MPC555
/
MPC556
SYSTEM CONFIGURATION AND PROTECTION
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
6-24
* The reset value is a reset configuration word value, extracted from the indicated internal data bus line. Refer to
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LSB
31
PRPM SLVM
0
SIZE
SUPU
INST
RESERVED
RESV CONT
0
TRAC SIZEN
RESERVED
RESET:
ID16*
0
0
0
1
0
1
0
0
1
1
0
1
1
0
0
Table 6-12 EMCR Bit Descriptions
Bit(s)
Name
Description
0:15
—
Reserved
16
PRPM
Peripheral mode. In this mode, the internal RCPU core is shut off and an alternative master on
the external bus can access any internal slave module. The reset value of this bit is determined
by the reset configuration word bit 16. The bit can also be written by software.
0 = Normal operation
1 = Peripheral mode operation
17
SLVM
Slave mode (valid only if PRPM = 0). In this mode, an alternative master on the external bus can
access any internal slave module while the internal RCPU core is fully operational. If PRPM is
set, the value of SLVN is a “don’t care.”
0 = Normal operation
1 = Slave mode
18
—
Reserved
19:20
SIZE
Size attribute. If SIZEN = 1, the SIZE bits controls the internal bus attributes as follows:
00 = Double word (8 bytes)
01 = Word (4 bytes)
10 = Half word (2 bytes)
11 = Byte
21
SUPU
Supervisor/user attribute. SUPU controls the supervisor/user attribute as follows:
0 = Supervisor mode access permitted to all registers
1 = User access permitted to registers designated “user access”
22
INST
Instruction attribute. INST controls the internal bus instruction attribute as follows:
0 = Instruction fetch
1 = Operand or non-CPU access
23:24
—
Reserved
25
RESV
Reservation attribute. RESV controls the internal bus reservation attribute as follows:
0 = Storage reservation cycle
1 = Not a reservation
26
CONT
Control attribute. CONT drives the internal bus control bit attribute as follows:
0 = Access to MPC555 / MPC556 control register, or control cycle access
1 = Access to global address map
27
—
Reserved
28
TRAC
Trace attribute. TRAC controls the internal bus program trace attribute as follows:
0 = Program trace
1 = Not program trace
29
SIZEN
External size enable control bit. SIZEN determines how the internal bus size attribute is driven:
0 = Drive size from external bus signals TSIZE[0:1]
1 = Drive size from SIZE0, SIZE1 in EMCR
30:31
—
Reserved
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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