NEC mPD789426 Series, User Manual

Page: 107 / 321

CHAPTER 5 CLOCK GENERATOR
User’s Manual U15075EJ1V0UM00
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(3) Subclock control register (CSS)
CSS specifies whether the main system or subsystem clock oscillator is to be selected. It also specifies the
CPU clock operation status.
CSS is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets CSS to 00H.
Figure 5-4. Format of Subclock Control Register
CPU clock operation status
0 0 CLS CSS0 0 0 0 0 CSS
Address After reset R/W
FFF2H 00H R/W
7 6 5 4 3 2 1 0
CLS
0
1
Operation based on the output of the (divided) main system clock
Operation based on the subsystem clock
Selection of the main system or subsystem clock oscillator CSS0
0
1
(Divided) output from the main system clock oscillator
Output from the subsystem clock oscillator
Symbol
Note
Note Bit 5 is read only.
Caution Bits 0 to 3, 6, and 7 must be set to 0.