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https://github.com/desifish/epaper-display-ntp-clock

E-Paper Display based efficient NTP Clock
https://github.com/desifish/epaper-display-ntp-clock

32650 arduino arduino-ide bh1750 bms clock ds3231 e-paper e-paperdisplay esp32 lifepo4 lifepo4-battery ntp smart-clock temperature-sensor tp5000 usbc waveshare-epaper xiao-esp32-c3 xiao-esp32c6

Last synced: 3 months ago
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E-Paper Display based efficient NTP Clock

Awesome Lists containing this project

README 

        


  
🌟 Minimalistic E-Paper NTP-RTC Clock 🕒


  


    

    

    

    

  


  


    Status

    License

    GitHub Issues

    Release

  





> 🚨 **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 C6 (Compatible with most ESP32 boards)

  

  

    📺 Display

    Waveshare 3.52" BiColor (Black and White) 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 C6

  

    • MCU: ESP32-C6 RISC-V


    • Clock: 160MHz


    • RAM: 512KB SRAM


    • Flash: 4MB


    • WiFi: 2.4GHz (WiFi6)


    • Bluetooth: BLE 5.0


    • Size: 21x17.8mm


    • Deep Sleep: ~16µA (when powered via BAT pins)


  

  Note: Deep sleep current specified when battery connected to BAT pins



  
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

      Periodic NTP Sync

      Voltage Tracking

    

  




## 📈 System Architecture 🔄

```mermaid

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]

```



## 🚀 Quick Start 🎯



Prerequisites



```yaml

Required Libraries:

  - Check header section inside .ino file

  - OEM Display Libraries (Included in src)

```



Installation Steps



1. Clone repository

2. Configure WiFi:

```cpp

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 (With ESP32 C3)



  

    Start Date

    End Date

    Runtime

    Status

  

  

    November 1, 2024

    April 2, 2025

    5 months 2 days

    ✅ Completed

  

  

    

      Performance Metrics


      🔋 Initial Voltage: 3.6V


      📉 Final Voltage: 2.79V


      🌡️ Temperature Range: 15-36°C

    

  







  

    📊 Battery Life Analysis - Test #1 (With ESP32 C6)

  

  

    Start Date

    End Date

    Runtime

    Status

  

  

    April 6, 2025

    TBD

    TBD

    TBD

  

  

    

      Performance Metrics


      🔋 Initial Voltage: 3.54V


      📉 Final Voltage: TBD


      🌡️ Temperature Range: TBD

    

  






## 📸 Gallery 🖼️




  

    

      


      Front 1

    

    

      


      Side 1

    

    

      


      Back

    

    

      


      Front 2

    

  

  

    

      


      Inside 1

    

    

      


      Inside 2

    

    

      


      New UI

    

    

      


      ESP32 C3 & C6

    

  

      

    

      


      New Sleep UI

    

    

      


      Inside 4

    

    

      


      Inside 5

    

     

      


      Inside 6

    

  






## ⚙️ 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

- 💤 Auto sleep when dark



### 🌙 Deep Sleep Implementation with DS3231 RTC

> ⚠️ **Important Note**: No single source provided a complete working solution for deep sleep with DS3231 RTC. This implementation combines key elements from multiple references to create a reliable solution.



The project implements an efficient deep sleep mode using the DS3231 RTC's external alarm feature. This approach significantly reduces power consumption while maintaining accurate timekeeping.



#### How it Works

1. The DS3231 RTC SQW pin is connected to GPIO7 (MTDO) (RTC GPIO)

2. The RTC alarm triggers a signal on the SQW pin

3. ESP32-C6 wakes up from deep sleep on the falling edge



#### Key Implementation Points

- Wake-up Source: `esp_sleep_enable_ext0_wakeup(GPIO_NUM_7, 0)`

- Wake Up Interval: 60 seconds (configurable)

- Current Consumption: ~16µA in deep sleep (for XIAO ESP32C6 only)



#### References

These sources were combined to create a working implementation:

1. [ESP32 Wake-Up Using DS3231 RTC](https://randomnerdtutorials.com/esp32-wake-up-deep-sleep-external-alarms-ds3231/) - Basic RTC alarm setup

2. [XIAO ESP32C6 Deep Sleep Guide](https://wiki.seeedstudio.com/xiao_esp32c6_getting_started/#demo1-deep-sleep-with-external-wake-up) - ESP32-C6 specific wake-up configuration

3. [ESP32 External Wake-Up Implementation](https://randomnerdtutorials.com/esp32-external-wake-up-deep-sleep/) - External wake-up pin handling



## ⚠️ 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 ESP32C6 (Use a switch to cutt-off battery)

  - XIAO modules are designed for LiPo/Li-ion batteries (4.2V charging)

  - Not compatible with LFP battery charging (3.6V required)

  - 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!**

---



## 📜 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](/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

---



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