SH7046 Datasheet, PDF (147/611 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7046 Series

Section 7 User Break Controller (UBC)
If data accesses are also included in break conditions besides instruction fetch, a break will occur
because the instruction overrun fetch is also regarded as satisfying the data break condition.
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 specified 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 an exception processing with higher priority than a
user break interrupt, user break exception processing is not performed after completion of the
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 without delay slot (including exception processing) jumps to the
destination instruction by executing 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 match 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 match 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.
Rev. 4.00 Dec 05, 2005 page 103 of 564
REJ09B0270-0400