Athenian 2021–22 Winter After-School Computer Science Class

Fun with Electronics and Coding, with Dave Briccetti

Short link to this page: bit.ly/db-tas-6
Go to the latest lesson.

In this class, for beginning and experienced programmers and “digital makers”, you’ll create several fun projects combining coding with wiring up buttons, sensors and motors, while strengthening your programming skills, and being exposed to the big ideas of computer science.

Hardware

We’ll work with several tiny computers and microcontrollers.

The Raspberry Pi is a full-featured, but small, computer.

The Circuit Playground Express is less powerful than the Raspberry Pi, but includes many sensors and lights, and consumes less power.

Circuit Playground Express photo

The Arduino is a very popular microcontroller, with a large community creating software for it.

Software

Python is one of the most popular programming languages, and it’s suitable for beginning programmers as well as professionals.
JavaScript/TypeScript is another of the most popular programming languages.
C++ is used for programming Arduinos.
MakeCode for Circuit Playground Express makes it easy to program the CPX using blocks.
Tinkercad Circuits lets you try out your electronics circuits in a simulator before assembling them with real components.

Projects

The best projects might be the ones students come up with themselves, but here are some ideas:

Multiplayer Reaction/Memory Lights Game

Inspired by Simon game

Code walkthrough video

Features:

Raspberry Pi tiny computer
Python and TypeScript (a better JavaScript) programming languages
making a web application (webapp) with the Flask framework
Hypertext Markup Language (HTML) and Cascading Style Sheets (CSS)
electronics fundamentals
connecting components on a breadboard
reading button presses
lighting multicolor LEDs

Smart Thermostat

Make a smart thermostat to control your home temperature.

Dave’s YouTube Electronics Playlist should provide more ideas.

The Teacher

Dave Briccetti is a highly skilled programmer and experienced computer science teacher. Watch him teach on his YouTube channel.

Have a look at Dave’s Fall, 2021, class, Programming an Adventure Game… to get a feel for what Dave’s classes are like.

Bring to Class

Bring your own laptop computer running macOS, Windows, or Linux, or use one provided by the school. The school will provide hardware to use during the class, and you’re welcome to bring your own hardware.

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Circuit Playground Express (CPX)

Adafruit’s CPX Page introduces the CPX.

We’ll use MakeCode for CPX. Microsoft describes MakeCode as “a free online learn-to-code platform where anyone can build games, code devices, and mod Minecraft!”

Explore Tutorials and Play

Send a Program to the CPX

Hot Wheels Track Challenge

How could you use a CPX to determine when a car reaches the finish line?

2022-01-27

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¹No pigeons are harmed

Circuit Playground Express (CPX)

Different Ways to Program

MakeCode
- Blocks
- JavaScript
CircuitPython

Servo Motors

Our hardware projects can sense the environment (using light, sound, pressure, acceleration, etc.) and can effect change in the environment (using motors, light, sound, etc.). Today we’ll connect servo motors to our CPXes. Here are some of Dave’s projects using CPX or Arduino and servos:

Connecting the Servo

Make connections as shown here:

Picture showing connecting a CPX to a Servo motor

Make Something with the CPX and the Servo

Here’s what Dave made (MakeCode project):

What will you make?

2022-02-01

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Maker and BJC Curriculum Developer Deanna Gelosi

Review

So far we’ve programmed the Circuit Playground Express (CPX) to do various things, including controlling a servo motor.

Thanks to BJC

The micro:bits, breakout boards, and batteries are provided by The Beauty and Joy of Computing.

micro:bit

Today we’ll start using the micro:bit. They have a lot in common with the CPX, including:

LEDs
sound
sensors (light, heat, acceleration, etc.)
motor control ability

Breakout Boards

A breakout board makes it easier to connect a device such as the micro:bit to other components. It is easier to connect a servo motor to the micro:bit because the breakout board has headers, pins that connect directly to the servo’s female connectors.

Trying Out the micro:bit

Use the USB cable in the kit to connect the micro:bit to your computer. Be gentle. The micro:bit should power up and then engage you for a few minutes in an interesting way that shows some of its features.

Connect to the Breakout Board

Gently insert the micro:bit into the connector on the breakout board.

Connect the Servo

Servo connection

Make a Program

As before with the CPX, we’ll use MakeCode, but a different version of it for micro:bit.

Here’s Dave’s example.

Download Directly to the micro:bit (No Drag and Drop Needed)

This requires Chrome or Edge. Click on the gear icon and choose Connect device. Once connected, push Download and that’s all that’s needed.

Battery Pack

You can disconnect the micro:bit from the computer once you have it programmed, and instead power it from a battery pack. Connect the battery pack as shown here (red to +, black to -). When disconnecting, don’t pull the wires. Pull on the plastic piece instead.

Power connection

Play Time

Play with the servo, the LEDs, sound, the accelerometer, whatever you like! Make something.

Radio Communication

This is one of Dave’s favorite features. These devices can communicate with each other using radio transmissions. If we have time we’ll play with it.

Observations

Students connected the components with very little trouble. They spent lots of time trying out the LED, sound, accelerometer and other functions. One student made a game using buttons to move a pixel around on the display. Another expressed interest in the radio, and it spread from there with at least half the class trying the features.

Two pairs of students took the micro:bits outside in order to estimate the range of the radio transmissions. One group arrived at 57 meters. I’ve since learned you can control the signal strength with a MakeCode block, and the default value is a bit lower than the maximum.

I didn’t see anyone use a servo motor.

2022-02-03

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Athenian FIRST Robotics Team Prepares for Competition.

Tour of Athenian FIRST Robotics Development Efforts

Correction

MakeCode for CPX (running on Chrome or Edge) supports downloading directly to the CPX, as does MakeCode for micro:bit.

Hot Wheels Track Progress

MakeCode Programs

The Car-Detection Circuit

Challenges

Can you modify the Coordinator such that it times the car and displays the elapsed time when the car reaches the finish line?

More with micro:bit

Communicating by Radio

Ideas:

make a “repeater chain” to extend the range of transmissions. How far can it reach?
Using several micro:bits, have a “composer” tell the other micro:bits what notes to play. Can you play chords and melodies?

Using Servo Motors

Ideas:

think synchronized swimming

Observations

We had a tour of Athenian’s FIRST Robotics team’s work areas. Several students asked interesting questions, resulting in lots of interaction between the team members and the class.

In the remaining 25 minutes or so, students accomplished a lot:

Respond to shake
(Two students) multiple channel radio broadcast
Hello in different languages
Servo motor
Remote-controlled game with buttons
Rock, paper, scissors
Music, rock, paper, scissors
Scrolling text
Rock, paper, scissors

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Improved Starting Gate

Mike Meneghetti designed and built a better starting gate using cardboard, hot glue, a craft stick screwed into the servo’s horn, and a bit of adhesive putty.

Mike’s starting gate

Different Finish Line

Mike built this as well. It works where the optical solution doesn’t—when the car is moving really fast. Mike’s finish line

Slow Motion Car Start and Finish

Light Meter Project

We’ll make light meters using light level and a servo motor.

Mapping One Range to Another

light level yields a number from 0 to 255. We want to use that range of numbers to set the angle of a servo motor (0–180). What sort of divisions and/or multiplications must we do to change light levels to angles?

Other Activities

What are you interested in trying? Combining radio and servo functions?

Observations

Most students did the light meter project, but for a few, we couldn’t get the servos to move. Dave checked the wiring, the code, and that the micro:bits were paired and the code was downloaded.

One student, using a tutorial, connected a banana and an orange to the micro:bit and played tones by touching it. Another made a program to monitor multiple radio channels. Two students continued work on their drawing program. One used the if block to show different icons depending on the light level.

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Laser Cutting

Using InkScape to define what is to be cut: Project in Inkscape

The finished cut wood:

Shall we assemble it?

Programming the micro:bit in Python

Follow Dave as we program in MakeCode with Python.

Free Play Time

Tutorials

Have you tried out the tutorials? Some are made specifically for the micro:bit version 2, which we have.

Crafting

We have cardboard, craft sticks, and glue guns if anybody wants to do some of that type of thing.

Observations

The Programming in Python activity ran into a bit of a problem when a student wanted to access the compass heading, and Dave, eager to follow students’ interests, tried it out with the following code:

heading = input.compass_heading()
basic.show_number(heading)

This code worked fine in the simulators, but once on the micro:bit, it caused unexpected messages to appear, which Dave later discovered is a calibration sequence for the compass: You have to tilt the micro:bit to “fill the screen”.

Three students assembled a launching gate from the laser-cut pieces:

Assembled gate

Others did tutorials and explored their own ideas.

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New Design for Hot Wheels Gate

Gate parts in Inkscape

Group Activity: Programming a Time-Delayed Gate in Python

Here we’ll have a Hot Wheels track with three gates. The first will hold the car until the gate is opened. The others will open after a configurable delay. What’s the point of the other gates? We’re pretending that they only allow “friendly” cars to pass. They should open just in time for the car to pass.

Gates along Hot Wheels Track

The program has two operating modes: normal mode and setup mode. To switch between the modes, press A and B together. Once in setup mode you can change the delay units value using the A and B buttons. The units are 1/4 second. This table shows the delay in seconds for each of the ten delay units values.

Delay Units	Seconds
0	0
1	0.25
2	0.5
3	0.75
4	1
5	1.25
6	1.5
7	1.75
8	2
9	2.25

Setup

Create a new project
- Expand Code options and choose Python only
Install the Servo extension
Use radio group 1
Create variables
- setup_mode = False
  - Pressing A and B together toggle setup mode
- delay_units = 0
  - How many “units” to delay after receiving the “go” command before raising the gate. It starts at zero but can be changed within the range 0–9 using the A and B buttons when in setup mode
- unit_value = 250
  - The number of milliseconds per delay unit
Show delay_units on the display

Event handlers

A+B pressed
- toggle the setup_mode variable
  - to toggle a boolean named b: b = not b
A pressed
- if in setup mode and delay_units > 0
  - decrement delay_units
  - Show delay_units on the display
B pressed
- if in setup mode and delay_units < 9
  - increment delay_units
  - Show delay_units on the display
Radio received string
- if the string is “go”
  - pause for unit_value × delay_units milliseconds
  - play a brief musical tone
  - set servo angle to 90°
  - pause for 1/2 second
  - set servo angle to 180°

Here is one solution:

radio.set_group(1)
setup_mode = False
delay_units = 0
unit_value = 250
basic.show_number(delay_units)

def on_button_pressed_ab():
    global setup_mode
    setup_mode = not setup_mode
input.on_button_pressed(Button.AB, on_button_pressed_ab)

def on_button_pressed_a():
    global delay_units
    if setup_mode and delay_units > 0:
        delay_units -= 1
        basic.show_number(delay_units)
input.on_button_pressed(Button.A, on_button_pressed_a)

def on_button_pressed_b():
    global delay_units
    if setup_mode and delay_units < 9:
        delay_units += 1
        basic.show_number(delay_units)
input.on_button_pressed(Button.B, on_button_pressed_b)

def on_received_string(receivedString):
    if receivedString == 'go':
        basic.pause(unit_value * delay_units)
        music.play_tone(Note.C, music.beat())
        servos.P1.set_angle(90)
        basic.pause(500)
        servos.P1.set_angle(180)
radio.on_received_string(on_received_string)

Code in Blocks

Curious what this project would look like if we had made it with blocks?

Project with blocks

Observations

This was challenging. Nevertheless, several students got the code working right by the end. Others copied Dave’s solution above. It would have been helpful to show the working program at the beginning to help the students understand more clearly what they are building. The concept of a “setup mode” was confusing to some, and having different modes made the program more complex, without adding any immediate benefit.

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Finishing The Gate Project

Here’s the latest code, with some new features, and with the setup mode removed.

Download the program to the micro:bit. Run it, and use the A and B buttons to choose a delay units value. Let’s use all values from 0 to 9. Dave will send the new play command and your micro:bits will play a tone. Then he’ll send the go command and your micro:bit will respond after the delay you’ve set up.

Free Play Time

Customize the gate program (with sound or other features), or make something new. Try a new tutorial?

2022-02-24

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Arduino

Here’s a project Dave has been working on. It uses an Arduino. Arduino lacks some friendly features that Circuit Playground Express and micro:bit have, but it provides other features, such as supporting both 5 volts and 3.3 volts. Dave used it for this project because the ultrasonic range finder requires 5 volts. Unlike the other microcontrollers we’ve used, Arduino is usually programmed in the C++ language (which is very fast compared to Python, but much more difficult).