The Raspberry Pi

 A Raspberry Pi is a small, affordable, single-board computer developed by the Raspberry Pi Foundation in the UK. It was originally designed to promote teaching of basic computer science and programming in schools, but over time, it has become a powerful platform used worldwide. It is a flexible tool that can perform both everyday computer tasks and specialized electronics functions. Various Raspberry Pi computers are as shown below:

Clockwise from top: Pi 400, Pico, Zero 2W, Pi 5 and original Model B.

A Raspberry Pi can:

1. Act as a Basic Computer

• Browse the internet

• Watch videos and stream media

• Use office apps (LibreOffice, Google Docs)

• Program in Python, Java, C/C++, etc.

2. Control Electronic Devices

• Connect sensors, motors, relays, lights, and displays

• Monitor data (temperature, air quality, motion)

• Automate processes (e.g., smart irrigation, door locks)

3. Build IoT and Smart Systems

• Send sensor data to the cloud

• Create a smart home controller (lights, fans, cameras)

• Track real-time data (like animal or human movement)

4. Run Artificial Intelligence & Machine Learning (lightweight)

• Perform object recognition using a camera

• Detect people, gestures, or animals in images

• Use TensorFlow Lite or Edge AI for on-device processing

5. Power Creative Projects

• Make a retro gaming console

• Build interactive art or sound installations

• Control robots or drones

6. Act as a Server

• Web server (host your own website)

• File server (like Google Drive at home)

• Network firewall

 

Models of Raspberry Pi

Raspberry Pi makes computers in several different series:

1.The Flagship series

The "standard" Raspberry Pi models (e.g., Raspberry Pi 3, 4, and 5)

• Purpose: General computing, learning, and projects.

• Features:

  • Full Linux operating system

  • USB ports, HDMI, audio jack, Ethernet, Wi-Fi, Bluetooth

  • 40-pin GPIO header for electronics and sensors

• Size: Credit card-sized board

• Use Cases: Education, media centers, IoT devices, small servers, electronics prototyping

Model B indicates the presence of an Ethernet port. Model A indicates a lower-cost model in a smaller form factor with no Ethernet port, reduced RAM, and fewer USB ports to limit board height. There are also models A+ and B+, both are part of the flagship family, and the “+” in the name means they are improved versions of earlier Model A and B boards with better performance, power efficiency, and GPIO support.

Raspberry Pi 3 Model A+

Raspberry Pi 3 Model B

Raspberry Pi 3 Model B+

2.The Keyboard series

Like a Flagship Pi, but built into a keyboard.

• Purpose: All-in-one beginner computer

• Features:

  • Same internals as the Raspberry Pi 4

  • Built-in keyboard (no separate case needed)

  • Pre-installed Linux OS (Raspberry Pi OS)

• Use Cases: Teaching computing in classrooms, basic desktop use, coding, learning Linux

• Example: Raspberry Pi 400 as shown below.

Raspberry Pi 400

3. The Zero series

Smaller, cheaper, and lower-power version of the flagship models

• Purpose: Cost-effective, portable projects

• Features:

  • Minimal ports (micro-USB, mini-HDMI, etc.)

  • No Ethernet port (though some models have Wi-Fi)

  • Runs Linux

• Size: Tiny — about a third of a flagship Pi

• Use Cases: Wearables, compact robots, DIY sensors, lightweight IoT devices

Example: Raspberry Pi Zero 2 W

Raspberry Pi Zero 2 W

4. The Compute Module series

Designed for industrial and embedded systems

• Purpose: Custom products and embedded designs

• Features:

  • Same CPU and RAM as flagship models

  • No ports (no USB, HDMI, GPIO directly on board)

  • Connects to a custom carrier board (like a motherboard) that provides needed ports/pins

• Use Cases: Commercial products, smart devices, embedded controllers, industrial systems

Example: Compute Module 4 (CM4)

Compute Module 4 (CM4)

5. Pico series

It is a microcontroller, like an Arduino. (hence not a computer like the rest)

• Purpose: Real-time control, simple embedded tasks

• Features:

  • No Linux OS

  • Programs written in C or MicroPython

  • No Ethernet, Wi-Fi (unless added separately)

  • Flash binary code directly to onboard storage, in simple terms it means, installing a tiny program directly into the chip, so the Pico can do what you want every time it’s powered on without needing an operating system or SD card.

• Use Cases: Controlling motors, reading sensors, fast real-time logic (e.g., smart lights, timers)

Example: Raspberry Pi Pico W

Raspberry Pi Pico W

 

Raspberry Pi 4 Model B

The Raspberry Pi 4 Model B is a powerful single-board computer developed by the Raspberry Pi Foundation. It’s part of the flagship series and offers a big leap in performance compared to its predecessors, making it suitable for tasks ranging from learning programming to building embedded systems, servers, and smart devices.

Architecture of a Raspberry Pi 4 Model B

Raspberry Pi 4 Model B

The Raspberry Pi 4 Model B is a System-on-Chip (SoC) based computer. It brings together a processor, memory, storage, networking, and peripheral connections all on one compact board. Let’s get into its architecture:

1. Broadcom BCM2711 Processor (CPU + GPU)

• Quad-core Cortex-A72 (ARM v8, 64-bit), clocked at 1.5GHz

• Integrated VideoCore VI GPU for graphics and video processing

• Acts as the brain of the Pi, executing code and managing all system functions

2. RAM (Memory)

• Comes in variants: 2GB, 4GB, or 8GB LPDDR4-3200 SDRAM

• Memory is shared between CPU and GPU

• Temporarily stores data, running programs, and processes

3. MicroSD Card Slot

• Main storage location for operating system and user files

• Replaceable and bootable

• Acts like a hard drive, but smaller and solid-state

4. Networking Functionality

• Gigabit Ethernet: For fast, wired internet connection

• 2.4GHz / 5GHz Wi-Fi : Dual-band wireless connectivity

• Bluetooth 5.0: For connecting peripherals like headphones, keyboards, and sensors

5. USB Ports

• 2 × USB 3.0 ports: High-speed data transfer (e.g. external SSDs, USB cameras)

• 2 × USB 2.0 ports: For standard USB devices like mice, keyboards, and flash drives

6. USB-C Power Port (5V / 3A)

• Powers the Pi

• Supplies enough current for the board and any connected USB peripherals

• Important: Needs a good-quality 5V/3A power supply for stability

7. GPIO Header (40-pin General Purpose I/O)

• Lets you interface with electronics: LEDs, motors, sensors, etc.

• Includes power (3.3V/5V), ground, and multiple GPIO pins (digital I/O)

• Supports protocols like I2C, SPI, UART

40-pin GPIO(General Purpose Input Output) Header

8. MIPI CSI Camera Port (2-lane)

• Connects to the Raspberry Pi Camera Module

• High-speed video/image capture directly into the GPU for processing

9. MIPI DSI Display Port (2-lane)

• For connecting the official Pi touchscreen display

• Supports high-speed data communication to LCD displays

Official Pi Touchscreen display

10. 2 × Micro HDMI Ports

• Supports dual 4K monitors (up to 4Kp60 and 1080p60 simultaneously)

• Allows full graphical desktop experience and multimedia applications

11. 4-Pole Stereo Audio and Composite Video Jack

• Combines analog audio output and composite video output in one 3.5mm jack

• Can be connected to speakers, headphones, or older TVs

12. PoE HAT Header (Power over Ethernet Hardware Attached on Top).

• This setup allows the Pi to receive both electrical power and a network connection through a single Ethernet cable, simplifying wiring in networked or embedded installations.

• Useful for networked setups where power plugs are hard to reach.

A PoE-capable switch or injector is required for this feature to work.

It is important to use heat sinks in your Raspberry Pi. SoC may need heatsink especially when using 4K video or under heavy load. Heat sinks prevent thermal throttling, which occurs when the CPU temperature rises above about 80 °C, causing the Pi to automatically reduce (“throttle”) its clock speed to avoid overheating. The heat sink helps by increasing the surface area in contact with air, it pulls heat away from the chip more efficiently, keeping temperatures below the throttling threshold.

 

Comparing the Raspberry Pi 4 model B to the Raspberry Pi 5

Raspberry Pi 4 Model B

Raspberry Pi 5

Feature	Raspberry Pi 4 Model B	Raspberry Pi 5	Improvement
CPU	Quad-core Cortex-A72 @ 1.5GHz	Quad-core Cortex-A76 @ 2.4GHz	~2–3× faster CPU performance
Dual Camera/Display	1 × CSI, 1 × DSI	2 × CSI/DSI via shared FFC connectors	Connect 2 cameras or 2 displays natively
PCIe Support	None (internal only)	PCIe 2.0 x1 via FPC connector	Connect SSDs, AI accelerators, etc.
USB	2 × USB 3.0, 2 × USB 2.0	2 × USB 3.0, 2 × USB 2.0 + Real PCIe	Dedicated PCIe for faster peripherals
SD Card Speed	UHS-I	UHS-I (with improved controller)	Faster read/write
GPIO Compatibility	40-pin header	40-pin header (same layout)	Full backward compatibility
RAM Speed	LPDDR4	LPDDR4X-4267	Higher RAM bandwidth
Real-Time Clock (RTC)	Not included	Built-in (battery connector)	Keeps time when powered off
Networking	Gigabit Ethernet (via USB controller)	Native Gigabit Ethernet	Lower latency, better performance
Boot Options	microSD, USB	microSD, USB, PCIe, Network	More flexible boot methods
GPU	VideoCore VI	VideoCore VII	More powerful graphics + 4K at 60Hz on dual HDMI
Power Management	Less advanced	New RP1 southbridge with better PMIC	More stable and efficient
Form Factor	Standard Pi form	Nearly same (with changes in port placement)	Small adjustments, same footprint
Fan/Power Header	None	Separate 4-pin fan + power header	Software-controlled cooling
Thermal Performance	Gets hot under load	Better cooling design + optional fan header	Stays cooler, more consistent performance

Glossary 

PCIe stands for Peripheral Component Interconnect Express. PCIe is like a super-fast data highway that allows external hardware to "talk" directly to the processor, it is much faster than USB or GPIO.

The RP1 is a custom I/O controller chip designed by Raspberry Pi. It handles input/output (I/O) functions like: USB ports, ethernet, GPIO, cameras and displays (CSI/DSI), audio and SD card access. The RP1 offloads these tasks from the main CPU. That means faster, more reliable I/O performance, and support for more complex devices (like dual cameras or SSDs via PCIe).

PMIC stands for Power Management Integrated Circuit. It manages how power is distributed across the Pi—CPU, RAM, USB, camera modules, etc.

UHS-I stands for Ultra High Speed – Phase I, and it refers to a speed class for SD cards. It defines how fast data can be read from and written to the card

 

Safety Tips when handling the Raspberry Pi

1. Discharge Static First
   Touch a grounded object before handling the Pi to avoid damaging sensitive components with static electricity.

• Avoid touching any pins or chips directly—hold the Pi by the edges. Place the Pi on a non-metal, non-static surface while working.

2. Always Power Off Before Handling
   Unplug the power supply before connecting peripherals, sensors, or adjusting GPIO wiring.

3. Prevent Overheating
   Use a heatsink or fan to keep the Pi cool during intensive use. Overheating can throttle performance or reduce lifespan.

4. Use a Proper Power Supply
   Ensure you’re using a stable 5V/3A USB-C adapter—underpowered supplies can cause instability or boot issues.

5. Avoid Short Circuits
   Keep the Pi off metal surfaces and ensure GPIO connections are correct and insulated. Shorts can permanently damage the board.

6. Handle Ports with Care
   Gently plug and unplug USB, HDMI, and GPIO cables. Support the board to avoid stressing connectors.

7. Protect with a Case
   Use a non-metallic case to shield the Pi from dust, damage, and accidental shorts, while ensuring good airflow.

8. Safely Shut Down
   Always shut down via the OS before unplugging. Sudden power loss can corrupt the SD card and OS.

9. Keep Away from Liquids
   Liquids can short out components. If spilled, disconnect power immediately and let the board dry fully before use.

10. Label and Organize GPIO Wiring
    Label pins and wires to avoid miswiring, especially when working on complex circuits.

 

References

Raspberry Pi Hardware Documentation

Raspberry Pi 4 Model B Architecture

Raspberry Pi Touchscreen Review