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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 3 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 lower costs, power consumption, heat dissipation, and potentially lower environmental impacts.

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

Take a few minutes to look over the hardware of the Raspberry Pi 3 Model B that has come with your toolkit.[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 schematic of the Raspberry Pi Model B main circuits.

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.

Now, 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?

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 by Copyright © 2020 Martin Wolske. 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. is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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