iot-button-system

This tutorial walks you through building a small end-to-end IoT system: a physical button connected to an Arduino board that communicates with a cloud backend hosted on Amazon Web Services.

By the end, you will have a working IoT pipeline from a physical button press to cloud-side logic and back.

sequenceDiagram
    box Edge Device
        participant PB as Push Button
        participant L as LED
        participant A as Arduino
    end

    box AWS Cloud
        participant I as AWS IoT Core
        participant R as Lambda: run_backend
        participant T as Lambda: get_time
    end

    PB->>A: Button pressed
    A->>L: LED off
    
    A->>I: MQTT Publish\nTopic: arduino/outgoing\nPayload: { timezone_offset }
    
    I->>R: IoT Rule triggers run_backend\n(event payload forwarded)
    
    R->>T: Call get_time(timezone_offset)
    T-->>R: Return { minutes }
    
    R->>I: MQTT Publish\nTopic: arduino/inbound\nPayload: { minutes }
    
    I->>A: Deliver MQTT message\nTopic: arduino/inbound\n{ minutes }
    
    A->>L: Blink LED N times\n(N = current minute)

    A->>L: LED on

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Main Objectives - Build an End-to-End IoT Cloud System

• Build a complete system using an Arduino, MQTT, AWS IoT Core, and AWS Lambda.
• Publish and subscribe to MQTT topics (arduino/outgoing, arduino/inbound).
• Trigger a Lambda function from an IoT rule and process cloud-side logic.
• Send data back to the device and translate it into a physical action (LED blinking).
• Understand the full edge -> cloud -> edge communication loop.

Secondary Objectives - Professional Engineering Practices

• Version the project using Git and GitHub.
• Develop embedded firmware using PlatformIO and Visual Studio Code instead of the Arduino IDE.
• Apply good security practices (secrets files, IAM users and roles, secure MQTT policies).
• Structure a multi-component system clearly.

Structure of the tutorial

Warning

IoT systems mix hardware, firmware, networking, and cloud infrastructure. When something does not work, the issue could be anywhere. If you connect everything at once, debugging quickly becomes painful.

Thus, this tutorial follows a strict order:

1. Make the hardware work.
2. Make the device talk to your computer.
3. Make it connect to the Internet.
4. Make it talk to AWS.
5. Add backend logic in the cloud.

Take the tasks in order. Do not move on until the current step behaves exactly as expected. That discipline is what makes larger systems manageable.

🔧Task 1 - Building and Testing the edge device

sequenceDiagram
    box Edge Device
        participant PB as Push Button
        participant LED as LED
        participant MCU as Arduino (Firmware)
        
    end
    participant SM as Serial Monitor


    PB->>MCU: Button pressed
    MCU->>LED: Turn OFF
    MCU->>SM: Print "Waiting for reset..."
   
    SM->>MCU: Send integer (e.g. 3)

    MCU->>LED: Blink N times\n(N = received integer)

    MCU->>LED: Turn ON
    MCU->>SM: Print "Reset received"

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Button, LED, firmware logic, and a simple serial handshake. No Internet, no cloud.

👉 Click here to read the instructions for task 1.

📶Task 2 - Connecting the edge device to the internet

sequenceDiagram
    box Edge Device
        participant PB as Push Button
        participant LED as LED
        participant MCU as Arduino (Firmware)
    end
    box Internet
        participant WIFI as WiFi Router
        participant EXT as httpbin.org
    end



    MCU->>WIFI: WiFi.begin(SSID, PASSWORD)
    WIFI-->>MCU: Connected (WL_CONNECTED)

    PB->>MCU: Button pressed
    MCU->>LED: Turn OFF

    MCU->>EXT: client.connect("httpbin.org", 80)

    alt Connection successful
        EXT-->>MCU: Connection established
        MCU->>LED: Blink 3 times
        MCU->>EXT: client.stop()
    else Connection failed
        MCU->>LED: Blink 9 times
    end

    MCU->>LED: Turn ON
   

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The device connects to WiFi and performs a basic external request. We confirm networking works before touching AWS.

👉 Click here to read the instructions for task 2.

☁️Task 3 - Connecting the edge device to AWS IOT Core

sequenceDiagram
    box Edge Device
        participant PB as Push Button
        participant LED as LED
        participant MCU as Arduino (Firmware)
        
    end
    participant WIFI as WiFi Router
    box AWS Cloud
        participant IOT as AWS IoT Core (MQTT Broker)
    end

  

    MCU->>WIFI: WiFi.begin(SSID, PASSWORD)
    WIFI-->>MCU: Connected


    PB->>MCU: Button pressed
    MCU->>LED: Turn OFF
    MCU->>IOT: Attempt MQTT TLS connection\nport 8883

    alt Connection successful
        MCU->>IOT: MQTT CONNECT (TLS + X.509)
        IOT-->>MCU: CONNACK
        MCU->>IOT: Publish "hello..."\nTopic: arduino/outgoing
        MCU->>LED: Blink 3 times
    else Connection failed
        MCU->>LED: Blink 9 times
    end

    MCU->>LED: Turn ON

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Secure MQTT communication with the cloud. We verify the device can connect and exchange messages.

👉 Click here to read the instructions for task 3.

🧠Task 4 - Create a system backend using AWS Lambda triggered by AWS IoT Core

sequenceDiagram
    box Edge Device
        participant PB as Push Button
        participant L as LED
        participant A as Arduino
    end

    box AWS Cloud
        participant I as AWS IoT Core
        participant R as Lambda: run_backend
        participant T as Lambda: get_time
    end

    PB->>A: Button pressed
    A->>L: LED off
    
    A->>I: MQTT Publish\nTopic: arduino/outgoing\nPayload: { timezone_offset }
    
    I->>R: IoT Rule triggers run_backend\n(event payload forwarded)
    
    R->>T: Call get_time(timezone_offset)
    T-->>R: Return { minutes }
    
    R->>I: MQTT Publish\nTopic: arduino/inbound\nPayload: { minutes }
    
    I->>A: Deliver MQTT message\nTopic: arduino/inbound\n{ minutes }
    
    A->>L: Blink LED N times\n(N = current minute)

    A->>L: LED on

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AWS IoT rules and Lambda functions complete the end-to-end system.

👉 Click here to read the instructions for task 4.

Repository structure

iot-button-system/
|---docs/ # Contains the step by step instructions for this tutorial
|---firmware/ # Contains Arduino code for the MKR WIFI 10101 board
|---infra/ # Contains AWS IOT config files
|---lambdas/ # Contains AWS Lambda function code written in python

Hardware Requirements

• Arduino MKR WIFI 10101.
• LED kit.
• Push button kit.