ARM9TDMI Signal Descriptions
ARM DDI0145B
Copyright © 1998, 1999 ARM Limited. All rights reserved.
A-11
nRESET
Input
Not Reset.
This is a level-sensitive input signal which is used to start the processor from a known address.
The ARM9TDMI processor asynchronously enters reset when
nRESET
goes LOW.
nWAIT
Input
Not Wait.
When a memory request cannot be processed in a single cycle, the ARM9TDMI can be made
to wait for a number of
GCLK
cycles by driving
nWAIT
LOW. Internally, the inverse of
nWAIT
is ORed with
GCLK
, and must only change when
GCLK
is HIGH. If
nWAIT
is not
used, it must be tied HIGH.
UNIEN
Input
Unidirectional Enable.
When HIGH, all ARM9TDMI outputs are permanently driven, (the state of
IABE
,
DABE
,
DDBE
and
TBE
is ignored). The
DDIN[31:0]
and
DD[31:0]
buses form a unidirectional data
bus.
When LOW, outputs can go tristate and the
DD[31:0]
bus is only driven during write cycles.
If
DD[31:0]
and
DDIN[31:0]
are wired together, they form a bidirectional data bus.
Table A-6 Miscellaneous signals (continued)
Name
Direction
Description
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 ...