S3C80A5B
CONTROL REGISTERS
4-7
CLKCON
—
System Clock Control Register
D4H
Set 1
Bit Identifier
.7
.6
.5
.4
.3
.2
.1
.0
RESET Value
0
0
0
0
0
0
0
0
Read/Write
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Addressing Mode
Register addressing mode only
.7–.6
Oscillator IRQ Wake-up Function Enable Bit
Not used for S3C80A5B.
.6–.5
Main Oscillator Stop Control Bits
Not used for S3C80A5B.
.4–.3
CPU Clock (System Clock) Selection Bits
(1)
0
0
f
OSC
/16
0
1
f
OSC
/8
1
0
f
OSC
/2
1
1
f
OSC
(non-divided)
.2–.0
Subsystem Clock Selection Bit
(2)
1
0
1
Invalid setting for S3C80A5B.
Other value
Select main system clock (MCLK)
NOTES
:
1. After a reset, the slowest clock (divided by 16) is selected as the system clock. To select faster clock speeds, load the
appropriate values to CLKCON.3 and CLKCON.4.
2. These selection bits are required only for systems that have a main clock and a subsystem clock. The
S3C80A5B uses only the main oscillator clock circuit. For this reason, the setting '101B' is invalid.