155
Clock Generator
Chapter 4
Preliminary User’s Manual U17566EE1V2UM00
(4)
FCC - FOUTCLK control register
The 8-bit FCC register configures the output clock FOUTCLK that can be used
for external devices.
Access
This register can be read/written in 8-bit or 1-bit units.
Writing to this register is protected by a special sequence of instructions.
Please refer to
“PHCMD - Command protection register” on page 140
for
details.
Address
FFFF F834
H
.
Initial Value
00
H
. The register is initialized by any reset.
Note
1.
FOUTCLK is not influenced by stand-by modes of the microcontroller. It
runs as long as it is enabled and the selected clock source operates.
Application software must stop FOUTCLK by clearing the FOEN bit to
minimize power consumption in stand-by modes.
2.
There is an upper frequency limit for the output buffer of the FOUTCLK
function. Do not select a frequency higher than the maximum output buffer
frequency. Please refer to the Electrical Target Specification for the
frequency limit.
7
6
5
4
3
2
1
0
FOEN
0
a
a)
These bits must not be altered.
0
a
0
a
0
FOSOS
FOCKS1
FOCKS0
R/W
R/W
R/W
R/W
R
R/W
R/W
R/W
Table 4-16
FCC register contents
Bit position
Bit name
Function
7
FOEN
Output clock FOUTCLK enable:
0: FOUTCLK is disabled.
1: FOUTCLK is enabled.
2 to 0
FOSOS,
FOCKS[1:0]
Clock source selection for FOUTCLK:
FOSOS
FOCKS1
FOCKS0
Clock source
X
0
0
Main oscillator
X
0
1
SSCG
X
1
0
PLL
0
1
1
Ring oscillator
1
1
1
Sub oscillator
Caution:
Do not specify the sub oscillator, if the sub oscillator is not enabled or not
connected.
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