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MC1321x Reference Manual, Rev. 1.1
Freescale Semiconductor
21-13
A Then B — Trigger when the address matches the value in comparator B but only after the address for
another cycle matched the value in comparator A. There can be any number of cycles after the A match
and before the B match.
A AND B Data (Full Mode) — This is called a Full Mode because address, data, and R/W (optionally)
must match within the same bus cycle to cause a trigger event. Comparator A checks address, the low byte
of comparator B checks data, and R/W is checked against RWA if RWAEN = 1. The high-order half of
comparator B is not used.
In Full Trigger Mode it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if
you do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and
the CPU breakpoint is issued when the comparator A address matches.
A AND NOT B Data (Full Mode) — Address must match comparator A, data must not match the low
half of comparator B, and R/W must match RWA if RWAEN = 1. All three conditions must be met within
the same bus cycle to cause a trigger.
In Full Trigger Mode it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if
you do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and
the CPU breakpoint is issued when the comparator A address matches.
Event-Only B (Store Data) — Trigger events occur each time the address matches the value in
comparator B. Trigger events cause the data to be captured into the FIFO. The debug run ends when the
FIFO becomes full.
A Then Event-Only B (Store Data) — After the address has matched the value in comparator A, a trigger
event occurs each time the address matches the value in comparator B. Trigger events cause the data to be
captured into the FIFO. The debug run ends when the FIFO becomes full.
Inside Range (A
≤ Address ≤ B) — A trigger occurs when the address is greater than or equal to the value
in comparator A and less than or equal to the value in comparator B at the same time.
Outside Range (Address < A or Address > B) — A trigger occurs when the address is either less than
the value in comparator A or greater than the value in comparator B.
21.3.6
Hardware Breakpoints
The BRKEN control bit in the DBGC register may be set to 1 to allow any of the trigger conditions
CPU. TAG in DBGC controls whether the breakpoint request will be treated as a tag-type breakpoint or a
force-type breakpoint. A tag breakpoint causes the current opcode to be marked as it enters the instruction
queue. If a tagged opcode reaches the end of the pipe, the CPU executes a BGND instruction to go to
Active Background Mode rather than executing the tagged opcode. A force-type breakpoint causes the
CPU to finish the current instruction and then go to Active Background Mode.
If the Background Mode has not been enabled (ENBDM = 1) by a serial WRITE_CONTROL command
through the BKGD pin, the CPU will execute an SWI instruction instead of going to Active Background
Mode.