explains the fundamentals of LCD operation, including polarization and the requirement for AC waveforms to avoid DC-induced damage. The document details various drive modes including static (1/1 duty), duplex (1/2 duty), triplex (1/3 duty), and quadruplex (1/4 duty), while explaining the relationships between backplane and frontplane waveforms. It includes mathematical formulas for calculating RMS voltages for ON and OFF segments to optimize contrast. Hardware implementation is supported by diagrams for external resistor networks for 1/1, 1/2, and 1/3 bias configurations. The note also references source code for controlling multiplexed displays.

Use Cases

  • Designing embedded systems with integrated segment or dot-matrix LCDs.
  • Implementing LCD driver circuits using the MC68HC705L16 MCU.
  • Calculating voltage bias and duty cycles for custom LCD interfaces.
  • Developing software to control multiplexed liquid crystal displays.

Topics

MC68HC705L16
LCD Controller
Multiplexing
Backplane
Frontplane
RMS Voltage
Static Drive
1/4 Duty
Bias Voltage
Liquid Crystal Display
Contrast Control

Referenced Parts

MC68HC705L16

NXP

Driving LCD Displays Using the MC68HC705L16 Microcontroller

4228

Planar-Standish

text message is displayed on an 8-digit, 15-segment display (Planar-Standish Model 4228)

68HC708LN56

NXP

Automatic Contrast Control of LCD Displays Using the 68HC708LN56 Microcontroller

MC68HC708L16

NXP

Title MC68HC708L16 LCD APPLICATION

AN1763: Driving LCD Displays Using the MC68HC705L16 Microcontroller | Design Resources