56
MITSUBISHI MICROCOMPUTERS
M37733MHBXXXFP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
PRELIMINARY
Notice:
This
is not
a final
specification.
Some
parametric
limits
are
subject
to change.
Oscillation circuit control register 0
XCOUT drivability selection bit
0 : LOW
1 : HIGH
Main clock stop bit
0 : Main-clock oscillation is available.
1 : Main-clock oscillation is stopped.
System clock selection bit
Port-XC selection bit = “0” (Sub clock is not used.)
0 : Main clock is selected.
1 : Main clock divided by 8 is selected.
Port-XC selection bit = “1” (Sub clock is used.)
0 : Main clock is selected.
1 : Sub clock is selected.
Port-Xc selection bit
0 : Ports P77 and P76 are selected. (Sub clock is not used.)
1 : Pins XCIN and XCOUT are selected. (Sub clock is used.)
System clock stop bit at wait state
0 : Clocks f2 to f512 are operating at WIT state
1 : Clocks f2 to f512 stop at WIT state
Signal output disable selection bit (Refer to Table 7.)
Address
6C16
Note. Write to the oscillation circuit control
register 1 as the flow shown in Figure 64.
CM6 CM5 CM4 CM3 CM2
CM0
76543
2
1
0
Oscillation circuit control register 1
Main clock division selection bit
0 : Main clock is divided by 2.
1 : Main clock is not divided by 2.
Main clock external input selection bit
0 : Main-clock oscillation circuit is operating by itself.
Watchdog timer is used at returning from STP state.
1 : Main-clock is input externally.
Watchdog timer is not used at returning from STP state.
Sub clock external input selection bit
0 : Sub-clock oscillation circuit is operating by itself.
Port P76 functions as XCOUT pin.
Watchdog timer is used at returning from STP state.
1 : Sub-clock is input externally.
Port P76 functions as I/O port.
Watchdog timer is not used ar returning from STP state.
X : Not used
0 : Always “0” (However, writing data “5516” shown in Figure 64 is possible.)
Clock prescaler reset bit
Address
6F16
CC0
CC1
CC2
0
76543
2
1
0
Fig. 63 Bit configuration of oscillation circuit control registers 0, 1
Fig. 64 How to write data in oscillation circuit control register 1
Writing data “8016” (LDM instruction)
Reset clock prescaler
Writing data “5516” (LDM instruction)
Writing data “0Y16” (LDM instruction)
CC2 to CC0 selection bits
How to reset clock prescaler
How to write in CC2 to CC0 selection bits
Note. “Y” is the sum of bits to be set. For example, when
setting bits 2 and 1 to “1”, “Y” becomes “6”.
Next instruction