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8-2
MPC180E Security Processor User’s Manual
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Random Number Generator Registers
repeating this process until the required number of 32-bit random words have been
generated. Reads by the EBI can be repeated as soon as the ORDY bit is driven high again.
The process is outlined as follows:
•
CPU sets up MPC180E EBI to generate required number of random words.
•
EBI waits for ORDY signal to be driven low.
•
EBI reads autorand (Automatic Random Output Register), writes to Output FIFO.
•
Repeat previous steps until Output Buffer Count Register reaches zero.
At this point, the EBI can generate an interrupt to inform the CPU that the required number
of random words is waiting in the Output FIFO. These random words can be read by the
CPU for immediate write back to the MPC180E, or written into memory for later use.
8.4 Random Number Generator Registers
Table 8-1 shows RNG registers.
Table 8-1. Random Number Generator Registers
8.4.1 Status Register
Figure 8-1 shows the RNG status register.
Table 8-2 describes the RNG status register fields.
MPC180E 12-Bit Address
Processor 32-Bit Address
Register
Type
0x600
0x0000_1800
Status
R
0x602
0x0000_1808
Autorand output
R
0
17
18
19
30
31
Field
—
ORDY
—
ON/OFF
Reset
0000_0000_0000_0001
R/W
R
Addr
0X600
Figure 8-1. RNG Status Register
Table 8-2. RNG Status Register Field Descriptions
Bits
Name
Description
0–17
—
Reserved.
18
ORDY
The ORDY bit will be driven high when random data is ready. If the user performs a read
of the Random Output Register while the ORDY bit is low, the RNG will assert wait states
until the ORDY bit goes high.
19–30
–
Reserved.
31
ON/OFF A value of 1 indicates that the RNG is on and the shift registers are randomizing.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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F
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sc
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S
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m
ic
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to
r,
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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..