CORO: Microprocessors, Microcontrollers & Embedded Systems

What is a microprocessor?

A microprocessor is the CPU/“brain” of a general-purpose computer, such as a personal computer (PC).

Why is a microprocessor sometimes called a “brain without a body”?

Because it mainly contains the processing unit but does not have built-in memory and I/O hardware. It needs to be connected to a motherboard and other components to function as a complete computer.

Think:

Microprocessor = Brain
Motherboard + memory + I/O = Body

What does I/O stand for?

Input/Output.

• Input = information going into the computer.

• Output = information coming out of the computer.

What type of tasks are microprocessors designed for?

General-purpose tasks, where one computer can perform many different jobs.

Examples:

• Writing documents

• Browsing the internet

• Playing music

• Running applications

• Watching videos

What is meant by a general-purpose computer?

A computer designed to perform many different types of tasks, rather than being built for only one specific job.

Example: A laptop can browse the internet, play games, edit documents, watch videos, etc.

What are transistors?

Transistors are tiny electronic switches inside processors and other electronic chips. They are used to process and control electrical signals.

How has the number of transistors in processors changed over time?

The number has increased enormously.

• 6502 processor (1975): about 3,510 transistors

• Modern Intel i7 CPU: about 2.6 billion transistors

Test tip: Remember the huge difference — 3,510 → billions.

Why are transistors important in a processor?

They act as tiny electronic switches that allow the processor to perform calculations and process information.

What is a microcontroller?

A microcontroller is a small computer on a single chip that contains a processor, memory and I/O hardware.

What is a microcontroller the “brain” of?

The brain of an embedded system.

What is the major difference between a microprocessor and a microcontroller?

Microprocessor	Microcontroller
Mainly the processing unit	Contains CPU + memory + I/O
Needs more external hardware	Has many components built in
Used for general-purpose computers	Often used in embedded systems
More powerful/flexible for general tasks	Designed for specific tasks

Memory trick:

MicroPROCESSOR → PROCESSING is the main thing

MicroCONTROLLER → CONTROLS a specific system

Why can a microcontroller be described as having more “intelligence straight out of the box”?

Because it already contains memory and I/O hardware on the same chip, allowing it to perform its intended tasks without requiring as much external hardware.

Is a microcontroller generally simpler than a modern PC microprocessor?

Yes. Microcontrollers are generally simpler and designed for specific control tasks.

What is an embedded system?

An embedded system is a piece of electronic circuitry/computer system designed to perform a specific job or set of related tasks.

What is the main characteristic of an embedded system?

It is designed for a specific purpose, rather than being a general-purpose computer.

Give examples of embedded systems.

• Smart TVs

• Wi-Fi routers

• 🍿 Microwaves

• MP3 players

• Digital cameras

• DStv decoders

• Modern cars

Why is a microwave an example of an embedded system?

Because its electronic system is designed primarily to control the microwave's specific functions, such as heating food, controlling time and responding to buttons/sensors.

Why is a Wi-Fi router an embedded system?

Because its circuitry is designed primarily to perform networking and communication tasks.

Do embedded systems normally run general-purpose software such as Microsoft Word or Excel?

No.

They normally run software designed specifically to control the device's functions.

How are embedded systems used in modern cars?

They can control many functions, including:

• GPS/navigation

• Headlights

• Sensors

• Engine systems

• Safety systems

• Entertainment systems

What is the difference between a microprocessor and an embedded system?

Microprocessor:
The processing component/CPU used mainly in general-purpose computers.

Embedded system:
A complete electronic system designed to perform a specific task.

What is the relationship between a microcontroller and an embedded system?

A microcontroller can act as the brain of an embedded system, controlling its inputs and outputs.

Example:

Temperature sensor → Microcontroller → Fan

Which is more likely to be found in a general-purpose PC: a microprocessor or microcontroller?

A microprocessor.

Which is more likely to be used to control a microwave: a microprocessor or microcontroller?

A microcontroller, because the microwave needs to perform specific control tasks.

What is an Arduino Uno?

The Arduino Uno is a popular microcontroller development board used by students, teachers, hobbyists and makers to create electronic projects.

What microcontroller does the Arduino Uno use?

The ATmega328P microcontroller.

How many bits is the Arduino Uno's ATmega microcontroller?

8-bit.

What is the “brain” of the Arduino Uno?

The ATmega microcontroller.

What is the purpose of the crystal oscillator on an Arduino Uno?

It provides the clock/timing signal needed for the microcontroller to operate.

The Arduino Uno uses a 16 MHz clock.

What does 16 MHz mean?

It means the clock operates at approximately 16 million cycles per second.

What is the purpose of the USB connector on an Arduino Uno?

It allows the Arduino to connect to a computer so that you can upload programs to it.

What is an Arduino program called?

A sketch.

What is the purpose of the power plug?

It allows the Arduino to receive power from an external power source, such as a battery or adapter.

Your notes specify:

6–20 V accepted
9 V recommended in Tinkercad

What are the digital I/O pins on the Arduino Uno?

Pins 0–13.

They can be used for digital input and output.

What are the analog input pins on the Arduino Uno?

A0–A5.

These are used to read analog signals from sensors and other devices.

What are the three main types of memory on the Arduino Uno?

1. Flash memory

2. SRAM

3. EEPROM

How much Flash memory does the Arduino Uno have?

32 KB

What is Flash memory used for?

It stores the program/sketch that the Arduino runs.

Is Flash memory volatile or non-volatile?

Non-volatile.

It keeps its information even when the power is turned off.

Flash = remembers

How much SRAM does the Arduino Uno have?

2 KB

What is SRAM used for?

It is used for variables and temporary data while the program is running.

Is SRAM volatile or non-volatile?

Volatile.

It loses its stored data when power is removed.

RAM = temporary

How much EEPROM does the Arduino Uno have?

1 KB

What is EEPROM used for?

It stores small amounts of data that need to remain saved even after the Arduino loses power.

Is EEPROM volatile or non-volatile?

Non-volatile.

What is the difference between Flash, SRAM and EEPROM?

Memory	Size	Main purpose	Power off?
Flash	32 KB	Stores program/sketch	Keeps data
SRAM	2 KB	Variables/temporary data	Loses data
EEPROM	1 KB	Small long-term data	Keeps data

Memorise this table. It is extremely testable.

What is the infinite loop in an embedded system?

It is a continuous cycle where the system repeatedly:

1. Reads the environment → 2. Processes information → 3. Takes action

Then it repeats.

What is Step 1 of the infinite loop?

Read the environment.

The system reads information from inputs and sensors.

Example:

A robot uses a distance sensor to determine how close it is to a wall.

What is Step 2 of the infinite loop?

Process information.

The program uses the input information to decide what should happen next.

What is Step 3 of the infinite loop?

Take action.

The system activates an output based on the processed information.

Give an example of the complete infinite loop using a robot.

Read: Distance sensor detects a wall.

Process: Microcontroller determines that the robot is too close.

Action: Motor stops or changes direction.

Repeat 🔄

Why is the process called an “infinite” loop?

Because the system continuously repeats the read → process → action cycle while it is operating.

What is an input?

An input is information or a signal that enters the system.

Examples:

• Button

• Switch

• Temperature sensor

• Distance sensor

• Light sensor

What is an output?

An output is an action or signal produced by the system.

Examples:

• LED turning on

• Motor moving

• Speaker producing sound

• Display showing information

What is the easiest way to remember input vs output?

INPUT = information IN

OUTPUT = action OUT

Is a button an input or an output?

Input.

The system reads whether the button has been pressed.

Is an LED an input or output?

Output.

The Arduino controls whether the LED turns on or off.

Is a temperature sensor an input or output?

Input.

It sends temperature information into the system.

Is a motor an input or output?

Usually an output, because the microcontroller controls the motor.

What is a digital signal?

A signal that has discrete states, commonly represented as:

ON / OFF

or

1 / 0

What are digital ports used for?

They are used with devices that can operate using digital states, such as ON/OFF.

Give examples of digital devices.

• Push button

• Basic switch

• Basic LED

A button is either pressed or not pressed. Is this digital or analog?

Digital.

It can be represented as two states:

Pressed = ON/1

Not pressed = OFF/0

An LED is either ON or OFF. Is this digital or analog?

Digital in this basic example.

What is an analog signal?

A signal that can have a range of different values, rather than only two states.

What is the difference between digital and analog?

Digital:
Limited/discrete states.

Example:

OFF → ON

0 → 1

Analog:
A range of values.

Example:

Low volume → medium volume → high volume

Give examples of analog inputs.

• Volume knob

• Temperature sensor

• Light sensor

• Potentiometer

Why is a volume knob an example of an analog input?

Because it can provide many different values, from very low volume to very high volume, rather than simply ON or OFF.

Why can a temperature sensor be considered an analog input?

Because temperature can vary across a continuous range of values, such as 18°C, 18.5°C, 19°C, 19.5°C, etc.

Can an output be controlled using different levels rather than simply ON/OFF?

Yes. A system can control an output across a range.

Example:

A drone motor can operate at different speeds rather than simply stopped/full speed.