Preliminary
S3C2451X RISC MICROPROCESSOR
SYSTEM CONTROLLER
2-21
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
INDIVIDUAL REGISTER DESCRIPTIONS
CLOCK SOURCE CONTROL REGISTERS (LOCKCON0, LOCKCON1, OSCSET, MPLLCON, AND EPLLCON)
The six registers control two internal PLLs and an external oscillator. The output frequency of the PLL is
determined by the divider values of MPLLCON and EPLLCON. The stabilization time for PLLs and the oscillator is
controlled by LOCKCON0/1 and OSCSET, respectively.
Register Address
R/W
Description
Reset
Value
LOCKCON0
0x4C00_0000
R/W
MPLL lock time count register
0x0000_FFFF
LOCKCON1
0x4C00_0004
R/W
EPLL lock time count register
0x0000_FFFF
OSCSET 0x4C00_0008
R/W
Oscillator
stabilization control register
0x0000_8000
MPLLCON 0x4C00_0010
R/W
MPLL
configuration register
0x0185_40C0
EPLLCON 0x4C00_0018
R/W
EPLL
configuration register
0x0120_0102
EPLLCON_K 0x4C00_001C R/W
EPLL
configuration register for K value
0x0000_0000
Conventional PLL requires stabilization duration after the PLL is ON. The duration can be varied according to the
device variation. Thus, software must adjust these fields with appropriate values in the LOCKCON0/1 register
whose values mean the number of the external reference clock.
LOCKCON0 Bit
Description Initial
Value
RESERVED [31:16]
RESERVED
0x0000
M_LTIME [15:0]
MPLL lock time count value for ARMCLK, HCLK, and PCLK
Typically, M_LTIME must be longer than 300 usec.
0xFFFF
LOCKCON1 Bit
Description Initial
Value
RESERVED [31:16]
RESERVED
0x0000
E_LTIME [15:0]
EPLL lock time count value for UARTCLK, SPICLK and etc.
Typically, E_LTIME must be longer than 300 usec.
0xFFFF
In general, an oscillator requires stabilization time. This register specifies the duration based on the reference
clock.
OSCSET Bit
Description
Initial
Value
RESERVED [31:0]
RESERVED
0x0000
XTALWAIT [15:0]
Crystal oscillator settle-down wait time, this value is valid
when s3c2451 is wakeup by stop mode
0x8000