Table of Contents
Advertisement
(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
Downloaded from
Elcodis.com
electronic components distributor
CHAPTER 5 CLOCK GENERATOR
Figure 5-6. Format of Main Clock Mode Register (MCM)
Note
After reset: 00H
R/W
7
6
0
0
XSEL
MCM0
Selection of clock supplied to main system clock and peripheral hardware
0
0
Internal high-speed oscillation clock
(f
)
RH
0
1
1
0
Setting prohibited
1
1
High-speed system clock (f
MCS
0
Operates with internal high-speed oscillation clock
1
Operates with high-speed system clock
Note Bit 1 is read-only.
Cautions 1. XSEL can be changed only once after a reset release.
2. Be sure to set XSEL=1, MCM0=1 if using the USB function.
3. A clock other than f
regardless of the setting of XSEL and MCM0.
• Watchdog timer (operates with internal low-speed oscillation clock)
• When "f
", "f
RL
(operates with internal low-speed oscillation clock)
• Peripheral hardware selects the external clock as the clock source
(Except when the external count clock of TM00 is selected (TI000 pin valid
edge))
Preliminary User's Manual U19014EJ1V0UD
5
4
3
0
0
0
Main system clock (f
)
XP
)
XH
Main system clock status
is supplied to the following peripheral functions
PRS
7
9
/2
", or "f
/2
" is selected as the count clock for 8-bit timer H1
RL
RL
<2>
<1>
<0>
XSEL
MCS
MCM0
Peripheral hardware clock (f
PRS
Internal high-speed oscillation clock
(f
)
RH
High-speed system clock (f
)
XH
)
89
Advertisement
Table of Contents
