146
CHAPTER 12 CLOCK OUTPUT CONTROL CIRCUIT
12.3 Clock Output Control Circuit Control Registers
The following two types of registers are used to control the CKU.
• Clock output selection register (CKS)
• Port mode register 6 (PM6)
(1) Clock output selection register (CKS)
This register sets output clock.
CKS is set with a 1-bit or 8-bit memory manipulation instruction.
RESET input clears CKS to 00H.
Figure 12-2. Clock Output Selection Register (CKS) Format
Address: FF40H After Reset: 00H R/W
Symbol
7
6
5
4
3
2
1
0
CKS
0
0
0
CLOE
0
CCS2
CCS1
CCS0
CLOE
PCL Output Enable/Disable Specification
0
Stop clock division circuit operation.
1
Enable clock division circuit operation.
CCS2
CCS1
CCS0
PCL Output Clock Selection
0
0
0
f
X
(8.38 MHz)
0
0
1
f
X
/2 (4.19 MHz)
0
1
0
f
X
/2
2
(2.09 MHz)
0
1
1
f
X
/2
3
(1.04 MHz)
1
0
0
f
X
/2
4
(524 kHz)
1
0
1
f
X
/2
5
(262 kHz)
1
1
0
f
X
/2
6
(131 kHz)
1
1
1
f
X
/2
7
(65.5 kHz)
Cautions 1. When rewriting CKS to other data, stop the timer operation beforehand.
2. Bit 3 and bits 5 to 7 must be set to 0.
Remarks 1. f
X
= main system clock oscillation frequency
2. Figures in parentheses apply to operation with f
X
= 8.38 MHz.
Summary of Contents for mPD780973 Series
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