7.2.3
Break Bus Cycle Register A (BBRA)
Break bus cycle register A (BBRA) is a 16-bit read/write register, which specifies (1) CPU cycle
or DMAC cycle, (2) instruction fetch or data access, (3) read or write, and (4) operand size in the
break conditions of channel A. A power-on reset initializes BBRA to H'0000.
Bit:
15
—
0
14
—
0
13
—
0
12
—
0
11
—
0
10
—
0
9
—
0
8
—
0
Initial value:
R/W:
R
R
R
R
R
R
R
R
Bit:
7
CDA1
0
6
CDA0
0
5
IDA1
0
4
IDA0
0
3
2
1
SZA1
0
0
SZA0
0
RWA1 RWA0
Initial value:
R/W:
0
0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bits 15 to 8—Reserved: These bits are always read as 0. The write value should always be 0.
Bits 7 and 6—CPU Cycle/DMAC Cycle Select A (CDA1, CDA0): Selects the CPU cycle or
DMAC cycle as the bus cycle of the channel A break condition.
Bit 7: CDA1
Bit 6: CDA0
Description
0
0
1
0
Condition comparison is not performed
The break condition is the CPU cycle
The break condition is the DMAC cycle
(Initial value)
*
1
*: Don’t care
Bits 5 and 4—Instruction Fetch/Data Access Select A (IDA1, IDA0): Selects the instruction
fetch cycle or data access cycle as the bus cycle of the channel A break condition.
Bit 5: IDA1
Bit 4: IDA0
Description
0
0
1
0
1
Condition comparison is not performed
The break condition is the instruction fetch cycle
The break condition is the data access cycle
(Initial value)
1
The break condition is the instruction fetch cycle or data access
cycle
Rev. 5.00, 09/03, page 154 of 760
RENESAS [ RENESAS TECHNOLOGY CORP ]
