SH7670 Datasheet, PDF (1100/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 25 User Break Controller (UBC)
25.3 Operation
25.3.1 Flow of the User Break Operation
The flow from setting of break conditions to user break interrupt exception handling is described
below:
1. The break address is set in a break address register (BAR). The masked address bits are set in a
break address mask register (BAMR). The break data is set in the break data register (BDR).
The masked data bits are set in the break data mask register (BDMR). The bus break
conditions are set in the break bus cycle register (BBR). Three control bit groups of BBR (C
bus cycle/I bus 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 to 00. The relevant break
control conditions are set in the bits of the break control register (BRCR). Make sure to set all
registers related to breaks before setting BBR, and branch after reading from the last written
register. The newly written register values become valid from the instruction at the branch
destination.
2. In the case where the break conditions are satisfied and the user break interrupt request is
enabled, the UBC sends a user break interrupt request to the INTC, sets the C bus condition
match flag (SCMFC) or I bus condition match flag (SCMFD) for the appropriate channel.
3. On receiving a user break interrupt request signal, the INTC determines its priority. Since the
user break interrupt has a priority level of 15, it is accepted when the priority level set in the
interrupt mask level bits (I3 to I0) of the status register (SR) is 14 or lower. If the I3 to I0 bits
are set to a priority level of 15, the user break interrupt is not accepted, but the conditions are
checked, and condition match flags are set if the conditions match. For details on ascertaining
the priority, see section 6, Interrupt Controller (INTC).
4. Condition match flags (SCMFC and SCMFD) can be used to check which condition has been
satisfied. Clear the condition match flags during the user break interrupt exception processing
routine. The interrupt occurs again if this operation is not performed.
5. There is a chance that the break set in channel 0 and the break set in channel 1 occur around
the same time. In this case, there will be only one user break request to the INTC, but these
two break channel match flags may both be set.
6. When selecting the I bus as the break condition, note as follows:
 Several bus masters, including the CPU, DMAC, A-DMAC (including F-DMAC), and E-
DMAC, are connected to the I bus. The UBC monitors bus cycles generated by the bus
master specified by BBR, and determines the condition match.
Rev. 1.00 Nov. 14, 2007 Page 1074 of 1262
REJ09B0437-0100