Registers Controlling Clock Generators - NEC 78K0S/KA1+ Preliminary User's Manual

www.DataSheet4U.com
5.3

Registers Controlling Clock Generators

The clock generators are controlled by the following five registers.
• Processor clock control register (PCC)
• Preprocessor clock control register (PPCC)
• Low-speed Ring-OSC mode register (LSRCM)
• High-speed Ring-OSC mode register (HSRCM)
• Oscillation stabilization time select register (OSTS)
(1) Processor clock control register (PCC) and pre-processor clock control register (PPCC)
These registers are used to specify the division ratio of the system clock.
www.DataSheet4U.com
PCC and PPCC are set by using a 1-bit or 8-bit memory manipulation instruction.
Reset input sets PCC and PPCC to 02H.
Address: FFFBH, After reset: 02H, R/W
Symbol
PCC
Address: FFF3H, After reset: 02H, R/W
Symbol
PPCC
CHAPTER 5 CLOCK GENERATORS
Figure 5-2. Format of Processor Clock Control Register (PCC)
7 6
0 0
Figure 5-3. Format of Preprocessor Clock Control Register (PPCC)
7 6
0 0
PPCC1 PPCC0 PCC1
0 0
0 1
0 0
1 0
0 1
1 0
Other than above
Notes 1. If PPCC = 01H, the clock (f
2. If PPCC = 02H, the clock (f
Preliminary User's Manual U16898EJ1V0UD
5 4 3
0 0 0
5 4 3
0 0 0
Selection of CPU clock (f
0 f
X
Note 1
0 f /2
X
2
1 f /2
X
2 Note 2
0 f /2
X
3 Note 1
1 f /2
X
4 Note 2
1 f /2
X
Setting prohibited
) supplied to the peripheral hardware is f
XP
) supplied to the peripheral hardware is f
XP
2 1 0
0 PCC1 0
2 1 0
0 PPCC1 PPCC0
)
CPU
/2.
X
2
/2 .
X
65