ARM Cortex R4F - Manual (Page 19)

Preface
ARM DDI 0363E Copyright © 2009 ARM Limited. All rights reserved. xix
ID013010 Non-Confidential, Unrestricted Access
monospace Denotes text that you can enter at the keyboard, such as commands, file
and program names, and source code.
monospace Denotes a permitted abbreviation for a command or option. You can enter
the underlined text instead of the full command or option name.
monospace italic Denotes arguments to monospace text where the argument is to be
replaced by a specific value.
monospace bold
Denotes language keywords when used outside example code.
< and > Enclose replaceable terms for assembler syntax where they appear in code
or code fragments. For example:
MRC p15, 0 <Rd>, <CRn>, <CRm>, <Opcode_2>
Timing diagrams
The figure named Key to timing diagram conventions explains the components used in timing
diagrams. Variations, when they occur, have clear labels. You must not assume any timing
information that is not explicit in the diagrams.
Shaded bus and signal areas are undefined, so the bus or signal can assume any value within the
shaded area at that time. The actual level is unimportant and does not affect normal operation.
Key to timing diagram conventions
Signals
The signal conventions are:
Signal level The level of an asserted signal depends on whether the signal is
active-HIGH or active-LOW. Asserted means:
•
HIGH for active-HIGH signals
• LOW for active-LOW signals.
Lower-case n At the start or end of a signal name denotes an active-LOW signal.
Prefix A Denotes global Advanced eXtensible Interface (AXI) signals.
Prefix AR Denotes AXI read address channel signals.
Prefix AW Denotes AXI write address channel signals.
Prefix B Denotes AXI write response channel signals.
Prefix P Denotes Advanced Peripheral Bus (APB) signals.
Clock
HIGH to LOW
Transient
HIGH/LOW to HIGH
Bus stable
Bus to high impedance
Bus change
High impedance to stable bus