Fujitsu MB91460 SERIES FR60 User Manual page 268

Chapter 18 Timebase Counter
4.Registers
4.2 CLKR: Clock Source Control Register
Selects the clock source for the base clock used to run the MCU and controls the PLL.
Note: See also the "Chapter 13 Clock Control (Page
• CLKR: Address 0484h (Access: Byte)
7 6
- -
X X
X X
R/W0 R/W0
(See "Meaning of Bit Attribute Symbols (Page
• Bit7-4: Reserved bit Always write "0" to this bit. The read value is the value written.
• Bit3: Subclock selection enable (SCKEN)
• Setting this bit to "1" enables the subclock to be selected.
• Bit2: Main PLL operation enable (PLL1EN)
• Setting this bit to "1" starts main PLL operation. Main PLL can be selected as the operating clock after the
main PLL has locked.
• Bit1-0: Clock source selection
CLKS1 CLKS0
0 0 The main clock input from X0/X1 divided by 2 (initial value)
0 1 The main clock input from X0/X1 divided by 2
1 0 Main PLL
1 1 Subclock
When changing the clock mode, the value of CLKS0 cannot be modified if CLKS1 is "1"
The table below lists the cases when the CLKS1 - CLKS0 bits may or may not be modified.
Table 4-1 Cases When the CLKS1 and CLKS0 Bits May or May Not be Modified
Modify permitted
"00" -> "01" or "10"
"01" -> "11" or "00"
"10" -> "00"
"11" -> "01"
Example: To select the subclock after an INIT reset, first write "01
The clock source for the timebase counter during the oscillation stabilization wait time is set by the clock source
selection bits.
CLKS1 CLKS0
0 0
0 1
1 0
1 1
252
5 4 3
- - SCKEN
X X 0
X X X
R/W0 R/W0 R/W
Clock source setting
Clock source for timebase
counter during oscillation stabilization wait time
The main clock input from X0/X1 divided by 2 (initial value)
Subclock
No.189)".
2 1
PLL1EN CLKS1
0 0
X X
R/W R/W
No.10)" for details of the attributes.)
Modify not permitted
"10" -> "01" or "11"
"11" -> "00" or "10"
" and then write "11
B
0 bit
CLKS0
Initial value
0
(INIT pin input)
Initial value
X
(Software reset)
R/W Attribute
Mode
Main clock mode
Main clock mode
Main clock mode
Subclock mode
"00" -> "11"
"01" -> "10"
" (subclock)
B
Mode
Main clock mode
Subclock mode