Activity 4.2.5 — Digital Christmas Display Design Brief¶

Learning Objectives¶

By the end of this lesson, students will be able to:

Create a design brief for a digital electronics project
Plan and document a project that integrates sensors, logic, and microcontrollers
Follow a design process to build a working prototype
Present and document their completed project

Vocabulary¶

Vocabulary (click to expand)

Term	Definition
Design Brief	A document that defines project goals, requirements, and constraints
Prototype	A working model of the final product
Block Diagram	A diagram showing system components and their connections
Iteration	The process of repeatedly improving a design
Documentation	Written materials that explain how the system works

Part 1: Project Overview¶

This is your chance to design and build a complete digital system that demonstrates everything you've learned in this course: combinational logic, sequential logic, sensors, and microcontrollers.

Project Theme: Digital Christmas Display¶

Create a digital display that combines the magic of the holiday season with your electronics skills. Your project should be something you can demonstrate at the Engineering Showcase.

What You'll Build¶

This is a design brief — a document that tells you what to build. You will need to make decisions about: - Which project to build - What components to use - How to implement the logic - How to present your work

Part 2: Project Options¶

Choose ONE of these project ideas (or propose your own with approval):

Option A: LED Light Show¶

Multiple LEDs arranged in patterns (tree shape, snowflake, star)
Arduino controls sequencing and patterns
Switch between patterns automatically or with button input
Required: At least 12 LEDs, 2+ patterns, pushbutton selector

Option B: Countdown Timer¶

Days/hours/minutes until Christmas displayed on 7-segment or LCD
Real-time clock (RTC module or calculated)
Alarm when countdown reaches zero
Required: Display shows at least minutes, countdown works correctly

Option C: Interactive Ornament Game¶

Touch sensor or button input from users
Memory game: watch the pattern, repeat it
Score tracking with LEDs or display
Required: At least 4 input buttons, audio feedback, scoring

Option D: Musical Doorbell¶

Visitor detection (IR sensor or button)
Play holiday melodies using buzzer or speaker
Visual display shows who's at the door
Required: Plays at least 3 different melodies, visual indicator

Option E: Smart Wrapping Station¶

Sensor detects when gift is placed on table
Timer measures wrapping time
Score display for speed
Required: Sensor input, timing, display output

Key insight: Choose a project that matches your skill level and interests. You can always expand a simpler project with more features.

Part 3: Design Requirements¶

Every project MUST meet these requirements:

Must Include:¶

At least one sensor input (IR sensor, button, potentiometer, photoresistor, etc.)
At least one output (LED, motor, display, buzzer/speaker)
State machine behavior (system has distinct states that respond to inputs)
Both digital logic AND Arduino code (use at least one logic IC and one Arduino feature)

Technical Requirements:¶

Arduino controls main logic flow
At least 2 inputs and 2 outputs
Code must use state machine or switch/case structure
Must include comments explaining the code
Must function reliably

Part 4: Design Process¶

Follow these steps to complete your project:

Step 1: Choose Project¶

Select one of the options (or propose your own). Write a 2-3 sentence description of what you will build.

Step 2: Write Requirements¶

Create a requirements list: - What inputs will you use? - What outputs will you use? - What will the system do? - What states will it have?

Step 3: Draw Block Diagram¶

Show how components connect: - Sensors → Arduino → Outputs - Include power connections

Example block diagram:

[Button] ----> [Arduino] ----> [LEDs]
   |              |
   |              v
[Sensor] ----> [Logic IC] ----> [Display]

Step 4: Design Circuit¶

List all components
Show pin connections
Include pull-up/pull-down resistors if needed

Step 5: Write Code¶

Plan your state machine first
Write code in sections (setup, inputs, state logic, outputs)
Add comments throughout

Step 6: Build Prototype¶

Connect all components
Test each part separately
Fix problems as they appear

Step 7: Test and Refine¶

Run through all possible inputs
Check all outputs work
Add features or fix bugs

Step 8: Document and Present¶

Create poster or presentation
Prepare demonstration
Write explanation of how it works

Part 5: Assessment Rubric¶

Your project will be graded on these categories:

Functionality (40%)¶

System works as designed
All inputs respond correctly
All outputs activate properly
State transitions work reliably

Code Quality (20%)¶

Code is well-commented
Uses proper structure (setup/loop/functions)
State machine clearly implemented
Variables have meaningful names

Documentation (20%)¶

Complete design brief
Clear circuit diagram
Block diagram present
Explanation of how it works

Presentation (20%)¶

Demonstrates project to class
Explains design decisions
Shows code and circuit
Answers questions about the project

Part 6: Project Timeline¶

Milestone 1: Project Selection (Day 1-2)¶

[ ] Choose project option
[ ] Write initial description
[ ] Submit for approval

Milestone 2: Design Complete (Day 3-4)¶

[ ] Requirements list
[ ] Block diagram
[ ] Component list
[ ] Circuit design

Milestone 3: Code Complete (Day 5-6)¶

[ ] Write Arduino code
[ ] Test in simulation (Tinkercad)
[ ] Debug logic errors

Milestone 4: Build Complete (Day 7-8)¶

[ ] Build circuit
[ ] Upload code
[ ] Test functionality

Milestone 5: Final (Day 9-10)¶

[ ] Polish and debug
[ ] Documentation complete
[ ] Present to class

Part 7: Example Project Plan¶

Here's an example of how to plan your LED Light Show:

Project: Christmas Tree Light Show¶

Description: A string of 20 LEDs arranged in a tree shape that cycles through 5 different light patterns. A pushbutton selects patterns, and a potentiometer controls speed.

Requirements: - 20 LEDs (red, green, yellow) - 1 pushbutton (pattern select) - 1 potentiometer (speed control) - Arduino Uno - Shift register (74HC595) for LED control - Buzzer for optional music

Block Diagram:

[Potentiometer] --> [Arduino]
                         |
[Pushbutton] -----> [Arduino]
                         |
                    [74HC595] --> [LEDs]
                         |
[Buzzer] <-------- [Arduino]

State Machine: - STATE_1: All blink together - STATE_2: Alternating blink - STATE_3: Running lights - STATE_4: Random twinkle - STATE_5: Color chase

Components: - Arduino Uno: $15 - 74HC595: $0.50 - LEDs (20): $2.00 - Resistors (20): $1.00 - Pushbutton: $0.50 - Potentiometer: $1.00 - Buzzer: $1.00 - Wire, breadboard: $2.00 - Total: ~$23

Key insight: Plan your budget and gather all components before starting to build. Know what resources are available in the lab.

Planning Worksheet¶

Use this worksheet to plan your project:

Project Title: _________

Option (A/B/C/D/E): ______

Description (2-3 sentences):

Inputs (what triggers the system?): 1. __ 2. __

Outputs (what does the system do?): 1. __ 2. __

States (what modes does the system have?): 1. __ 2. __ 3. ___

Components Needed: - Arduino: _ - Sensors/Inputs: _ - Outputs: _ - Other ICs: _

Timeline Milestones: - Design due: _ - Code due: _ - Build due: _ - Present: _

Summary¶

This project combines everything you've learned: logic design, sequential circuits, sensors, and microcontrollers
Follow the design process: choose → plan → build → test → document
Meet all requirements: sensor input, output, state machine, both logic and Arduino
Document your work thoroughly for presentation

Key Reminders¶

Start with a clear design brief before building
Test components individually before integrating
Use comments in code for yourself and others
Keep backup copies of working code
Leave time for debugging and refinement

Custom activity — adapted from PLTW Digital Electronics