SH7729R Datasheet, PDF (261/855 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer Super RISC engine Family/SH7700 Series

8.3 Operation Description
8.3.1 Flow of the User Break Operation
The flow from setting of break conditions to user break exception processing is described below:
1. The break addresses and the corresponding ASIDs are loaded in the break address registers
(BARA and BARB) and break ASID registers (BASRA and BASRB in CCN). The masked
addresses are set in the break address mask registers (BAMRA and BAMRB). The break data
is set in the break data register (BDRB). The masked data is set in the break data mask register
(BDMRB). The breaking bus conditions are set in the break bus cycle registers (BBRA and
BBRB). Three groups of the BBRA and BBRB (CPU cycle/DMAC cycle select, instruction
fetch/data access select, and read/write select) are each set. No user break will be generated if
even one of these groups is set with 00. The respective conditions are set in the bits of BRCR.
2. When the break conditions are satisfied, the UBC sends a user break request to the interrupt
controller. The break type will be sent to the CPU indicating instruction fetch, pre/post
instruction break, data access break, or on-chip I/O access/LDTLB break. When conditions
match, the CPU condition match flags (SCMFCA and SCMFCB) and DMAC condition match
flags (SCMFDA and SCMFDB) for the respective channels are set.
3. The appropriate condition match flags (SCMFCA, SCMFDA, SCMFCB, and SCMFDB) can
be used to check if the set conditions match or not. The matching of the conditions sets flags,
but they are not reset. 0 must first be written to them before they can be used again.
4. There is a chance that a data access break and its following instruction fetch break will occur
around the same time; there will be only one break request to the CPU, but these two break
channel match flags could be both set.
8.3.2 Break on Instruction Fetch Cycle
1. When CPU/instruction fetch/read/word or longword is set in the break bus cycle registers
(BBRA/BBRB), the break condition becomes the CPU instruction fetch cycle. Whether it then
breaks before or after execution of the instruction can then be selected with the PCBA/PCBB
bits in the break control register (BRCR) for the appropriate channel.
2. An instruction set for a break before execution breaks when it is confirmed that the instruction
has been fetched and will be executed. This means this feature cannot be used on instructions
fetched by overrun (instructions fetched at a branch or during an interrupt transition, but not to
be executed). When this kind of break is set for the delay slot of a delay branch instruction, the
break is generated prior to execution of the instruction that then first accepts the break.
Meanwhile, breaks set for pre-instruction-break on a delay slot instruction and post-
instruction-break on a SLEEP instruction are also prohibited.
Rev. 5.0, 09/03, page 215 of 806