MPC555
/
MPC556
RESET
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
7-12
7.5.2 Hard Reset Configuration Word
The hard reset configuration word, which is sampled from the internal data bus on the
negation of HRESET, is shown below. The reset configuration word is not a register in
the memory map. Most of the bits in the configuration are located in registers in the
USIU. The user should refer to the appropriate register definition for a detailed descrip-
tion of each control bit.
Hard Reset Configuration Word
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
EARB
IP
BDRV
BDIS
BPS
Reserved
DBGC
DBPC ATWC
EBDF
Re-
served
DEFAULT:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LSB
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
PRPM
SC
ETRE
FLEN
EN_
COMP
EXC_
COMP
RE-
SERVED
Reserved
ISB
DME
DEFAULT:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 7-5 Hard Reset Configuration Word Bit Descriptions
Bit(s)
Name
Description
0
EARB
External arbitration. Refer to
6.13.1.1 SIU Module Configuration Register
for a detailed bit
definition.
0 = Internal arbitration is performed
1 = External arbitration is assumed
1
IP
Initial interrupt prefix. This bit defines the initial value of the MSR[IP] bit immediately after re-
set. MSR[IP] defines the interrupt table location.
0 = MSR[IP] = 0 after reset
1 = MSR[IP] = 1 after reset
2
BDRV
Bus pins drive strength. This bit determines the driving capability of the bus pins (address,
data, and control) and the CLKOUT pin. For details, refer to description of the COM bits in
8.12.1 System Clock Control Register (SCCR)
. The default value is full drive strength for
the bus pins and CLKOUT.
0 = Full drive
1 = Reduced drive
3
BDIS
External boot disable. If a write to the OR0 register occurs after reset, this bit definition is ig-
nored.
0 = Memory controller bank 0 is active and matches all addresses immediately after reset
1 = Memory controller is not activated after reset.
4:5
BPS
Boot port size. If a write to the OR0 register occurs after reset, this field definition is ignored.
00 = 32-bit port (default)
01 = 8-bit port
10 = 16-bit port
11 = Reserved
6:8
—
Reserved
9:10
DBGC
Debug pins configuration. See
6.13.1.1 SIU Module Configuration Register
for this field
definition. The default value is for these pins to function as VFLS[0:1], BI, BR, BG, and BB.
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
.
..