What is Raspberry Pi?

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The Raspberry Pi is a low-cost, credit-card-sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing and to learn how to program in languages like Scratch and Python.

Raspberry Pi Foundation

The Raspberry Pi Foundation is a registered educational charity (registration number 1129409) based in the UK.


  • The Raspberry Pi Zero, a US$7 model first introduced in 2015
  • The Raspberry Pi 3 B+, introduced in 2018
  • The Raspberry Pi 4 B, introduced in 2019
  • The Raspberry Pi Pico, introduced in 2021

Several generations of Raspberry Pis have been released. Raspberry Pi SBCs feature a Broadcom system on a chip (SoC) with an integrated ARM-compatible central processing unit (CPU) and on-chip graphics processing unit (GPU), while Raspberry Pi Pico has an RP2040 system on chip with an integrated ARM-compatible central processing unit (CPU).

The first generation (Raspberry Pi Model B) was released in February 2012, followed by the simpler and cheaper Model A. In 2014, the Foundation released a board with an improved design, Raspberry Pi Model B+. These first-generation boards feature ARM11 processors, are approximately credit-card sized, and represent the standard mainline form-factor. Improved A+ and B+ models were released a year later.[clarification needed] A “Compute Module” was released in April 2014 for embedded applications.

The Raspberry Pi 2 was released in February 2015 and initially featured a 900 MHz 32-bit quad-core ARM Cortex-A7 processor with 1 GiB RAM. Later versions featured a 1.2 GHz 64-bit quad-core ARM Cortex-A53 processor.

A Raspberry Pi Zero with a smaller size and reduced input/output (I/O) and general-purpose input/output (GPIO) capabilities was released in November 2015 for US$5. On 28 February 2017, the Raspberry Pi Zero W was launched, a version of the Zero with Wi-Fi and Bluetooth capabilities, for US$10.On 12 January 2018, the Raspberry Pi Zero WH was launched, a version of the Zero W with pre-soldered GPIO headers.

Raspberry Pi 3 Model B was released in February 2016 with a 1.2 GHz 64-bit quad-core ARM Cortex-A53 processor, onboard 802.11n Wi-Fi, Bluetooth, and USB boot capabilities.[30] On Pi Day 2018, the Raspberry Pi 3 Model B+ was launched with a faster 1.4 GHz processor, a three-times faster gigabit Ethernet (throughput limited to ca. 300 Mbit/s by the internal USB 2.0 connection), and 2.4 / 5 GHz dual-band 802.11ac Wi-Fi (100 Mbit/s). Other features are Power over Ethernet (PoE) (with the add-on PoE HAT), USB boot, and network boot (an SD card is no longer required).

Raspberry Pi 4 Model B was released in June 2019[2] with a 1.5 GHz 64-bit quad-core ARM Cortex-A72 processor, on-board 802.11ac Wi-Fi, Bluetooth 5, full gigabit Ethernet (throughput not limited), two USB 2.0 ports, two USB 3.0 ports, and dual-monitor support via a pair of micro HDMI (HDMI Type D) ports for up to 4K resolution. The Pi 4 is also powered via a USB-C port, enabling additional power to be provided to downstream peripherals, when used with an appropriate PSU. The initial Raspberry Pi 4 board has a design flaw where third-party e-marked USB cables, such as those used on Apple MacBooks, incorrectly identify it and refuse to provide power. Tom’s Hardware tested 14 different cables and found that 11 of them turned on and powered the Pi without issue. The design flaw was fixed in revision 1.2 of the board, released in late 2019.

Raspberry Pi 400 Kit

Raspberry Pi 400 was released in November 2020. It features a custom board that is derived from the existing Raspberry Pi 4, specifically remodeled with a keyboard attached. A robust cooling solution similar to the one found in a Commodore 64 allows the Raspberry Pi 400’s Broadcom BCM2711C0 processor to be clocked at 1.8 GHz, which is slightly higher than the Raspberry Pi 4 it’s based on. The keyboard-computer features 4 GiB of LPDDR4 RAM.

Raspberry Pi Pico was released in January 2021 with a retail price of $4. It was Raspberry Pi’s first board based upon a single microcontroller chip; the RP2040, which was designed by Raspberry Pi in the UK. The Pico has 264 KiB of RAM and 2 MiB of flash memory. It is programmable in MicroPython, CircuitPython, and C. It has partnered with Adafruit, Pimoroni, Arduino, and Sparkfun to build Accessories for Raspberry Pi Pico and a variety of other boards using RP2040 Silicon Platform. Rather than perform the role of general-purpose computer (like the others in the range) it is designed for physical computing, similar in concept to an Arduino[40]


The Raspberry Pi hardware has evolved through several versions that feature variations in the type of the central processing unit, amount of memory capacity, networking support, and peripheral-device support.


This block diagram describes models B, B+, A, and A+. The Pi Zero models are similar but lack the Ethernet and USB hub components. The Ethernet adapter is internally connected to an additional USB port. In Model A, A+, and the Pi Zero, the USB port is connected directly to the system on a chip (SoC). On the Pi 1 Model B+ and later models, the USB/Ethernet chip contains a five-port USB hub, of which four ports are available, while the Pi 1 Model B only provides two. On the Pi Zero, the USB port is also connected directly to the SoC, but it uses a micro USB (OTG) port. Unlike all other Pi models, the 40 pin GPIO connector is omitted on the Pi Zero, with solderable through-holes only in the pin locations. The Pi Zero WH remedies this.

Processor speed ranges from 700 MHz to 1.4 GHz for the Pi 3 Model B+ or 1.5 GHz for the Pi 4; on-board memory ranges from 256 MiB to 1 GiB random-access memory (RAM), with up to 8 GiB available on the Pi 4. Secure Digital (SD) cards in MicroSDHC form factor (SDHC on early models) are used to store the operating system and program memory. The boards have one to five USB ports. For video output, HDMI and composite video are supported, with a standard 3.5 mm tip-ring-sleeve jack for audio output. Lower-level output is provided by several GPIO pins, which support common protocols like I²C. The B-models have an 8P8C Ethernet port and the Pi 3, Pi 4, and Pi Zero W have on-board Wi-Fi 802.11n and Bluetooth.


The Raspberry Pi 2B uses a 32-bit 900 MHz quad-core ARM Cortex-A7 processor.

The Broadcom BCM2835 SoC used in the first generation Raspberry Pi includes a 700 MHz ARM1176JZF-S processor, VideoCore IV graphics processing unit (GPU), and RAM. It has a level 1 (L1) cache of 16 KiB and a level 2 (L2) cache of 128 KiB. The level 2 cache is used primarily by the GPU. The SoC is stacked underneath the RAM chip, so only its edge is visible. The ARM1176JZ(F)-S is the same CPU used in the original iPhone, although at a higher clock rate, and mated with a much faster GPU.

The earlier V1.1 model of the Raspberry Pi 2 used a Broadcom BCM2836 SoC with a 900 MHz 32-bit, quad-core ARM Cortex-A7 processor, with 256 KiB shared L2 cache. The Raspberry Pi 2 V1.2 was upgraded to a Broadcom BCM2837 SoC with a 1.2 GHz 64-bit quad-core ARM Cortex-A53 processor, the same SoC which is used on the Raspberry Pi 3, but underclocked (by default) to the same 900 MHz CPU clock speed as the V1.1. The BCM2836 SoC is no longer in production as of late 2016.

The Raspberry Pi 3 Model B uses a Broadcom BCM2837 SoC with a 1.2 GHz 64-bit quad-core ARM Cortex-A53 processor, with a 512 KiB shared L2 cache. The Model A+ and B+ are 1.4 GHz.

The Raspberry Pi 4 uses a Broadcom BCM2711 SoC with a 1.5 GHz 64-bit quad-core ARM Cortex-A72 processor, with 1 MiB shared L2 cache. Unlike previous models, which all used a custom interrupt controller poorly suited for virtualization, the interrupt controller on this SoC is compatible with the ARM Generic Interrupt Controller (GIC) architecture 2.0, providing hardware support for interrupt distribution when using ARM virtualization capabilities.

The Raspberry Pi Zero and Zero W use the same Broadcom BCM2835 SoC as the first generation Raspberry Pi, although now running at 1 GHz CPU clock speed.

The Raspberry Pi Pico uses the RP2040 running at 133 MHz.

Applications of Raspberry Pi

The raspberry pi boards are used in many applications like Media streamer, Arcade machine, Tablet computer, Home automation, Carputer, Internet radio, Controlling robots, Cosmic Computer, Hunting for meteorites, Coffee, and also in raspberry pi based projects.

Raspberry Pi based Motor Speed Control

The main intention of this project is to control the speed of a DC Motor using Raspberry Pi.

Hardware and Software Requirements

DC Motor, Raspberry pi model, TV or PC monitor, Motor Driver IC, LED, Resistors, Capacitors, Diode, Transformer, Voltage Regulator.

This project uses a Raspberry Pi board to control the DC motor speed. The speed of a DC motor is directly proportional to the voltage applied across its terminals, When the voltage across the motor terminal is varied, then the speed also gets varied accordingly. So this is the main principle of this project. A keyboard is connected to the Raspberry pi board to run the motor at different speeds by pressing the key.

According to the program, the PWM (pulse width modulation) is caused at the output, and it can be programmed by using PHP/wiring pi. Depending on the duty cycle, the average current and voltage change, so the speed of the DC motor will also change. A motor driver IC is interfaced to the board for receiving PWM signals and sending desired O/P to the DC motor.

Auto Intensity Control of Street lights by using Raspberry Pi

The main goal of this project is designed to control the auto intensity of street lights using Raspberry pi.

Hardware and Software Requirements

Transformer, Diodes, Capacitors, Resistors, LEDs, Raspberry pi board, TV or PC monitor, White LEDs, MOSFET, Crystal, PHP program or Wiring Pi

This project uses a bunch of LEDs as street lights which consume less power, and the lifetime of the LEDs is also more when compared to the HID lamps. A raspberry pi is used to control the intensity by developing pulse width modulation signals that drive a MOSFET to switch the LEDs to attain the desired operation.

The intensity of LEDs progressively varies from evening to the next day morning, particularly during the peak hours, with full light intensity, and then, the decreasing lights’ intensity slowly reduced. MOSFET switching by pulse width modulation technique is implemented in the raspberry pi program to have variable voltage across the LEDs

List of Raspberry Pi Based Projects

  • Programmable Sequential Switching by Using Raspberry pi
  • Raspberry Pi Based Solar Street Light
  • Synced Music and Christmas Lights
  • Raspberry pi Powered Wearable Computer
  • Home Automation Using Raspberry pi
  • Touch Screen Tablet
  • Raspberry pi Based Industrial Automation Using Zigbee Communication
  • Lego Raspberry pi Enclosure
  • Raspberry pi as an FM Transmitter
  • Autonomous Robot Arms Control Based on Raspberry pi with Bluetooth Control

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