init-020
Preinitialization
Power/clock/reset
ramp sequence
Boot ROM
(OS independent)
Boot loader
(OS independent)
OS/application
Public Version
Initialization Overview
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26.1 Initialization Overview
This chapter provides an overview of the requirements for initializing the device from power on to firmware
execution. An overview of the overall initialization process is given, including hardware- and
software-related steps, a general overview of the boot ROM code operational requirements, and
behavioral expectations.
26.1.1 Terminology
•
Bootstrap: Initial software (SW) launched by the ROM code during the memory booting phase
•
Downloaded software: Initial software downloaded into the internal static RAM (SRAM) by the ROM
code during the peripheral booting phase
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eFuse: A one-time programmable memory location usually set at the factory
•
Flash loader: Downloaded software launched by the ROM code in preflashing. It also programs an
image in external memories.
•
GP device: General-purpose device
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Initial software: Software executed by any of the ROM code mechanisms (memory booting or
peripheral booting). Initial software is a generic term for bootstrap and downloaded software.
•
Memory booting: ROM code mechanism that consists of executing initial software from external
memory
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Peripheral booting: ROM code mechanism that consists of polling selected interfaces, downloading,
and executing initial software (in this case, downloaded software) in the internal RAM.
•
Permanent booting device: Memory device containing, by default, the image to be executed during the
booting sequence. It is the default memory booting device. The permanent booting device is used after
warm reset if no software booting configuration is programmed.
•
Preflashing: A specific case of peripheral booting where the ROM code mechanism is used to program
the external flash memory
•
ROM code: The on-chip software in ROM that implements booting
26.1.2 Initialization Process
is an overview of the initialization process and its steps:
•
Preinitialization
•
Power/clock/reset ramp sequence
•
Boot ROM
•
Boot loader
•
OS/application
Each step, up to OS/applications running, is explained in the following sections.
Figure 26-1. Initialization Process
The first two steps in the initialization process are hardware-oriented; however, they require understanding
of the process of configuring those system interface pins (balls on the device) that have
software-configurable functionality. This configuration is an essential part of chip configuration and is
application-dependent. This chapter refers to those pins and the associated configuration registers that
are vital for correct device initialization.
3510
Initialization
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated