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Figure 4-1. Software-Initiated Reset Request Overview
C h ip R eset C o n t ro ls
ac _ an _ reset _w d _ req u est
ac _ an _reset _1_ req u est
ac _ an _reset _2_ req u est
ac _ an _reset _3_ req u est
an _ac _ reset _1 _co m p let e
an _ac _reset _2_ co m p let e
an _ac _ reset _3 _co m p let e
an _ac _ reset _w d _ co m p let e
SC O M In t erf ace
4.4 Initialization Software Requirements
After a reset operation occurs, the A2 core is initialized to a minimum configuration to enable the fetching and
execution of the software initialization code and to guarantee deterministic behavior of the core during the
execution of this code. Initialization software is necessary to complete the configuration of the processor core
and the rest of the on-chip and off-chip system.
The system must provide nonvolatile memory (or memory initialized by some mechanism other than the A2
core) at the real address corresponding to the initial effective address that is scanned into the boot configura-
tion ring during hardware reset, and at the rest of the initial program memory page. The instruction at the
initial address must be an unconditional branch backwards to the beginning of the initialization software
sequence.
The initialization software functions described in this section perform the configuration tasks required to
prepare the A2 core to boot an operating system and subsequently execute an application program.
The initialization software must also perform functions associated with hardware resources that are outside
the A2 core, and hence that are beyond the scope of this manual. This section refers to some of these func-
tions, but their full scope is described in the user's manual for the specific chip and/or system implementation.
Initialization software should perform the following tasks to fully configure the A2 core. For more information
about the various functions referenced in the initialization sequence, see the corresponding chapters of this
document.
1. Branch backwards from the initial effective address (which is scanned into the instruction address register
from the boot configuration ring during hardware reset) to the start of the initialization sequence.
Version 1.3
October 23, 2012
A 2 C o re
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W at ch d o g T im er F u n ct io n
( W D T R eset Erro rs t o F IR )
W at c h d o g T im e r
T C R [ W R C]
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D e b u g C t rl 0
D B C R0 [R S T ]
(p e r th re a d)
D e b u g S t a tu s
D B S R[ M R R]
( p e r th re a d)
T im e r S t a t u s
T S R[W R S]
(p e r th re a d)
User's Manual
A2 Processor
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Sat ellit e
Initialization
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