
CHAPTER 5 CLOCK GENERATOR
Preliminary User’s Manual U16228EJ1V0UD
128
(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.
Figure 5-6. Format of Main OSC Control Register (MOC)
Address: FFA2H
After reset: 00H
R/W
Symbol
76543210
MOC
MSTOP
000000
0
MSTOP
Control of X1 oscillator operation
0
X1 oscillator operating
1
X1 oscillator stopped
Cautions 1. Make sure that bit 1 (MCS) of the main clock mode register (MCM) is 1 before
setting MSTOP.
2. To stop X1 oscillation during operation with the subsystem clock, set bit 7 (MCC)
of the processor clock control register (PCC) to 1 (setting by MSTOP is not
possible).
(5) Oscillation stabilization time counter status register (OSTC)
This is the status register of the X1 input clock oscillation stabilization time counter. If the Ring-OSC clock is used
as the CPU clock, the X1 input clock oscillation stabilization time can be checked.
OSTC can be read by a 1-bit or 8-bit memory manipulation instruction.
RESET input, the STOP instruction, MSTOP = 1, and MCC = 1 clear OSTC to 00H.
Figure 5-7. Format of Oscillation Stabilization Time Counter Status Register (OSTC)
Address: FFA3H
After reset: 00H
R
Symbol
76543210
OSTC
0
MOST11
MOST13
MOST14
MOST15
MOST16
MOST11
MOST13
MOST14
MOST15
MOST16
Oscillation stabilization time status
10
0
2
11/fXP min. (204.8
s min.)
11
0
2
13/fXP min. (819.2
s min.)
11
1
0
2
14/fXP min. (1.64 ms min.)
11
1
0
2
15/fXP min. (3.27 ms min.)
11
1
2
16/fXP min. (6.55 ms min.)
Caution
After the above time has elapsed, the bits are set to 1 in order from MOST11 and
remain 1.
Remarks 1. Values in parentheses are for operation with fXP = 10 MHz.
2. fXP: X1 input clock oscillation frequency