MPC555
/
MPC556
CENTRAL PROCESSING UNIT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
3-45
3.15.4.2 Machine Check Interrupt
A machine check interrupt indication is received from the U-bus as a possible re-
sponse either to the address or data phase. It is usually caused by one of the following
conditions:
• The accessed address does not exist
• A data error is detected
As defined in the
OEA
, machine check interrupts are enabled when MSR
ME
= 1. If
MSR
ME
= 0 and a machine check interrupt indication is received, the processor enters
the checkstop state. The behavior of the MPC555 / MPC556 in checkstop state is de-
pendent on the working mode as defined in
21.4.1.1 Debug Mode Enable vs. Debug
. When the processor is in debug mode enable, it enters the debug
mode instead of the checkstop state. When in debug mode disable, instruction pro-
cessing is suspended and cannot be restarted without resetting the core.
An indication is sent to the SIU which may generate an automatic reset in this condi-
tion. Refer to
for more details. If the machine check interrupt is
enabled, MSR
ME
= 1, it is taken. If SRR1 Bit 30 = 1, the interrupt is recoverable and the
following registers are set.
For load/store bus cases, these registers are also set:
Execution resumes at offset 0x00200 from the base address indicated by MSR
IP
.
3.15.4.3 Data Storage Interrupt
A data storage interrupt is never generated by the hardware. The software may branch
to this location as a result of implementation-specific data storage protection error in-
terrupt.
Register Name
Bits
Description
Save/Restore Register 0 (SRR0)
Set to the effective address of the instruction that caused the
interrupt
Save/Restore Register 1 (SRR1)
1
Set to 1 for instruction fetch-related errors and 0 for load/
store-related errors
2:4
Set to 0
10:15
Set to 0
Other
Loaded from bits 16:31 of MSR. In the current implementa-
tion, Bit 30 of the SRR1 is never cleared, except by loading a
zero value from MSR
RI
Machine State Register (MSR)
IP
No change
ME
No change
LE
Bit is copied from ILE
Other
Set to 0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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