This project displays a daily C++ quiz question from cppquiz.org on an e-paper display powered by an ESP32 microcontroller. Questions are fetched via Google Apps Script connected to a Google Sheets backend, then rendered with clean formatting on a 7.5" E-Ink screen.

🚀 Features

• Displays C++ quiz question from a Google Sheet
• Works offline by caching the last successful question
• Uses deep sleep to save power (wakes up every hour)
• Shows Wi-Fi status for shown question (connected/disconnected) with an icon
• Fully customizable via Google Sheets + Apps Script backend

📦 Hardware

• ESP32
• Waveshare ESP32 Epaper Driver Board
• Waveshare 7.5" E-Paper Display

🧠 How It Works

• ESP32 boots and connects to Wi-Fi.
• It sends an HTTP request to a Google Apps Script endpoint.
• The Apps Script reads a unshown question from Google Sheets and returns it as plain text.
• ESP32 displays the question on the e-paper screen.
• If Wi-Fi fails, it loads the last cached question.
• Device goes into deep sleep and repeats after one hour.

🎉 To Build Yourself

• Software

  • Upload an Excel file (questions.xlsx) to Google Drive
  • Open it with Google Sheets
  • In your Google Sheet:
    • Click Extensions > Apps Script
    • Paste the code.gs (code.gs)
  • Deploy the script as a Web App
  • Set access to "Anyone with the link"
  • Update code.gs (code.gs):

    var sheet_id = "YOUR_GOOGLE_SHEET_ID"; //Excel

• Hardware

  Update config.h (config.h)on ESP32 firmware:

  const std::string WIFI_SSID         = "YOUR_WIFI_SSID";
  const std::string WIFI_PWD          = "YOUR_WIFI_PWD"
  const std::string GS_DEPLOYMENT_ID  = "YOUR_GS_DEPLOYMENT_ID"

📄 Why Use an Excel File?

The questions displayed on this device are sourced from cppquiz.org, which provides a comprehensive collection of C++ questions. However, the site does not offer an API to fetch individual questions by ID.

Instead, all questions are made available as a bulk JSON file at:

https://static.cppquiz.org/published.json

Due to the size of this dataset and the need for easier navigation, filtering, and tracking of displayed questions, I chose to manage the content through a Google Sheets with Google App Script.