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Orange Unit: A Person-Centered Launch

4B: Meet the Microcomputer

Background Knowledge Probe

  • While looking through the list of toolkit items found in this textbook’s Introduction, what was the first thing that came to mind when you saw it included a Raspberry Pi? What inspired those thoughts regarding the Pi?
  • When you now compare and contrast a Raspberry Pi with your daily use computers, what are your current thoughts? Why have or haven’t they changed?
  • What design choices and design objectives might have inspired the Raspberry Pi’s layout function, look, and feel?

Technical Introduction

So far, each of our electronic circuits has been physically constructed using electronic components and electrical conductors, along with ground and 3.3 and 5 volt power sources. Many of our everyday technologies are built in just this way. Think of the essential lights, fans, and clocks around us. Even those with controllers to dim the lights, change the speed of a fan, or selectively tick-tock once a second are often made exclusively with electronic components and conductors and no more. But others also include programming code to add in features. Consider, for instance, a light connected to a remote timer allowing you to turn it on or off from your phone or laptop. In this chapter, we’re going to perform an upgrade to our Raspberry Pi. So far, it has performed as a helpful intermediate source for voltage and ground to our breadboard. Now, we’ll use it as a . Microcomputers are simply small computers that contain a microprocessor as its central processor. We’ll then install and run an application written using the Python , designed to work with the GPIO to turn LEDs on and off based on the current status of different momentary . As noted in this video below from the Raspberry Pi Foundation, “back in the 80s, kids had to learn how to code computers to use them. And as a result, these kids grew up with an inbuilt understanding of how computers worked.”[1] The Raspberry Pi microcomputer has been built from the ground up to “reignite this spark.” Not only is it being used specifically for information and communications technologies (ICT), it is serving a wide range of cross-curricular applications. And as illustrated, we’ll use it to push a button to turn on a light as the final exercise in this chapter!

As an aside, I was one of the fortunate kids who, back in the mid-70s, began learning how to code computers to use them to do things I valued. In this video below, I highlight some of this history, recounting my work with a teletype machine and acoustical modem to connect to a server, a punch card interface with that server, and programming with a Commodore 64 desktop computer.

The Components of the Raspberry Pi

The Raspberry Pi computer used throughout this book is built using a reduced instruction set computing (RISC) architecture known as ARM. This and similar architectures have slowly taken over the computer world, allowing us to do more for less. This is because RISC-based architectures require fewer than complex instruction set computing (CISC) architectures, such as those used in most desktop and laptop computers.

As a result, this has also opened up new computing opportunities, such as systems-on-chips (SoC) that bring together memory, input/output controllers, processors, radios, etc., into a single integrated circuit. The outcome is typically the lowering of costs, power consumption, heat dissipation, and potentially environmental impacts.

Below you can see Fritzing diagrams of both the Raspberry Pi 3 and Raspberry Pi 4 computers.

A schematic shows the electronic components of a Raspberry Pi Model 3.

A schematic shows the electronic components of the Raspberry Pi Model 4

Start by taking a few minutes to look over the hardware list for the Raspberry Pi 3 Model B, the earliest model of the third-generation Raspberry Pi.[2] This includes:

  • A Broadcom BCM2837 system-on-chip (the largest of the black, square integrated circuits on the printed circuit board). Built into this SoC is:
    • Quad-core 1.2 GHz 64-bit ARM cortex A53 CPU
    • Full HD 1080p, H.264 Video Encode/Decode, 400MHz VideoCore IV Graphical Co-Processor Unit
    • 1 GB SDRAM
    • 512 KB cache memory
  • One of the many smaller integrated circuits is a Broadcom BCM43438 chip that provides:
    • Wireless LAN
    • Bluetooth 4.1
  • Next to pin 1 of the GPIO, just above the “Made In” label, is the chip antenna for wireless LAN and Bluetooth signals.
  • Just off from the USB ports, you’ll find the SMSC LAN9514 chip, providing the controller for 10/100 Ethernet connectivity and four USB channels.
  • A variety of I/O connectors, sockets, and ports, including:
    • 4 USB 2 ports
    • Full size HDMI port
    • Micro SD port for loading an operating system and storing data
    • 10/100 Ethernet port
    • 4 pole stereo output and composite video port
    • 40-pin extended GPIO connector
    • Camera Serial Interface Type 2 (CSI) camera port, used to connect CSI-type cameras with the SoC chip
    • Display Serial Interface (DSI) port, used with a range of LCD and similar mobile display technologies
A reduced schematic of the Raspberry Pi 3 Model B highlighting the main circuits. Raspberry Pi, 2015.  CC BY-SA 4.0 International

From here, take a few more minutes at the Raspberry Pi Products website, using the “More Info >” link for one of each of the Raspberry Pi 3 Model B+, Model 3 A+, 4 Model B, 400, and Zero W products now available.

  • In what ways are these the same as the Raspberry Pi 3? In what ways are these unique from the Raspberry Pi 3?
  • In what contexts might one be of advantage over the others? In what contexts might one be less than ideal?

The Raspberry Pi OS

The Raspberry Pi Project has developed its own distribution of Debian’s GNU/Linux OS which it calls the Raspberry Pi OS. Debian strives to be a universal, completely free operating system, where free is not used as a monetary term but rather one of freedom. The Debian community has a written constitution that includes a social contract, diversity statement, and code of conduct, all of which are available from within the page introducing their philosophy. As a distribution based on Debian, the social philosophy of the community and technical changes to the software both eventually trickle over to the Raspberry Pi OS. Take some time to first review various social and technical aspects of Debian’s community and operating system from their homepage, then make your way over to the Raspberry Pi Foundation and the Raspberry Pi Project sites to learn more about the Raspberry Pi community and operating system.

  • In what ways might the vision, goals, and overarching philosophy of the Debian and Raspberry Pi communities have some parallels? What might be some ways that these could come into conflict?
  • In what ways does the Raspberry Pi OS take advantage of the technical aspects of the Debian OS? What are some things the Raspberry Pi add within its own distribution to especially serve its target audience(s)?

Exercise: Reviewing the Raspberry Pi Computer

Using these resources, create your own list of the physical components and operating system of the Raspberry Pi:

  • Input/output devices, such as types of USB ports, Thunderbolt ports, audio, camera, Ethernet, Bluetooth, card readers, etc.
  • Type and amount of random-access memory (RAM)
  • Storage devices
  • Central processing unit (CPU) and, if included, graphic processing unit (GPU)
  • Power source
  • Operating system (OS) type and version/subversion edition
  • Windowing system, desktop environment, and themes/skins. For many computers today, these are highly integrated, so you may only see this as a singular graphical user interface system.

If you can, boot up a working Raspberry Pi computer and have it running side-by-side with your own personal computer. Take a few moments to compare and contrast some of the installed applications on the Raspberry Pi (e.g., web browser, word processor, games) with similar ones on your laptop. As you do this, consider:

  1. In what ways is a given software on my laptop a better application based on specific design specifications?
  2. In what ways is a given software on my laptop a better application because of the hardware of my laptop?
  3. In what ways is a given software on my laptop a better application because of my familiarity with its design?
  4. In what ways might my answers to the above questions be shaped by the underlying vision, goals, and philosophy of the designers and distributors of a given software and of the underlying operating system on which it runs?

Repeat these three questions, this time considering in what ways the application might be better on the Raspberry Pi than on your laptop.

Wrap Up

The next task is to configure your own Raspberry Pi in preparation for the technical exercises to come. Depending on the tools at your disposal, there are numerous ways to accomplish this.

  1. Raspberry Pi learning resources and documentation are licensed under CC-BY-SA 4.0.
  2. Fritzing breadboard graphics are licensed under CC-BY-SA 3.0.


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A Person-Centered Guide to Demystifying Technology, 2nd Edition Copyright © 2023 by Martin Wolske Copyright © 2023. Copyright “Ideating and Iterating Code: Scratch Example” © 2020 Betty Bayer and Stephanie Shallcross. Copyright “Introducing the Unix Command Line” © 2020 Martin Wolske, Dinesh Rathi, Henry Grob, and Vandana Singh. Copyright “Security and Privacy” © 2020 Sara Rasmussen. Copyright “Storytelling in the Information Sciences” © 2023 Yingying Han and Martin Wolske. This book is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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