Fridge Calendar (E-Paper Google Calendar Display)

This project is an e-paper-based calendar display that integrates with Google Calendar to fetch and display daily events. It uses the ESP32-S3 microcontroller, the EPDiy library for e-paper control, and the Google Calendar API to retrieve event data. The device connects to WiFi for API calls and keeps track of local time for accurate scheduling and updates.

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Features

• 9.7-inch Black and White E-Paper Display: Displays a monthly calendar and upcoming events using the EPDiy library.
• WiFi Connectivity: Required for API calls to fetch Google Calendar events.
• Local Time Management: Synchronizes and maintains local time for accurate scheduling.
• Google Calendar Integration: Fetches events using Google Calendar API in JSON format.
• Automatic Daily Updates: Refreshes the display at 00:10 every day.
• Deep Sleep Mode: Saves power by putting the ESP32 into deep sleep between updates.
• Robust Retry Mechanism: Handles API call failures with a retry mechanism and enters indefinite deep sleep after repeated failures.

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Table of Contents

• Hardware Requirements
• Software Requirements
• Installation
• Usage
• Configuration
• System Workflow
• Troubleshooting
• License

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Hardware Requirements

• ESP32-S3 Based, Epdiy V7 board
  • Support for high-resolution displays with 16 data lines
  • Much faster updates thanks to the ESP32S3 SOC and the LCD peripheral
  • An on-board RTC, LiPo charging
• 9.7-inch black and white e-paper display(ED097TC2) compatible with the EPDiy library
• Power supply (battery or USB)

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Software Requirements

• ESP-IDF: ESP32 development framework (v5.3.1)
• EPDiy library: For e-paper control
• nlohmann/json: For JSON parsing
• Google Calendar API key and OAuth credentials
  • Learn about authentication and authorization
  • How to access Google APIs using OAuth 2.0 in Postman

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Installation

1. Clone the Repository

git clone https://github.com/0015/Fridge-Calendar.git
cd Fridge-Calendar

2. Create a Components Folder

Inside your project directory, create a components folder:

mkdir components

3. Add EPDiy Library

Clone the EPDiy library into the components folder:

cd components
git clone https://github.com/vroland/epdiy.git

4. Install JSON Parsing Library

Install the nlohmann-json library using the ESP-IDF dependency manager:

idf.py add-dependency "johboh/nlohmann-json^3.11.3"

5. Configure Project

Set your WiFi credentials, Google API credentials, and other configurations in app_config.h:

#define WIFI_SSID "your_wifi_ssid"
#define WIFI_PASS "your_wifi_password"
#define CLIENT_ID "your_client_id"
#define CLIENT_SECRET "your_client_secret"
#define ACCESS_TOKEN "your_access_token"
#define REFRESH_TOKEN "your_refresh_token"
#define CALENDAR_IDS "<multiple_calendar_ids>"
#define TIMEZONE "your_time_zone"

6. Build and Flash

idf.py build
idf.py flash

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Usage

• Upon powering up, the device connects to WiFi, synchronizes local time, and fetches Google Calendar events.
• Displays a monthly calendar and a list of upcoming events.
• Automatically updates at 00:30 every day or after a successful fetch of calendar events.
• If the API call fails twice in a row, the device enters indefinite deep sleep.

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Configuration

Google Calendar API Setup

1. Go to the Google Cloud Console.
2. Create a new project and enable the Google Calendar API.
3. Create OAuth credentials for your project.
4. Obtain the API key(Access Token), Refresh Token, client ID, and client secret.
5. Add the credentials to your app_config.h file.

WiFi Credentials

• Update the WiFi SSID and password in the app_config.h file.

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System Workflow

Initialization

1. Initialize Non-Volatile Storage (NVS) to store state information.
2. Display a splash screen and progress bar if this is the first run.
3. Connect to WiFi and synchronize local time.

Main Operation

1. Fetch events from Google Calendar using the REST API.
2. Parse JSON data into a usable format.
3. Display the calendar and events on the e-paper screen.

Retry and Sleep Logic

• On a failed API call:
  • Increment a retry counter stored in NVS.
  • Reboot and retry the operation.
• After two failed attempts:
  • Enter deep sleep indefinitely to save power.
• On success:
  • Reset the retry counter and schedule a wakeup for 00:30 the next day.

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Troubleshooting

Common Issues

1. WiFi Connection Fails:

   • Check your WiFi SSID and password in app_config.h.
   • Ensure the ESP32 is within range of the WiFi router.

2. Google API Fails:

   • Verify your Access Token, Refresh Token and OAuth credentials.
   • Check if the Google Calendar API is enabled in your Google Cloud Console.

3. NVS Errors:

   • Ensure NVS is initialized properly during startup.
   • Erase NVS if necessary using idf.py erase_flash.

4. E-paper Display Issues:

   • Verify the connection between the ESP32 and e-paper display.
   • Check if the EPDiy library is installed correctly.

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License

This project is licensed under the MIT License. See the LICENSE file for details.