Page 16 - Embedded Microprocessor Systems Real World Design

System Design I

It has been said that if you do not know where you are going, you will not know
when you get there. Success experts tell us that the first step in achieving anything
is to establish a goal-to be debt free in one year or to pay off the car in six months.
Like most things in life, the process of designing an embedded microprocessor
system begins with a goal-the definition of the product. The product definition
describes what the product is to be and do. The product definition is the first
element in a process that is key to any successful electronics system design: docu-
mentation. The documentation describes what you are going to build and how you
are going to build it. It tells marketing people what product they will have to sell,
and it tells the engineering team how to implement that product. Since this book
is about embedded systems, it will focus on documenting embedded systems. The
development documents that I have found useful in designing embedded systems
are as follows:
Product Requirements: Describe what the product is.
Functional Requirements: Describe what the product must do.
Engineering Specification: Describes how the design will be implemented and
how the requirements will be met.
Hardware Specifications: Describe how specific hardware is designed.
Firmware Specifications: Describe how the firmware for specific processors will
be designed.
Test Specifications: Describe what must be tested and how to verify that the
system operates correctly.
Figure 1.1 shows how each of the documents relates to the overall design. The
embedded design process generally follows these steps:
Product requirements definition
Functional requirements definition
Processor selection
Hardware/software specifications

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