SH7052 Datasheet, PDF (139/919 Pages) Renesas Technology Corp – SuperHTM RISC engine

7.5.3 Contention between User Break and Exception Processing
If a user break is set for the fetch of a particular instruction, and exception processing with higher
priority than a user break is in contention and is accepted in the decode stage for that instruction
(or the next instruction), user break exception processing may not be performed after completion
of the higher-priority exception service routine (on return by RTE).
Thus, if a user break condition is applied to the branch destination instruction fetch after a branch
(BRA, BRAF, BT, BF, BT/S, BF/S, BSR, BSRF, JMP, JSR, RTS, RTE, exception processing),
and that branch instruction accepts exception processing with higher priority than a user break
interrupt, user break exception processing is not performed after completion of the higher-priority
exception service routine.
Therefore, a user break condition should not be set for the fetch of the branch destination
instruction after a branch.
7.5.4 Break at Non-Delay Branch Instruction Jump Destination
When a branch instruction with no delay slot (including exception processing) jumps to the jump
destination instruction on execution of the branch, a user break will not be generated even if a user
break condition has been set for the first jump destination instruction fetch.
7.5.5 User Break Trigger Output
Information on internal bus condition matches monitored by the UBC is output as UBCTRG. The
trigger width can be set with clock select bits 1 and 0 (CKS1, CKS0) in the user break control
register (UBCR).
If a condition matches occurs again during trigger output, the UBCTRG pin continues to output a
low level, and outputs a pulse of the length set in bits CKS1 and CKS0 from the cycle in which the
last condition match occurs.
The trigger output conditions differ from those in the case of a user break interrupt when a CPU
instruction fetch condition is satisfied. When a condition occurs in an overrun fetch instruction as
described in section 7.5.2, Instruction Fetch at Branches, a user break interrupt is not requested but
a trigger is output from the UBCTRG pin.
In other CPU data accesses and DMAC bus cycles, pulse output is performed under conditions
similar to user break interrupt conditions.
Setting the user break interrupt disable (UBID) bit to 1 in UBCR enables trigger output to be
monitored externally without requesting a user break interrupt.
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