pc87591l National Semiconductor Corporation, pc87591l Datasheet - Page 311

• Manufacturer Part Number: pc87591l
• Description: Lpc Mobile Embedded Controllers
• Manufacturer: National Semiconductor Corporation

Revision 1.07
Host Controller Interface Modules
Random Number Generator Control/Status Register, RNGCS (PC87591S)
This register controls the Random Number Generator (RNG) unit. It also provides status of its operation and the validity of
the numbers at its output. The register is cleared on reset.
Location: 00 F930
Type: Varies per bit
Bit
Name
Reset
4-2
7-5
Bit
0
1
Type
R/W
R/W
RO
16
RNGE (Random Number Generator Enable). Enables the operation of the RNG. This bit should be
cleared to reduce power consumption when the RNG is not required. Some wake-up time may apply
before the first number is generated after RNG activation.
0: RNG disabled (default)
1: RNG enabled
DVALID (Data Valid). Indicates that valid data may be read from RNGD register.
0: Data not valid; RNGD always reads 00
1: Data valid; a random number is read
CLKP (Clock Pre-Scaler). Defines the pre-scale ratio between the RNG internal clocks and the core
clock. To change the CLP contents: (a) Clear RNGE; (b) Change CLKP (c); Set RNGE to re-enable the
RNG. CLKP may be set to a value above the actual clock frequency of the core, but it should not be
set to a lower value than the CLK frequency.
Bits
4 3 2
0 0 0:
0 0 1:
0 1 0:
0 1 1:
1 0 0:
1 0 1:
1 1 0:
1 1 1:
Reserved.
7
0
Reserved
Description
15-20 MHz (default)
12-15 MHz
9-12 MHz
7-9 MHz
6-7 MHz
5-6 MHz
4-5 MHz
3-4 MHz
6
0
5
0
(Continued)
311
4
0
16
(default)
Description
CLKP
3
0
0
2
DVALID
1
0
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RNGE
0
0