MPC555
/
MPC556
BURST BUFFER
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
4-24
4.6.4 BBC Module Configuration Register (BBCMCR)
BBCMCR
— BBC Module Configuration Register
SPR 560
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
RESERVED
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LSB
31
RESERVED
BE
ETRE
OERC
EN_
COMP
2
2. Available only on the MPC556.
EXC_
COMP
DECOMP
_SC_EN
RESERVED
RE-
SET:
0
0
0
ID[19]
1
NOTES:
1. Reset value is taken from the indicated bit of the reset configuration word.
0
0
0
0
0
0
0
0
0
0
0
0
Table 4-8 BBCMCR Bit Descriptions
Bit(s)
Name
Description
16:17
—
Reserved
18
BE
Burst enable
0 = BBC does not request burst accesses
1 = BBC requests burst accesses
19
ETRE
Exception table relocation enable
0 = Exception table relocation is off — the BBC does
not
map exception addresses
1 = Exception table relocation is on — the BBC maps exception addresses to a branch instruction
4.5 Exception Table Relocation
20
OERC
Other exceptions relocation control.
0 = All exceptions except reset are mapped to the internal memory base address.
1 = All exceptions except reset are mapped to the internal memory base a 32 Kbytes.
21
EN_COMP
Enable COMPression – This bit enables the operation of the MPC556 in "Compression ON"
mode. The default state is disabled. This bit is read only.
0 = "Decompression ON" mode is disabled. The MPC556 operates only in "Decompression OFF"
mode.
1 = "Decompression ON" mode is enabled. The MPC556 may operates with both "Decompres-
sion ON" and "Decompression OFF" modes.
The bit value is determined by reset configuration word, bit #21.
22
EXC_
COMP
Exception Compression – This bit determines the operation of the MPC556 with exceptions. If
this bit is set, the MPC556 assumes that the all exception routines code is compressed; other-
wise it is assumed that all exception routines code is not compressed. The reset value is deter-
mined by reset configuration word bit #22.
0 = The MPC556 assumes that exception routines are non-compressed
1 = The MPC556 assumes that ALL exception routines are compressed.
This bit effects only when EN_COMP bit is set.
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
.
..