MC9S12HZ256 Datasheet, PDF (241/692 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 8
Liquid Crystal Display (LCD32F4BV1)
8.1 Introduction
The LCD32F4B driver module has 32 frontplane drivers and 4 backplane drivers so that a maximum of
128 LCD segments are controllable. Each segment is controlled by a corresponding bit in the LCD RAM.
Four multiplex modes (1/1, 1/2, 1/3, 1/4 duty), and three bias (1/1, 1/2, 1/3) methods are available. The V₀
voltage is the lowest level of the output waveform and V₃ becomes the highest level. All frontplane and
backplane pins can be multiplexed with other port functions.
The LCD32F4B driver system consists of five major sub-modules:
• Timing and Control – consists of registers and control logic for frame clock generation, bias
voltage level select, frame duty select, backplane select, and frontplane select/enable to produce
the required frame frequency and voltage waveforms.
• LCD RAM – contains the data to be displayed on the LCD. Data can be read from or written to the
display RAM at any time.
• Frontplane Drivers – consists of 32 frontplane drivers.
• Backplane Drivers – consists of 4 backplane drivers.
• Voltage Generator – Based on voltage applied to VLCD, it generates the voltage levels for the
timing and control logic to produce the frontplane and backplane waveforms.
8.1.1 Features
The LCD32F4B includes these distinctive features:
• Supports five LCD operation modes
• 32 frontplane drivers
• 4 backplane drivers
— Each frontplane has an enable bit respectively
• Programmable frame clock generator
• Programmable bias voltage level selector
• On-chip generation of 4 different output voltage levels
8.1.2 Modes of Operation
The LCD32F4B module supports five operation modes with different numbers of backplanes and different
biasing levels. During pseudo stop mode and wait mode the LCD operation can be suspended under
MC9S12HZ256 Data Sheet, Rev. 2.04
Freescale Semiconductor
241