
46
Tentative Specifications REV.A
S
pecifications in this manual are tentative and subject to change.
Status Transition of BCLK
Mitsubishi microcomputers
M16C / 62T Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
deveopmen
Status Transition of BCLK
Power dissipation can be reduced and low-voltage operation achieved by changing the count source for
BCLK. Table 1.13.4 shows the operating modes corresponding to the settings of system clock control
registers 0 and 1.
After a reset, operation defaults to division by 8 mode. When shifting to stop mode, the main clock division
select bit 0 (bit 6 at address 0006
16
) is set to “1”. The following shows the operational modes of BCLK.
(1) Division by 2 mode
The main clock is divided by 2 to obtain the BCLK.
(2) Division by 4 mode
The main clock is divided by 4 to obtain the BCLK.
(3) Division by 8 mode
The main clock is divided by 8 to obtain the BCLK. Note that oscillation of the main clock must have
stabilized before transferring from this mode to another mode.
(4) Division by 16 mode
The main clock is divided by 16 to obtain the BCLK.
(5) No-division mode
The main clock is used as the BCLK.
(6) Low-speed mode
f
C
is used as the BCLK. Note that oscillation of both the main and sub clocks must have stabilized before
transferring from this mode to another or vice versa. At least 2 to 3 seconds are required after the sub
clock starts. Therefore, the program must be written to wait until this clock has stabilized immediately
after powering up and after stop mode is cancelled.
(7) Low power dissipation mode
f
C
is the BCLK and the main clock is stopped.
0
1
1
0
0
0
0
0
0
1
1
0
0
1
0
0
0
0
0
0
0
0
1
Invalid
Invalid
Invalid
Invalid
Invalid
1
1
Division by 2 mode
Division by 4 mode
Division by 8 mode
Division by 16 mode
No-division mode
Low-speed mode
Low power dissipation mode
Invalid
1
0
Invalid
Invalid
Invalid
1
0
Invalid
Invalid
Invalid
Invalid
CM17
CM16
CM07
CM06
CM05
CM04
Operating mode of BCLK
Table 1.13.4. Operating modes dictated by settings of system clock control registers 0 and 1