mc68hc05l25 Freescale Semiconductor, Inc, mc68hc05l25 Datasheet - Page 99

• Manufacturer Part Number: mc68hc05l25
• Description: M68hc05 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 11
LCD Driver
11.1 Introduction
The MC68HC05L25 has 25 or 24 frontplane (FP) and three or four backplane (BP) drivers. The number
of drivers for the FP and BP can be selected by software option. The maximum number of segments
configurable is either 24 x 4 = 96 or 25 x 3 = 75 segments.
The MC68HC05L25 uses a 1/3 biasing method. The bias voltages are supplied from an external source
using the V
There are 11 bytes of data latch for selection (turned on) or nonselection (turned off) of segments. Each
byte consists of two FP drivers and either three or four BP drivers depending on the duty configured. The
data latch is available in memory locations $21 through $2D and can be accessed by the CPU using the
conventional memory access method (LOAD, STORE, BIT operations, etc.).
The clock which forms the LCD FP and BP waveforms is supplied by the time base module.
11.2 Block Diagram
Figure 11-1
Freescale Semiconductor
BP3/FP0
LCD
V
FP4
FP3
FP2
FP1
BP2
BP1
BP0
illustrates the block diagram of the LCD module.
LCD
pin. Voltages V
1/3
1/4
LCD1
LCD FRONTPLANE DRIVER + DATA LATCH
Figure 11-1. LCD Block Diagram
, V
MC68HC05L25 Data Sheet, Rev. 3.1
LCD2
1/3
LCDE (LCDC)
, and V
CONTROL
STATE
1/4
LCD3
are generated internally with resistor divider.
PB7/FP17
PB6/FP18
PB5/FP19
PB4/FP20
PB3/FP21
PB2/FP22
PB1/FP23
PB0/FP24
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