deveopmen
Wait Mode
Rev.B2 for proof reading
Mitsubishi Microcomputers
M32C/83 group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
74
CPU clock (BCLK)
Main clock, sub clock or clock from ring oscillator can be selected as clock source for BCLK.
System clock select bit of system clock control register (bit 7 at address 0006
16
)
0: Main clock is selected (X
IN
-X
OUT
)
1: Sub clock is selected (X
CIN
-X
COUT
)
Main clock select bit of oscillation stop detect register (bit 1 at address 000D
16
)
0: Main clock is selected (X
IN
-X
OUT
)
1: Clock from ring oscillator is selected
Table 1.8.3. BCLK source and setting bit
BCLK source
System clock select bit
Main clock select bit
(Bit 7 of address 0006
16
)
(Bit 1 of address 000D
16
)
Main clock (X
IN
-X
OUT
)
0
0
Sub clock (X
CIN
-X
COUT
)
1
0
Ring oscillator
0
1
When main clock or ring oscillator clock is selected as clock source for BCLK, the BCLK is the clock
derived by dividing the main clock or ring oscillator clock by 1, 2, 3, 4, 6, 8, 10, 12, 14 or 16.
Main clock divide rate select bit of main clock division register (bit 0 to 4 at address 000C
16
)
The BCLK is derived by dividing the main clock (X
IN
-X
OUT
) by 8 after a reset. (Main clock division register
= "XXX01000
2
")
When main clock is stopped under changing to stop mode or selecting X
IN
-X
OUT
(main clock select bit =
"0"), the main clock division register is set to the division by 8 ("XXX01000
2
").
When ring oscillator clock is selected as clock source for BCLK, although main clock is stoped, the
contents of main clock division register is maintained.
Peripheral function clock
Main clock, sub clock, PLL clock or ring oscillator clock can be selected as clock source for peripheral
function.
(1) f
1
, f
8
, f
2n
The clock is derived from the main clock or by dividing it by 1, 8 or 2n (n=1 to 15). It is used for the
timer A and timer B counts and serial I/O and UART operation clock.
The f
2n
division rate is set by the count source prescaler register. Figure 1.8.5 shows the count source
prescaler register.
(2) f
AD
This clock has the same frequency as the main clock or ring oscillator clock and is used for A-D
conversion.
(3) f
C32
This clock is derived by dividing the sub clock by 32. It is used for the timer A and timer B counts.
(4) f
PLL
This clock is 80 MHz generated by PLL synthesizer. It is used for the intelligent I/O group 3.