Datasheet

Section 4 Address Break
Rev.5.00 Nov. 02, 2005 Page 66 of 500
REJ09B0027-0500
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.
NOP
instruc-
tion
prefetch
Register setting
• ABRKCR = H'80
• BAR = H'025A
Program
0258
025A
025C
0260
0262
:
*
NOP
NOP
MOV.W @H'025A,R0
NOP
NOP
:
0258
Address
bus
Interrupt
request
025A 025C 025E SP-2 SP-4
NOP
instruc-
tion
prefetch
MOV
instruc-
tion 1
prefetch
MOV
instruc-
tion 2
prefetch
Internal
processing
Stack save
Interrupt acceptance
Underline indicates the address
to be stacked.
When the address break is specified in instruction execution cycle
φ
Figure 4.2 Address Break Interrupt Operation Example (1)