BSP Developer's Guide

VxWorks 5.5
BSP Developer’s Guide
5.5 Step by Step
The general order shall be to design from the top down, but to implement and test
from the bottom-up.
Top-Down Design
Top-down design means planning and documenting before starting any actual
coding.
■
Template File
Start from a template file or an existing driver. A template file is preferred.
Starting from an existing file usually brings in all the problems of the other
driver code. Wind River provides template files for all classes of drivers.
■
Module Description
Find the chip manual and copy the introductory description of the chip into
the module description body. Then, add paragraphs detailing how this driver
is to work, which parts of the chip will be controlled, and the operating modes
that will be supported.
■
Device Structures
Start by defining a basic per-device data structure and a per-driver data
structure. These structures define the state of the driver and each device. As
structures, the debugger can display the complete state of either with a single
print command.
■
Macro Definitions
Document any macros that can be used to customize the driver for different
applications, such as chip access macros, memory access macros, and the like.
Tell the user what the macros do and how they are defined for the default
situation.
■
Subroutine Declarations
Declare all the subroutines you think the customer and BSP writer need to use
this driver. Try to follow the device design with the software design as much
as possible.
■
Block Out Functions
Create the banners and declarations for all the routines you plan to write.
Leave the bodies empty until you are really ready to write code. Write the
subroutine description in the comment block. The comments in the comment
100