MPC555
/
MPC556
DEVELOPMENT SUPPORT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
21-12
than) including least significant bits masking according to the size of the bus cycle
for the byte and half-word working modes. Refer to
• Two L-data comparators (each supports equal, not equal, greater than, less than)
including byte, half-word and word operating modes and four byte mask bits for
each comparator. Can be used for fix point data. Match is detected only on the
valid part of the data bus (according to the cycle’s size and the two address least
significant bits).
• No internal breakpoint/watchpoint matching support for unaligned words and half-
words
• The L-data comparators can be programmed to treat fix point numbers as signed
values or as unsigned values
• Combine comparator pairs to detect in and out of range conditions (including ei-
ther signed or unsigned values on the L-data)
• A programmable AND-OR logic structure between the four instruction compara-
tors results with five outputs, four instruction watchpoints and one instruction
breakpoint
• A programmable AND-OR logic structure between the four instruction watch-
points and the four load/store comparators results with three outputs, two load/
store watchpoints and one load/store breakpoint
• Five watchpoint pins, three for the instruction and two for the load/store
• Two dedicated 16-bit down counters. Each can be programmed to count either
an instruction watchpoint or an load/store watchpoint. Only
architecturally
execut-
ed
events are counted, (count up is performed in case of recovery).
• On the fly trap enable programming of the different internal breakpoints using the
serial interface of the development port (refer to
). Soft-
ware control is also available.
• Watchpoints do not change the timing of the machine
• Internal breakpoints and watchpoints are detected on the instruction during in-
struction fetch
• Internal breakpoints and watchpoints are detected on the load/store during load/
store bus cycles
• Both instruction and load/store breakpoints and watchpoints are handled and re-
ported on retirement. Breakpoints and watchpoints on recovered instructions (as
a result of exceptions, interrupts or miss prediction) are not reported and do not
change the timing of the machine.
• Instructions with instruction breakpoints are not executed. The machine branches
to the breakpoint exception routine BEFORE it executes the instruction.
• Instructions with load/store breakpoints are executed. The machine branches to
the breakpoint exception routine AFTER it executes the instruction. The address
of the access is placed in the BAR (breakpoint address register).
• Load/store multiple and string instructions with load/store breakpoints first finish
execution (all of it) and then the machine branches to the breakpoint exception
routine.
• Load/store data compare is done on the load/store, AFTER swap in store access-
es and BEFORE swap in load accesses (as the data appears on the bus).
• Internal breakpoints may operate either in
masked
mode or in
non-masked
mode.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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