Rev. 1.00
48
September 11, 2018
Rev. 1.00
49
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
• SCC Register
Bit
7
6
5
4
3
2
1
0
Name
CKS2
CKS1
CKS0
—
FHS
FSS
FHIDEN FSIDEN
R/W
R/W
R/W
R/W
—
R/W
R/W
R/W
R/W
POR
0
0
0
—
0
0
0
0
Bit 7~5
CKS2~CKS0
: System clock selection
000: f
H
001: f
H
/2
010: f
H
/4
011: f
H
/8
100: f
H
/16
101: f
H
/32
110: f
H
/64
111: f
SUB
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
or f
SUB
, a divided version
of the high speed system oscillator can also be chosen as the system clock source.
Bit 4
Unimplemented, read as "0"
Bit 3
FHS
: High Frequency clock selection
0: HIRC
1: HXT
Bit 2
FSS
: Low Frequency clock selection
0: LIRC
1: LXT
Bit 1
FHIDEN
: High Frequency oscillator control when CPU is switched off
0: Disable
1: Enable
This bit is used to control whether the high speed oscillator is activated or stopped
when the CPU is switched off by executing an "HALT" instruction.
Bit 0
FSIDEN
: Low Frequency oscillator control when CPU is switched off
0: Disable
1: Enable
This bit is used to control whether the low speed oscillator is activated or stopped
when the CPU is switched off by executing an "HALT" instruction.
• HIRCC Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
—
—
HIRC1
HIRC0
HIRCF
HIRCEN
R/W
—
—
—
—
R/W
R/W
R
R/W
POR
—
—
—
—
0
0
0
1
Bit 7~4
Unimplemented, read as "0"
Bit 3~2
HIRC1~HIRC0
: HIRC frequency selection
00: 4MHz
01: 8MHz
10: 12MHz
11: 4MHz
When the HIRC oscillator is enabled or the HIRC frequency selection is changed
by application program, the clock frequency will automatically be changed after the
HIRCF flag is set to 1. It is recommended that the HIRC frequency selected by these
bits is the same as the frequency determined by the configuration option to ensure a
higer HIRC frequency accuracy spedified in the A.C. chanracteristics.