HT56R66 Holtek Semiconductor Inc., HT56R66 Datasheet - Page 80

• Manufacturer Part Number: HT56R66
• Description: Tinypower Tm A/d Type With Lcd 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

System Operating Modes
The devices have the ability to operate in several differ-
ent modes. This range of operating modes, known as
Normal Mode, Slow Mode, Idle Mode and Sleep Mode,
allow the devices to run using a wide range of different
slow and fast clock sources. The devices also possess
the ability to dynamically switch between different clocks
and operating modes. With this choice of operating
functions users are provided with the flexibility to ensure
they obtain optimal performance from the device ac-
cording to their application specific requirements.
Clock Sources
In discussing the system clocks for the devices, they
can be seen as having a dual clock mode. These dual
clocks are what are known as a High Oscillator and the
other as a Low Oscillator. The High and Low Oscillator
are the system clock sources and can be selected dy-
namically using the HLCLK bit in the CLKMOD register.
The High Oscillator has the internal name f
source is selected using a configuration option from a
choice of either an external crystal/resonator, external
RC oscillator or external clock source.
The Low Oscillator clock source, has the internal name
f
tion from a choice of either an external 32768Hz oscilla-
tor or the internal 32K_INT oscillator. This internal f
clock, is further modified by the SLOWC0~SLOWC2
bits in the CLKMOD register to provide the low fre-
quency clock source f
Rev. 1.10
SL
, whose source is also selected by configuration op-
SLOW
.
Clock Control Register - CLKMOD
M
whose
SL
, f
M
80
An additional sub internal clock, with the internal name
f
either the internal 32K_INT oscillator or an external
32768 Hz crystal, selected by configuration option. To-
gether with f
internal functions such as the LCD driver, Watchdog
Timer, Buzzer, RTC Interrupt and Time Base Interrupt.
The LCD clock source is the f
8, giving a frequency of 4kHz. The internal clock f
simply a choice of either f
tion option.
Operating Modes
After the correct clock source configuration selections
are made, overall operation of the chosen clock is
achieved using the CLKMOD register. A combination of
the HLCLK and IDLEN bits in the CLKMOD register and
use of the HALT instruction determine in which mode the
device will be run. The devices can operate in the follow-
ing Modes.
SUB
Normal Mode
f
pending upon the LCDEN bit, f
upon the WDT configuration option and WDT control
register.
Slow Mode0
f
lator, f
upon the LCDEN bit, f
WDT configuration option and WDT control register.
M
M
, is a 32kHz clock source which can be sourced from
on, f
off, f
SYS
SLOW
SLOW
=f
SYS
=32K_INT oscillator or the 32768Hz oscil-
SLOW
on, f
/4, it is used as a clock source for certain
, CPU on, f
SYS
=f
HT56R66/HT56R666
M
, CPU on, f
WDT
SUB
or f
S
on/off depending upon the
SUB
on, f
SYS
clock source divided by
WDT
/4, using a configura-
LCD
S
September 8, 2009
on, f
on/off depending
on/off depending
LCD
on/off de-
S
, is