Technical information

43
MITSUBISHI MICROCOMPUTERS
3820 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
Fig. 38 State transitions of internal clock φ
CM4 : Port Xc switch bit
0: I/O port
1: X
CIN, XCOUT
CM5 : Main clock (XIN–XOUT) stop bit
0: Oscillating
1: Stopped
CM
6: Main clock division ratio selection bit
0: f(X
IN)/2 (high-speed mode)
1: f(X
IN)/8 (middle-speed mode)
CM
7: Internal system clock selection bit
0: X
IN–XOUT selected
(middle-/high-speed mode)
1: X
CIN–XCOUT selected
(low-speed mode)
Notes
Reset
CM4
CM7
CM4
CM5
CM6
CM6
CPU mode register
(CPUM : address 003B
16)
7
4
CM7
CM5
CM6
CM6
"0""1"
"0"
"1"
"0"
"1"
"0"
"1"
"0"
"1"
"0"
"1"
"0"
"1"
"0""1"
"0""1"
"0""1"
CM
4
CM
6
"1"
"0"
"0"
"1"
CM
4
CM
6
"0"
"1"
"0"
"1"
CM
5
CM
6
"1"
"0"
"0"
"1"
CM
5
CM
6
"0"
"1"
"0"
"1"
CM7=0(8MHz selected)
CM
6=1(Middle-speed)
CM
5=0(8MHz oscillating)
CM
4=0(32kHz stopped)
CM
7=0(8MHz selected)
CM
6=0(High-speed)
CM
5=0(8MHz oscillating)
CM
4=0(32kHz stopped)
CM
7=0(8MHz selected)
CM
6=0(High-speed)
CM
5=0(8MHz oscillating)
CM
4=1(32kHz oscillating)
CM
7=1(32kHz selected)
CM
6=0(High-speed)
CM
5=0(8MHz oscillating)
CM
4=1(32kHz oscillating)
CM
7=1(32kHz selected)
CM
6=0(High-speed)
CM
5=1(8MHz stopped)
CM
4=1(32kHz oscillating)
CM
7=0(8MHz selected)
CM
6=1(Middle-speed)
CM
5=0(8MHz oscillating)
CM
4=1(32kHz oscillating)
CM
7=1(32kHz selected)
CM
6=1(Middle-speed)
CM
5=0(8MHz oscillating)
CM
4=1(32kHz oscillating)
CM
7=1(32kHz selected)
CM
6=1(Middle-speed)
CM
5=1(8MHz stopped)
CM
4=1(32kHz oscillating)
Low-speed mode (f(φ) =16 kHz)
Low-speed mode (f(φ) =16 kHz)
Low-speed mode (f(φ) =16 kHz) Low-speed mode (f(φ) =16 kHz)
High-speed mode (f(φ) =4MHz)
Middle-speed mode (f(φ) =1 MHz)
Middle-speed mode (f(φ) =1 MHz)
High-speed mode (f(φ) =4MHz)
t
2.
XIN before the switching from the low-speed mode to middle-/high-
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 returned to the source mode when the stop mode or the wai
mode is released.
3: Timer and LCD operate in the wait mode.
4: In middle-/high-speed mode, when the stop mode is released, a delay of approximately 1 ms occurs automatically by timer 1 and
timer 2.
5: In low-speed mode, when the stop mode is released, a delay of approximately 0.25 s occurs automatically by timer 1 and timer
6: Wait until oscillation stabilizes after oscillating the main clock
speed mode.
7: The example assumes that 8 MHz is being applied to the
XIN pin and 32 kHz to the XCIN pin. φ indicates the internal clock.