HD64F3687HV Datasheet, PDF (100/538 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Tiny Series

Section 4 Address Break
4.1.4 Break Data Registers (BDRH, BDRL)
BDRH and BDRL are 16-bit read/write registers that set the data for generating an address break
interrupt. BDRH is compared with the upper 8-bit data bus. BDRL is compared with the lower 8-
bit data bus. When memory or registers are accessed by byte, the upper 8-bit data bus is used for
even and odd addresses in the data transmission. Therefore, comparison data must be set in
BDRH for byte access. For word access, the data bus used depends on the address. See section
4.1.1, Address Break Control Register (ABRKCR), for details. The initial value of this register is
undefined.
4.2 Operation
When the ABIF and ABIE bits in ABRKSR are set to 1, the address break function generates an
interrupt request to the CPU. The ABIF bit in ABRKSR is set to 1 by the combination of the
address set in BAR, the data set in BDR, and the conditions set in ABRKCR. When the interrupt
request is accepted, interrupt exception handling starts after the instruction being executed ends.
The address break interrupt is not masked by the I bit in CCR of the CPU.
Figures 4.2 show the operation examples of the address break interrupt setting.
When the address break is specified in instruction execution cycle
Register setting
• ABRKCR = H'80
• BAR = H'025A
Program
0258 NOP
* 025A NOP
025C MOV.W @H'025A,R0
0260 NOP
0262 NOP
:
:
Underline indicates the address
to be stacked.
NOP NOP MOV MOV
instruc- instruc- instruc- instruc-
tion
tion tion 1 tion 2 Internal
prefetch prefetch prefetch prefetch processing
Stack save
φ
Address
bus
Interrupt
request
0258 025A 025C 025E
Interrupt acceptance
SP-2 SP-4
Figure 4.2 Address Break Interrupt Operation Example (1)
Rev.5.00 Nov. 02, 2005 Page 66 of 500
REJ09B0027-0500