🌟 Minimalistic E-Paper NTP-RTC Clock 🕒

🚨 IMPORTANT: Please read the [Notes & Warnings] section carefully before proceeding with this project. It contains crucial safety information about battery configuration, charging, and sensor placement.

🎯 System Specifications

🖥️ Core Components
🧠 Microcontroller	Xiao ESP32 C3 (Compatible with most ESP32 boards)
📺 Display	3.52" BiColor E-paper (360x240)
🔋 Power Source	LiFePO4 6000mAh 3.2V

⚡ Power Specifications
Operating Voltage	~3.2V
Sleep Duration	60 seconds
Battery Thresholds	📈 High: 3.4V 📉 Low: 2.9V

🔌 Communication
I2C Speed	400kHz (Fast Mode)
NTP Server	asia.pool.ntp.org
Time Offset	19800 (India, UTC+5:30)

🛠️ Hardware Components _{^{🔩 Parts List}}

Component	Specifications	Details
Xiao ESP32 C3	• MCU: ESP32-C3 RISC-V • Clock: 160MHz • RAM: 400KB SRAM • Flash: 4MB • WiFi: 2.4GHz • Bluetooth: BLE 5.0 • GPIO: 11 pins • Size: 21x17.5mm • Deep Sleep: ~43µA (when powered via BAT pins) • Note: Deep sleep current specified when battery connected to BAT pins	Ultra-compact IoT controller with low power consumption and built-in wireless capabilities. ESP32 C6 variant achieves ~14µA in deep sleep.
Waveshare 3.52" E-Paper	• Resolution: 360x240 • Colors: BiColor • Refresh: 1.5 secs	Display unit with low power consumption
BH1750	• I2C Address: 0x23 • Mode: ONE_TIME_HIGH_RES • Precision: 1-65535 lux	Ambient light sensor for night mode
DS3231	• Accuracy: ±2ppm • Temperature comp. • Battery backup	Real-time clock for timekeeping
IFR32650 LiFePO4	• Model: IFR32650 • Capacity: 6000mAh • Voltage: 3.2V nominal • Chemistry: LiFePO4 • Cycle Life: >2000 cycles • Size: 32x65mm • Max Discharge: 2C • Temperature Range: -20°C to 60°C • Self-discharge: 3% per month	High-capacity, safe chemistry battery with long cycle life and stable voltage output
TP5000	• Input: 5V USB • Output: 3.2V • Current: Up to 2A	Battery charging module
USB-C Breakout	• USB 2.0 Compatible • 5V Input • Data lines available	Power input and debugging interface

💫 Key Features ✨

⚡️ Power Efficient	🌙 Night Mode	🔄 Auto Update	📊 Battery Monitor
60s Deep Sleep	Light Sensor Based	Daily NTP Sync	Voltage Tracking

📈 System Architecture 🔄

graph TD
    A[Wake Up] --> B{Check Light}
    B -->|Dark| C[Sleep Mode]
    B -->|Light| D[Update Display]
    D --> E{Battery OK?}
    E -->|Yes| F[Update Time]
    F --> G[Update Display]
    G --> H[Deep Sleep]

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🚀 Quick Start 🎯

Prerequisites

Required Libraries:
  - Check header section inside .ino file
  - OEM Display Libraries (Included)

Installation Steps

1. Clone repository
2. Configure WiFi:

const char *ssid = "Your_SSID";
const char *password = "Your_PASSWORD";

3. Update pins in src/epdif.h
4. Upload code

🔋 Battery Performance ⚡

📊 Battery Life Analysis - Test #1 (With ESP32 C3)
Start Date	End Date	Runtime	Status
June 6, 2024	November 1, 2024	4 months 27 days	✅ Completed
Performance Metrics 🔋 Initial Voltage: 3.6V 📉 Final Voltage: ~2.84V 🌡️ Temperature Range: 17-38°C

📊 Battery Life Analysis - Test #2
Start Date	End Date	Runtime	Status
November 1, 2024	Coming Soon	In Progress	⏳ Running
Performance Metrics 🔋 Initial Voltage: 3.6V 📉 Final Voltage: TBD 🌡️ Temperature Range: Monitoring...

📊 Battery Life Analysis - Test #1 (With ESP32 C6)
Start Date	End Date	Runtime	Status
Coming Soon	Coming Soon	Coming Soon	Coming Soon
Performance Metrics 🔋 Initial Voltage: 3.6V 📉 Final Voltage: TBD 🌡️ Temperature Range: Coming Soon

📸 Gallery 🖼️

Front 1	Side 1	Back	Front 2
Inside 1	Inside 2	Inside 3	ESP32 C3 & C6

⚙️ Development 🔧

Build Requirements

• 💻 Arduino IDE 2.3.x or newer (tested)
• 📦 ESP32 Board Support Package
• 🔧 USB-C cable for programming
• 📚 Required libraries (see Prerequisites)

Debug Tips

• 🔍 Serial Monitor: 115200 baud
• 📊 Test points available for voltage monitoring (just lift the cover)

🌐 Connectivity 📡

• 📡 WiFi6 2.4GHz
• 🕒 NTP synchronization
• 🔄 Daily updates
• 💤 Auto sleep when inactive

🔬 Technical Details 📊

• 📈 ADC Resolution: 12-bit
• ⚡ I2C Speed: 400kHz
• 🔌 Power Modes:
  • 🟢 Active
  • 💤 Deep Sleep

⚠️ Important Notes & Warnings 🚨

🔄 DS3231 Battery Safety ⚡

Most DS3231 modules are sold with CR2032 or similar cells which are not rechargeable. If you are using a non-rechargeable cell then **REMOVE** either the resistor or the diode marked in the above image.

🔌 TP5000 Charging Configuration ⚡

There are some misinformation over internet regarding the charging mode of TP5000. If you are going to use LiFePO4 cell with TP5000 then **DO NOT** short the above marked area with caption F.

🔋 Battery Configuration Safety 🛡️

Power Management Considerations

• ⚡ Current Draw: This project's extremely low current consumption (well below rated cell capacity) makes the cell configuration safer
• 🛡️ Protection: Always use proper BMS protection for your cells
• 📝 BMS Setup: Due to limited 1S LiFePO4 BMS availability:
  • Using 4.2V BMS for 2.5V cutoff protection (Low Discharge Cutoff)
  • TP5000 connected directly to the cell for proper 3.6V charging
  • This is a temporary solution until better 1S LFP BMS options become available

USB Charging Safety

• ⚡ USB Connection Warning: Disconnect battery when connecting USB to ESP32C3
  • XIAO modules are designed for LiPo/Li-ion batteries (4.2V charging)
  • Not compatible with LFP battery charging (3.6V required)
  • Dedicated USB-C module recommended
  • Connect USB-C module output to TP5000 input
  • Detailed schematics will be provided later
  • Simple setup despite complex explanation

Voltage Compatibility

• ✅ Operating Range:
  • All components work perfectly with LFP's lower voltage
  • Tested operational down to 2.8V
  • No impact on battery life or performance
  • LFP cells maintain stable 3.2V for extended periods
  • 6+ months of testing
  • Components designed for wide voltage range operation

Enclosure Design

• 💨 Ventilation Requirements:
  • Proper air vents are crucial
  • Ensures accurate sensor readings
  • Prevents heat buildup

⚠️ Please consider these points carefully before replicating this setup. Battery safety is crucial!

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📜 License 📃

GNU General Public License v3.0

This project is licensed under the GNU GPL v3.0 - see below for details:

• ✅ Commercial use
• ✅ Modification
• ✅ Distribution
• ✅ Patent use
• ✅ Private use

Limitations

• ⚠️ Liability
• ⚠️ Warranty
• ℹ️ License and copyright notice required
• ℹ️ State changes
• ℹ️ Disclose source
• ℹ️ Same license

Read full license

🤝 Contributing 👥

We welcome contributions! Here's how you can help:

1. 🔍 Fork the repository
2. 🌿 Create your feature branch (git checkout -b feature/AmazingFeature)
3. 💾 Commit your changes (git commit -m 'Add some AmazingFeature')
4. 🚀 Push to the branch (git push origin feature/AmazingFeature)
5. 📝 Open a Pull Request

Pull Request Guidelines

• ✅ Clear description of changes
• ✅ Test your changes thoroughly
• ✅ Update documentation if needed
• ✅ Follow existing code style
• ✅ Add comments where necessary

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Made with ❤️ and ♻️ materials by 🌍 Earth-conscious developers