38C3 Group User’s Manual
HARDWARE
1-43
Fig. 45 State transitions of system clock
FUNCTIONAL DESCRIPTION
CM4 : Port Xc switch bit
0: I/O port function
1: XCIN-XCOUT oscillating function
CM5 : Main clock (XIN- XOUT) stop bit
0: Oscillating
1: Stopped
CM6: Main clock division ratio selection bit
0: f(XIN)/2(High-speed mode)
1: f(XIN)/8 (Middle-speed mode)
CM7: Internal system clock selection bit
0: XIN–XOUT selected (Middle-/High-speed mode)
1: XCIN–XCOUT selected (Low-speed mode)
Reset
CM
4
CM
7
CM
4
CM
5
CM6
CPU mode register
(CPUM : address 003B 16)
b7
b4
CM
7
CM
5
CM6
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
“0”
“1”
CM
4
“1”
“0”
CM
4
“0”
“1”
“0”
“1”
CM
5
“1”
“0”
“1”
CM
5
“0”
“1”
“0”
“1”
“0”
“1”
CM
6
CM
6
CM
6
CM
6
CM7=0(8 MHz selected)
CM6=1(middle-speed)
CM5=0(8 MHz oscillating)
CM4=0(32 kHz stopped)
1: Switch the mode by the allows shown between the mode blocks. (Do not switch between the mode directly without an allow.)
2: The all modes can be switched to the stop mode or the wait mode and return to the source mode when the stop mode or the wait mode is ended.
3: Timer,LCD operate in the wait mode.
4: When the stop mode is ended, a delay of approximately 1 ms occurs by connecting Timer 1 and Timer 2 in middle-/high-speed mode.
5: When the stop mode is ended, a delay of approximately 0.25 s occurs in low-speed mode.
6: Wait until oscillation stabilizes after oscillating the main clock X IN before the switching from the low-speed mode to middle/high-speed mode.
7: The example assumes that 8 MHz is being applied to the X IN pin and 32 kHz to the X CIN pin.
φ indicates the internal system clock.
Middle-speed mode
(f(
φ)=1 MHz)
Middle-speed mode
((f(
φ)=1 MHz)
CM7=0(8 MHz selected)
CM6=0(high-speed)
CM5=0(8 MHz oscillating)
CM4=0(32 kHz stopped)
High-speed mode
(f(
φ) =4 MHz)
CM7=0(8 MHz selected)
CM6=0(high-speed)
CM5=0(8 MHz oscillating)
CM4=1(32 kHz oscillating)
High-speed mode
(f(
φ) =4 MHz)
CM7=1(32 kHz selected)
CM6=0(high-speed)
CM5=0(8 MHz oscillating)
CM4=1(32 kHz oscillating)
Low-speed mode
(f(
φ) =16 kHz)
CM7=1(32 kHz selected)
CM6=0(high-speed)
CM5=1(8 MHz stopped)
CM4=1(32 kHz oscillating)
CM7=0(8 MHz selected)
CM6=1(middle-speed)
CM5=0(8 MHz oscillating)
CM4=1(32 kHz oscillating)
CM7=1(32 kHz selected)
CM6=1(middle-speed)
CM5=0(8 MHz oscillating)
CM4=1(32 kHz oscillating)
Low-speed mode
((f(
φ)=16 kHz)
CM7=1(32 kHz selected)
CM6=1(middle-speed)
CM5=1(8 MHz stopped)
CM4=1(32 kHz oscillating)
Low-speed mode
(f(
φ) =16 kHz)
Low-speed mode
((f(
φ)=16 kHz)
Notes