NEC 78K0 User Manual page 103

(4) Main OSC control register (MOC)
This register selects the operation mode of the X1 input clock.
This register is used to stop the X1 oscillator operation when the CPU is operating with the Ring-OSC clock.
Therefore, this register is valid only when the CPU is operating with the Ring-OSC clock.
MOC can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input clears this register to 00H.
Address: FFA2H After reset: 00H
Symbol <7>
MOC MSTOP
MSTOP
0
1
Cautions 1. Make sure that bit 1 (MCS) of the main clock mode register (MCM) is 1 before
CHAPTER 5 CLOCK GENERATOR
Figure 5-5. Format of Main OSC Control Register (MOC)
R/W
6 5
0 0
X1 oscillator operating
X1 oscillator stopped
setting MSTOP.
2. To stop X1 oscillation when the CPU is operating on the subsystem clock, set bit
7 (MCC) of the processor clock control register (PCC) to 1 (setting by MSTOP is
not possible).
User's Manual U16227EJ2V0UD
4 3 2
0 0 0
Control of X1 oscillator operation
1 0
0 0
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