mc68hc05l25 Freescale Semiconductor, Inc, mc68hc05l25 Datasheet - Page 100

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

LCD Driver
11.3 Functional Description
The following paragraphs provide a functional description of the LCD driver. See
simplified schematic of the LCD system.
11.3.1 LCD Control Register
LCDE — LCD Enable
PBEH — Port B Enable High Nibble
DUTY — Duty Cycle Select
PBEL — Port B Enable Low Nibble
Bits 3 and 2 — Reserved
FC and LC — Fast Charge and Low Current
100
Setting this bit enables the LCD waveforms to appear on the pins. Reset clears this bit.
This bit enables the port B I/O bits 4–7 that are multiplexed with frontplane drivers 20–17. Reset clears
this bit.
This bit selects the duty cycle of the LCD waveforms between 1/3 duty and 1/4 duty and selects either
BP3 or FP0 for the muxed pin. Reset clears this bit.
This bit enables the port B I/O bits 0–3 that are multiplexed with frontplane drivers 24–21. Reset clears
this bit.
These bits are unused and always read as zero.
These bits are used to select various values of resistors in the voltage generator resistor chain. Reset
clears these bits.
1 = LCD drivers are operational. Each FP and BP driver outputs the driver waveform specified by
0 = LCD drivers are halted. All FP and BP drivers have the same electric potential as V
0 = PB4–PB7/FP20–FP17 pins function as port B bits 4–7.
0 = PB4–PB7/FP20–FP17 pins function as LCD frontplane drivers 20–17.
1 = 1/3 duty cycle is selected and BP3/FP0 pin functions as FP0.
0 = 1/4 duty cycle is selected and BP3/FP0 pin functions as BP3.
1 = PB0–PB3/FP24–FP21 pins function as port B bits 0–3.
0 = PB0–PB3/FP24–FP21 pins function as LCD frontplane drivers 24–21.
the data latch.
are disconnected to reduce DC current.
Address:
Reset:
Read:
Write:
$0020
LCDE
Bit 7
0
= Unimplemented
PBEH
6
0
Figure 11-2. LCD Control Register
MC68HC05L25 Data Sheet, Rev. 3.1
DUTY
5
0
PBEL
4
0
3
0
0
2
0
0
FC
1
0
Figure 11-15
Freescale Semiconductor
Bit 0
LC
0
DD
for a
. R
LCD
s