1) What is an Embedded System?
How is it different from a General-
Purpose System?
Embedded System: A combination of hardware and software (firmware)
designed to perform a specific function.
Example: Washing machine, ATM, microwave oven.
🆚 Difference:
General-
Feature Embedded System Purpose
System
Multiple
Purpose Specific task only
tasks
OS May or may not have Always has
User can
Flexibility Fixed program install
programs
Faster is
Speed Priority Depends on task
better
Not always
Power Saving Highly optimized
optimized
2) History and Classification of Embedded Systems
📜 History:
Started before IT revolution with vacuum tubes and transistors.
First modern system: Apollo Guidance Computer (NASA).
First mass-produced: Autonetics D-17 (1961).
🔢 Classification:
1. Based on Generation:
o 1st: 8-bit, simple (e.g., keypad)
o 2nd: 16-bit (e.g., SCADA)
o 3rd: 32-bit + DSPs, OS support
o 4th: SoC, reconfigurable
o 5th (Next): AI, IoT-enabled
2. Based on Complexity:
o Small (e.g., toys)
o Medium (e.g., cameras)
o Large (e.g., spacecraft)
3. Based on Behavior:
o Deterministic: Predictable
o Non-deterministic: Flexible
4. Based on Triggering:
o Event-triggered: Alarm rings when triggered
o Time-triggered: Happens at fixed time (e.g., irrigation)
3) Purpose of Embedded Systems (with examples)
Function Example
Digital
Data Collection
camera
Router,
Data Communication network
switch
Signal Processing Hearing aid
Monitoring ECG machine
Air
Control
conditioner
Mobile phone
User Interface
keypad
4) Core of Embedded System and Categories
The core is the brain of an embedded system.
🔸 Types of Cores:
1. Processors/Controllers:
o Microprocessors (CPU only)
o Microcontrollers (CPU + memory + I/O)
o Digital Signal Processors (DSP)
2. ASICs – Application-specific
3. PLDs – Programmable Logic Devices
5) Difference between Microprocessor and Microcontroller
Microcontrol
Feature Microprocessor
ler
CPU + RAM +
Components CPU only
ROM + I/O
Dependency Needs external chips Self-contained
Cost Costly Cheap
High-performance Embedded
Use
tasks applications
Power Saving Low High
6) Short Note on Digital Signal Processors (DSP)
DSPs are special processors for audio, video, communication.
Faster than regular CPUs for signal tasks.
Used in hearing aids, music players, telecom devices.
Key Features:
Program memory + Data memory
Fast real-time processing
Specialized ALUs and shifters
7) Difference between RISC and CISC
Feature RISC CISC
Complex
Reduced Instruction
Full Form Instruction
Set
Set
Many,
Instructions Few, simple
complex
Speed Fast (pipelining) Slower
Code Length Longer Shorter
Example ARM 8051
8) Difference between Harvard and Von Neumann Architectures
Von
Feature Harvard Neuma
nn
Separate for code Single
Memory
and data memory
One
Bus Two (parallel)
(shared)
Speed Fast Slower
Cost Costly Cheaper
Intel
Example DSP
8086
9) Difference between Big Endian and Little Endian
Exampl
Format Description
e
Big High byte at low Motorol
Endian address a
Little Low byte at low
Intel
Endian address
Think of it like storing digits of a number:
Big Endian = 1234 (stored as 12 → 34)
Little Endian = 1234 (stored as 34 → 12)
10) Different Communication Interfaces in Microcontrollers
1. Internal (Onboard) – Used between chips inside a PCB:
I2C (Inter-Integrated Circuit)
SPI (Serial Peripheral Interface)
UART (Universal Asynchronous Receiver Transmitter)
2. External (Outside devices) – Used with other systems:
USB
Bluetooth
ZigBee
Wi-Fi
RS-232
11) Short Note on Passive Components and PCB
PCB (Printed Circuit Board): Base for mounting all components and
wiring.
Used for power flow and data flow.
🧩 Passive Components:
Compone
Function
nt
Resistor Controls current
Capacitor Stores electric charge
Allows current in one direction
Diode
only
These support the working of the main ICs.
✅ Short Note on Embedded Firmware
🔹 What is Firmware?
Firmware is a set of instructions or code written to control the hardware
in an embedded system. It’s like the “brain” of the device that tells it how to
behave.
🔹 Where is it Stored?
Stored in non-volatile memory like ROM, EEPROM, or Flash memory.
Unlike normal software, it is not meant to be changed frequently.
🔹 Why is it Important?
It directly controls sensors, actuators, displays, and other components.
Without firmware, the hardware cannot function.
🔹 Example:
In a microwave oven, firmware decides:
o What happens when you press a button
o How long to heat food
o How to control the display and beeps
✅ Embedded System Design Process Requirements
The design process involves planning, designing, and testing the
embedded system before actual development.
🔷 1. Requirement Analysis
Understand what the system must do.
Define functional (what it does) and non-functional (performance,
cost, power) requirements.
🔷 2. System Specification
Define hardware and software components.
Example: OS type, sensors used, memory size.
🔷 3. Hardware Design
Choose:
o Microcontroller/microprocessor
o I/O interfaces
o PCB design
o Power supply
🔷 4. Firmware Design
Develop the embedded software using C or assembly.
Includes device drivers, control algorithms, interrupt handling, etc.
🔷 5. Integration & Testing
Combine hardware + firmware.
Test the full system using simulators and debuggers.
🔷 6. Debugging and Optimization
Remove bugs and improve:
o Speed
o Memory use
o Power consumption
🔷 7. Final Deployment
Program firmware into final product.
Test for real-world conditions.
Release for use.
🎯 Summary:
Firmware is the control software stored inside embedded devices.
The design process ensures the system is built correctly — from
concept to working product.
