Random Number Generator (RNG)
Freescale Semiconductor
6-3
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
6.2.2
RNG Status Register (RNGSR)
, is a read only register which reflects the internal status of the RNG.
.
1
HA
High assurance. Notifies core when RNGOUT underflow has occurred (RNGOUT is read while empty). Enables the
security violation bit in the RNGSR. Bit is sticky and only cleared by hardware reset.
0 Disable security violation notification.
1 Enable security violation notification.
0
GO
Go bit. Starts/stops random data from being generated. Bit is sticky and only cleared by hardware reset.
0 RNGOUT not loaded with random data.
1 RNGOUT loaded with random data.
IPSBAR
Offset:
0x1F_0004 (RNGSR)
Access: User read-only
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R 0
0
0
0
0
0
0
0
OFS
OFL
0
0
0 SLP EI
FUF LRS SV
W
Reset 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Figure 6-2. RNG Status Register (RNGSR)
Table 6-3. RNGSR Field Descriptions
Field
Description
31–24
Reserved, must be cleared.
23–16
OFS
Output FIFO size. Indicates size of the output FIFO (1 word) and maximum possible value of RNGR[OFL].
15–8
OFL
Output FIFO level. Indicates current number of random words in the output FIFO. Determines if valid random data
is available for reading from the FIFO without causing an underflow condition. On this device, the maximum value for
this field is 0x01.
7–5
Reserved, must be cleared.
4
SLP
Sleep. This bit reflects whether the RNG is in sleep mode. When this bit is set, the RNGA is in sleep mode and the
oscillator clocks are inactive. While in this mode, RNGOUT is not loaded.
0 RNGA is not in sleep mode.
1 RNGA is in sleep mode.
3
EI
Error interrupt. Signals a FIFO underflow. Reset by a write to RNGCR[CI] and not masked by RNGCR[IM].
0 RNGOUT not read while empty.
1 RNGOUT read while empty.
2
FUF
FIFO underflow. Signals FIFO underflow. Reset by reading RNGSR.
0 RNGOUT not read while empty since last read of RNGSR.
1 RNGOUT read while empty since last read of RNGSR.
Table 6-2. RNGCR Field Descriptions (continued)
Field
Description
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60
