upd78f0730 Renesas Electronics Corporation., upd78f0730 Datasheet - Page 89

• Manufacturer Part Number: upd78f0730
• Description: 8-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

(5) Main clock mode register (MCM)
This register selects the main system clock supplied to CPU clock and clock supplied to peripheral hardware
clock.
MCM can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets this register to 00H.
Address: FFA1H
Symbol
MCM
Note Bit 1 is read-only.
Cautions 1. XSEL can be changed only once after a reset release.
XSEL
MCS
7
0
0
0
1
1
0
1
After reset: 00H
2. Be sure to set XSEL=1, MCM0=1 if using the USB function.
3. A clock other than f
Figure 5-6. Format of Main Clock Mode Register (MCM)
Operates with internal high-speed oscillation clock
Operates with high-speed system clock
regardless of the setting of XSEL and MCM0.
• Watchdog timer (operates with internal low-speed oscillation clock)
• When “f
• Peripheral hardware selects the external clock as the clock source
MCM0
(operates with internal low-speed oscillation clock)
(Except when the external count clock of TM00 is selected (TI000 pin valid
edge))
6
0
0
1
0
1
R/W
Preliminary User’s Manual U19014EJ1V0UD
CHAPTER 5 CLOCK GENERATOR
Internal high-speed oscillation clock
(f
Setting prohibited
High-speed system clock (f
RL
RH
”, “f
Selection of clock supplied to main system clock and peripheral hardware
)
Note
5
0
RL
Main system clock (f
/2
7
”, or “f
PRS
4
0
Main system clock status
RL
is supplied to the following peripheral functions
/2
9
” is selected as the count clock for 8-bit timer H1
XH
XP
)
)
3
0
Internal high-speed oscillation clock
(f
High-speed system clock (f
RH
XSEL
Peripheral hardware clock (f
)
<2>
MCS
<1>
XH
)
MCM0
<0>
PRS
)
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