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CHAPTER 12 NBD FUNCTION (
μ
PD70F3116)
634
User’s Manual U14492EJ5V0UD
12.5 Control Registers
(1) RAM access data buffer register L (NBDL)
The NBDL register operates as the buffer between the DMA controller and the NBD tool when reading or
writing RAM from the NBD tool via the DMA controller.
This register can be read/written in 16-bit units.
When the higher 8 bits of the NBDL register are used as the NBDLU register, and the lower 8 bits are used
as the NBDLL register, they can be read/written in 8-bit units.
14
13
12
6
7
8
9
10
11
15
D14
D13
D12
2
D2
3
D3
4
D4
5
D5
D6
D7
D8
D9
D10
D11
D15
1
D1
0
D0
NBDL
Address
FFFFFA60H
Initial value
0000H
Cautions 1. Although the NBDL, NBDLU, and NBDLL registers can be used for reading or writing,
physically separate registers are used when reading and when writing, so written values
cannot be read.
2. Use both the NBDL and NBDH registers (refer to 12.5 (2)) for 32-bit access of RAM.
Remark
Register values written from the NBD tool can be read by DMA (CPU) and values written by DMA
(CPU) can be read by the NBD tool.
(2) RAM access data buffer register H (NBDH)
The NBDH register operates as the buffer between the DMA controller and the NBD tool when reading or
writing RAM from the NBD tool via the DMA controller.
This register can be read/written in 16-bit units.
When the higher 8 bits of the NBDH register are used as the NBDHU register, and the lower 8 bits are used
as the NBDHL register, they can be read/written in 8-bit units.
14
D30
13
D29
12
D28
2
D18
3
D19
4
D20
5
D21
6
D22
7
D23
8
D24
9
D25
10
D26
11
D27
15
D31
1
D17
0
D16
NBDH
Address
FFFFFA62H
Initial value
0000H
Cautions 1. Although the NBDH, NBDHU, and NBDHL registers can be used for reading or writing,
physically separate registers are used when reading and when writing, so written values
cannot be read.
2. Use both the NBDL and NBDH registers (refer to 12.5 (1)) for 32-bit access of RAM.
Remark
Register values written from the NBD tool can be read by DMA (CPU) and values written by DMA
(CPU) can be read by the NBD tool.