Rev. 1.00
34
��ne ��� �01�
Rev. 1.00
35
��ne ��� �01�
HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
NORMAL Mode
As the name suggests this is one of the main operating modes where the microcontroller has all of
its functions operational and where the system clock is provided by the high speed oscillator. This
mode operates allowing the microcontroller to operate normally with a clock source coming from
the HIRC oscillator. The high speed oscillator will however first be divided by a ratio ranging from 1
to 64, the actual ratio being selected by the HLCLK bit and CKS2~CKS0 bits in the SMOD register.
Although a high speed oscillator is used, running the microcontroller at a divided clock ratio reduces
the operating current.
SLEEP Mode
The SLEEP Mode is entered when an HALT instruction is executed and when the IDLEN bit in the
SMOD register is low. In the SLEEP mode the CPU will be stopped. However the f
SUB
and f
S
clocks
will continue to operate.
IDLE0 Mode
The IDLE0 Mode is entered when a
n
HALT instruction is executed and when the IDLEN bit in the
SMOD
register is high and the FSYSON bit in the CTRL register is low. In the IDLE0 Mode the
system oscillator will be inhibited from driving the CPU but some peripheral functions will remain
operational such as the Watchdog Timer, TMs and Time Base. In the IDLE0 Mode, the system
oscillator will be stopped, the f
SUB
, f
S
and f
TBC
clocks will be on.
IDLE1 Mode
The IDLE1 Mode is entered when an HALT instruction is executed and when the IDLEN bit in the
SMOD
register is high and the FSYSON bit in the CTRL register is high. In the IDLE1 Mode the
system oscillator will be inhibited from driving the CPU but may continue to provide a clock source
to keep some peripheral functions operational such as TMs and Time Base. In the IDLE1 Mode, the
system oscillator will continue to run, and the f
SUB
, f
S
and f
TBC
clocks will be on.
Control Registers
The SMOD register and the FSYSON bit in the CTRL register are used to control the internal clock
s
within the device.
SMOD Register
Bit
7
6
5
4
3
2
1
0
Name
CKS�
CKS1
CKS0
—
LTO
HTO
IDLEN
HLCLK
R/W
R/W
R/W
R/W
—
R
R
R/W
R/W
POR
0
0
0
—
0
0
1
1
Bit 7~5
CKS2~CKS0
: System clock selection when HLCLK is "0"
000: Reserved
001: Reserved
010: f
H
/64
011: f
H
/32
100: f
H
/16
101: f
H
/
8
110: f
H
/4
111: f
H
/2
These three bits are used to select which clock is used as the system clock source. In
addition to the system clock source directly derived from f
H
, a divided version of the
high speed system oscillator can also be chosen as the system clock source.
Bit 4
Unimplemented, read as "0"