ARM9TDMI Signal Descriptions
ARM DDI0145B
Copyright © 1998, 1999 ARM Limited. All rights reserved.
A-3
A.2
Data memory interface signals
Table A-2 Data memory interface signals
Name
Direction
Description
DA[31:0]
Output
Data Address Bus. This is the processor data address bus. It changes when
GCLK
is
HIGH.
DABE
Input
Data Address Bus Enable. When LOW, this input puts the data address bus,
DA[31:0]
,
drivers into a high impedance state. This signal has the same effect on
DnTRANS
,
DLOCK
,
DMAS[1:0]
,
DnRW
, and
DnM[4:0]
. If
UNIEN
is HIGH this signal is
ignored.
DABORT
Input
Data Abort. This input allows the memory system to tell the processor that the
requested data memory access is not allowed.
DD[31:0]
Output
Data Output Bus. This output bus is used to transfer write data between the processor
and external memory. The output data will become valid during phase 1 and remain
valid through
GCLK
phase 2.
If UNIEN is LOW, this is a tristate output bus and is only driven during write cycles.
If UNIEN is HIGH, this bus is always driven.
DDBE
Input
Data Data Bus Enable. This is an input which, when LOW, puts the Data Data Bus
DD[31:0]
into a high impedance state. If
UNIEN
is HIGH this signal is ignored.
DDEN
Output
Data Data Bus Output Enabled. This signal indicates when the processor is
performing a write transfer on the Data Data Bus,
DD[31:0]
.
DDIN[31:0]
Input
Data Input Bus. This input is used to transfer load data between external memory and
the processor. It should be driven with the requested data by the end of
GCLK
phase
2.
DLOCK
Output
Data Lock. If HIGH at the end of
GCLK
phase 2, any data memory access in the
following cycle is locked, and the memory controller must wait until
DLOCK
goes
LOW before allowing another device to access memory.
DMAS[1:0]
Output
Data Memory Access Size. These outputs encode the size of a data memory access in
the following cycle. A word access is encoded as 10 (binary), a halfword access as 01,
and a byte access as 00. The encoding 11 is reserved.
DMORE
Output
Data More. If HIGH at the end of
GCLK
phase 2, the data memory access in the
following cycle will be directly followed by a sequential data memory access.
DnM[4:0]
Output
Data Mode. The processor mode within which the data memory access should be
performed.
Note that the data memory access mode may differ from the current processor mode.
Содержание ARM9TDMI
Страница 1: ...Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ARM9TDMI Technical Reference Manual ...
Страница 6: ...Contents vi Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 12: ...Preface xii Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 16: ...Introduction 1 4 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 22: ...Programmer s Model 2 6 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 36: ...ARM9TDMI Processor Core Memory Interface 3 14 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 54: ...ARM9TDMI Coprocessor Interface 4 18 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 110: ...Test Issues 6 6 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 138: ...ARM9TDMI AC Characteristics 8 20 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 150: ...ARM9TDMI Signal Descriptions A 12 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...
Страница 154: ...Index Index 4 Copyright 1998 1999 ARM Limited All rights reserved ARM DDI0145B ...