Chapter 10 - Embedded Systems

Question 1

What are embedded systems?

Answer 1

Real computer systems that support the operation of a non-computer device

Examples include watches, automobiles, and TVs.

Question 2

How do embedded systems differ from general-purpose systems?

Answer 2

They are resource constrained, require deep hardware awareness, have critical signal timing, and have a fluid hardware-software partition.

Question 3

What are the categories of embedded hardware?

Answer 3

• Off-the-shelf
• Configurable
• Fully-Customized

Question 4

What is the most common type of off-the-shelf hardware?

Answer 4

Microcontroller

Question 5

Name two examples of microcontrollers.

Answer 5

• Motorola’s 68HC12
• Intel’s 8051

Question 6

What is the purpose of a watchdog timer?

Answer 6

To guard against system hangs by checking for liveness.

Question 7

What are systems-on-a-chip (SOCs)?

Answer 7

Full blown computer systems etched on a single die.

Question 8

What is a semi-custom SOC?

Answer 8

A chip fabricated when a suitable off-the-shelf SOC is unavailable, using pre-designed IP circuits.

Question 9

What are programmable logic devices (PLDs)?

Answer 9

Configurable devices where circuit behavior can be changed to suit application needs.

Question 10

How do PAL chips differ from PLA chips?

Answer 10

PAL chips have programmable AND gates connected to fixed OR gates, while PLA chips have programmable AND gates connected through programmable OR gates.

Question 11

What is an application-specific integrated circuit (ASIC)?

Answer 11

A chip designed from scratch to provide specific functionality.

Question 12

What are hardware definition languages (HDLs)?

Answer 12

Languages that help manage circuit complexity by expressing circuit logic in algorithmic terms.

Question 13

Name two popular HDLs.

Answer 13

• Verilog
• VHDL

Question 14

What is SystemC?

Answer 14

An extension of C++ for embedded systems design, including modeling events and concurrency.

Question 15

What are the phases of system development in SpecC?

Answer 15

• Specification
• Architecture
• Communication channels
• Implementation

Question 16

What is interrupt latency?

Answer 16

The time between the occurrence of an interrupt and the execution of the first instruction of the ISR.

Question 17

What is the difference between hard and soft real-time systems?

Answer 17

Hard real-time systems have strict timing constraints, while soft real-time systems have timing that is important but not critical.

Question 18

Why is memory footprint a critical concern in embedded systems?

Answer 18

A large operating system consumes memory and power, which are limited resources.

Question 19

What is the specification for standardized Unix that Embedded Linux adheres to?

Answer 19

IEEE 1003.1-2001, POSIX

Question 20

What is the typical development path for embedded systems?

Answer 20

It is rigorous and linear, requiring clear and complete functional requirements.

Question 21

What is bare metal programming?

Answer 21

Writing software for systems with no tool support.

Question 22

What are the main challenges in event handling for embedded systems?

Answer 22

Events can occur asynchronously and in any order, making testing difficult.

Question 23

What are the benefits of hardware-software codesign?

Answer 23

Reduces errors and accelerates time to market.

Question 24

List some popular embedded operating systems.

Answer 24

• Windows CE
• Windows XP Embedded
• QNX
• MS-DOS

Question 25

What is one way to improve accuracy in embedded software development?

Answer 25

Using formal languages like Z.

Question 26

What is the role of global variables in embedded programming?

Answer 26

Some programmers advocate for their use to improve performance, while others oppose it.