RAM 6.0 BUX II Series Guia do Utilizador descarregar pdf (Página 11)

1 Introduction

1.3 BSP Development Process

Wind River provides processor-dependent software as part of each reference BSP.

That is, the portions of the BSP that depend only on processor type are done for

you. In addition, many hardware drivers are available for each processor type. You

can often use these drivers without change or, in most other cases, you can easily

modify the drivers to suit specific hardware.

1.3 BSP Development Process

In order to create a functioning BSP, the BSP writer must pass through several

stages of BSP development. Briefly, these stages include:

■

configuring the development environment

■

minimal hardware or hardware simulator configuration

■

gaining a clear understanding of the hardware

■

creating a minimal, functioning kernel

■

BSP cleanup and the addition of device drivers

Configuration of the development environment includes choosing, installing, and

configuring a compiler, debugger, and other tools.You must also determine what

download mechanism(s) to use, including how to program ROM or flash devices,

and which hardware debugger to use, if any.

The first step of actual development is writing software to initialize the hardware

to a quiescent state. That is, bringing the hardware to a state where it does not

generate interrupts that the processor is unable to handle at this point during the

system initialization process. Quiescent initialization code is usually created in

assembly language and is typically a short piece of code. Additional code is

necessary to reach the point where VxWorks is running. Most of this additional

code is written in a higher-level language, such as C.

The amount of time required to bring a BSP to the point that VxWorks is running

with just clock, serial, and Ethernet drivers varies greatly. In part, the amount of

time depends on how close the reference BSP is to the target hardware, as well as

the choice of development environment. It may also depend on what boot

configurations are supported. If a hardware debugger, such as the Wind River ICE

emulator, is available for debugging and flash programming, if a relatively similar

reference BSP is available, and if all normal boot configurations are supported, the

BSP development process can take as little as five to six weeks for an experienced

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RAM 6.0 BUX II Series Guia do Utilizador Página 11