MPC555
/
MPC556
RESET
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
7-13
7.5.3 Soft Reset Configuration
When a soft reset event occurs, the MPC555 / MPC556 reconfigures the development
port. Refer to
SECTION 21 DEVELOPMENT SUPPORT
for details.
11
DBPC
Debug port 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 development support pins.
12
ATWC
Address type write-enable configuration. Refer to
6.13.1.1 SIU Module Configuration Reg-
for this field definition. The default value is for these pins to function as write-enable pins.
13:14
EBDF
External bus division factor. This field defines the initial value of the external bus frequency.
Refer to
8.12.1 System Clock Control Register (SCCR)
for details. The default value is that
CLKOUT frequency is equal to that of the internal clock (divide by one).
15
—
Reserved
16
PRPM
Peripheral mode enable. This bit determines whether the chip is in peripheral mode. Refer to
6.13.1.3 External Master Control Register (EMCR)
for details. The default value is that pe-
ripheral mode is not enabled.
17:18
SC
Single chip select. Refer to
6.13.1.1 SIU Module Configuration Register
for details.
00 = Extended chip, 32 bits data
01 = Extended chip, 16 bits data
10 = Single chip and show cycles (address)
11 = Single chip
19
ETRE
Exception table relocation enable. This field defines whether the exception table relocation
feature in the BBC is enabled or disabled. The default state is disabled. Refer to
for details.
20
FLEN
Flash Enable — This field determines whether the on-chip flash memory is enabled or dis-
abled out of reset. The default state is disabled, which means that by default, the boot is from
external memory.
0 = Flash disabled — boot is from external memory
1 = Flash enabled
21
EN_
COMP
1
Enable Compression — This bit enables the operation of the MPC555 / MPC556 with com-
pressed code. The default state is disabled. See
22
EXC_
COMP
Exception Compression — This bit determines the operation of the MPC555 with exceptions.
If this bit is set, than the MPC555 assumes that ALL the exception routines are in compressed
code. The default indicates the exceptions are all non-compressed. See
23
—
This bit should not be high in the reset configuration word.
24:27
—
Reserved
28:30
ISB
Initial internal space base select. This field defines the initial value of the ISB field in the IMMR
register. Refer to
6.13.1.2 Internal Memory Map Register
for details. The default state is that
the internal memory map is mapped to start at address 0x0000 0000.
31
DME
Dual mapping enable. This bit determines whether dual mapping of the flash EEPROM mod-
ule is enabled. Refer to
10.8.5 Dual Mapping Base Register (DMBR)
for details.The default
value is for dual mapping to be disabled.
0 = Dual mapping disabled
1 = Dual mapping enabled
NOTES:
1. This bit is available only on the MPC555 / MPC556.
Table 7-5 Hard Reset Configuration Word Bit Descriptions (Continued)
Bit(s)
Name
Description
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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