https://github.com/nithinmathewjoji/schrodinger-clock-pcb-watch-
An open-source ESP32-S3-based smartwatch with RTC, I2C display, buzzer, LEDs, and battery monitoring. Designed using KiCad, it features a compact PCB layout, Li-Po battery support, and USB charging
https://github.com/nithinmathewjoji/schrodinger-clock-pcb-watch-
circuit esp32 funproject pcb pcb-design pcbwatch rtc-module schrodingers-cat tp4056 watch wearable-devices
Last synced: 11 months ago
JSON representation
An open-source ESP32-S3-based smartwatch with RTC, I2C display, buzzer, LEDs, and battery monitoring. Designed using KiCad, it features a compact PCB layout, Li-Po battery support, and USB charging
- Host: GitHub
- URL: https://github.com/nithinmathewjoji/schrodinger-clock-pcb-watch-
- Owner: nithinmathewjoji
- License: mit
- Created: 2025-02-27T15:57:32.000Z (over 1 year ago)
- Default Branch: master
- Last Pushed: 2025-04-27T10:14:49.000Z (about 1 year ago)
- Last Synced: 2025-04-27T11:25:44.444Z (about 1 year ago)
- Topics: circuit, esp32, funproject, pcb, pcb-design, pcbwatch, rtc-module, schrodingers-cat, tp4056, watch, wearable-devices
- Language: HTML
- Homepage: https://nithinmathewjoji.github.io/Schrodinger-Clock-PCB-Watch-/
- Size: 6.21 MB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Security: SECURITY.md
Awesome Lists containing this project
README
# Schrödinger Clock - Open Source Smartwatch (Prototype⚠️)
Sponsored By
*A compact, open-source smartwatch powered by the ESP32-S3-WROOM with real-time clock, battery monitoring, and USB charging.*
---
## 📑 Index
1. [Introduction](#introduction)
2. [Features](#features)
3. [Hardware Overview](#hardware-overview)
4. [Sponsorship and Support](#Sponsorship-and-Support)
5. [Schematic & PCB Design](#schematic--pcb-design)
6. [Known issues & Fix](#Known-issues-and-Fix)
7. [Bill of Materials (BoM)](#bill-of-materials-bom)
8. [Firmware & Software](#firmware--software)
9. [Assembly & Soldering Guide](#assembly--soldering-guide)
10. [Usage Guide](#usage-guide)
11. [Power Management](#power-management)
12. [Downloads](#downloads)
13. [Firmware](#firmware)
14. [Visit Interactive BOM](https://nithinmathewjoji.github.io/Schrodinger-Clock-PCB-Watch-/)
15. [Contributing](#contributing)
16. [License](#license)
17. [Acknowledgments](#acknowledgments)
---
## Introduction
The **Schrödinger Watch** is an ESP32-S3-based open-source smartwatch designed with a focus on **compact PCB layout**, **low power consumption**, and **modular features**. It integrates **RTC, I2C display, battery monitoring**, and a **USB charging circuit**, making it a versatile platform for wearable tech enthusiasts.
---
## Features
| Feature | Description |
|--------------------------|-------------|
| **Microcontroller** | ESP32-S3-WROOM (40-pin) |
| **Display** | I2C OLED |
| **RTC Module** | DS3231 (with alarm) |
| **Buttons** | 3 push buttons (pull-up) |
| **Buzzer** | Included for alarms and notifications |
| **Battery** | 3.7V Li-Po battery |
| **Charging Circuit** | TP4056 for Li-Po charging |
| **Battery Monitoring** | Voltage divider for ADC measurement |
| **USB Communication** | CP2102 USB programmer |
| **Power Switching** | *P-MOSFET for auto power control |
| **Protection Circuit** | Schottky diode for USB protection |
* *feature will be added on the next revision
---
## Hardware Overview
The smartwatch is designed with **SMD components** for compactness. Below is the pin mapping:
| Component | ESP32 GPIO | Function |
|------------|------------|----------|
| OLED SDA | GPIO 20 | I2C SDA |
| OLED SCL | GPIO 21 | I2C SCL |
| RTC SDA | GPIO 20 | I2C SDA |
| RTC SCL | GPIO 21 | I2C SCL |
| RTC Alarm | GPIO 11 | SQW/INT to ESP32 |
| Battery ADC | GPIO7 | Voltage divider to ESP32 Analog Pin |
| LED | GPIO 2 | Status Indication |
| LED | GPIO 3 | Status Indication |
| LED | GPIO 4 | Status Indication |
| Push Button 1 | GPIO 12 | User Input |
| Push Button 2 | GPIO 13 | User Input |
| Push Button 3 | GPIO 22 | User Input |
* refer circuit [Schrödinger_Watch_schematics](https://github.com/nithinmathewjoji/Schrodinger-Clock-PCB-Watch-/blob/master/Schematics/schematic.pdf) for more detailed pin out.and pin assignments
---
## Sponsorship and Support
### 🙏 Thank You, PCBWay!
This project was proudly sponsored by [**PCBWay**](https://pcbway.com/g/D6Z94Y).
Their support in fabricating the custom PCB for the Schrödinger Watch has been invaluable. The quality, precision, and delivery speed were exceptional — and I’m extremely grateful for their contribution to the maker and open-source community.
If you're looking for reliable PCB prototyping, assembly, or 3D printing services, I highly recommend [**PCBWay**](https://pcbway.com/g/D6Z94Y).
## Schematic & PCB Design
The Schrödinger Watch PCB was designed using **KiCad**. The schematic consists of:
- ESP32-S3-WROOM microcontroller
- RTC DS3231 with backup battery support
- Power management with TP4056 and P-MOSFET
- I2C OLED display
- Battery voltage detection circuit
- USB programmer (CP2102)
**PCB Highlights:**
- **2-layer compact design**
- **Optimized power trace routing**
- **Thermal relief for heat dissipation**
- **Dedicated test points for debugging**
---
## Known issues and Fix
Schrödinger Watch ⌚ – ESP32-S3 DIY Smartwatch
This is the **Schrödinger Watch**, a DIY smartwatch powered by the **ESP32-S3-WROOM**. It's a fully open-source hardware project, designed and assembled from scratch, with a focus on learning, hacking, and creativity.
> ⚠️ **Note:** This is **Rev 1** of the hardware. While functional, it contains some known hardware issues listed below. A refined **Rev 2** is under development and will be released by **September 2025** with additional features and improved reliability.
These are hardware issues identified after assembly and testing:
1. **Missing CE Connection on TP4056:**
- ⚠️ The CE (Chip Enable) pin was left floating, causing the charging IC to remain disabled.
- ✅ *Fix:* A patch wire has been added to tie CE to GND manually.
2. **AMS1117 3.3V LDO Lacks Input/Output Capacitors:**
- ⚠️ Without these caps, voltage regulation is unstable (outputting ~2.4V instead of 3.3V).
- ✅ *Fix:* Patch capacitors (10µF input, 22µF output) have been manually added close to the LDO pins.
3. **No Pull-Down Resistors for Pushbuttons:**
- ⚠️ Causes GPIO pins to float, leading to erratic behavior.
- ✅ *Fix:* External 10kΩ pull-down resistors were added to stabilize the inputs.
4. **Soldering Considerations:**
- The board is fully designed with **SMD components** for a compact layout.
- All components were **hand-soldered** using a soldering iron, without hot air or reflow equipment. Minor imperfections exist, but the board is fully functional.
---
# What's Coming in Rev 2 (ETA: September 2025)
Rev 2 will be a major update with all hardware issues addressed and new features, including:
- ✅ Proper power rail decoupling and CE management
- ✅ Integrated **MPU6050** IMU for motion sensing
- ✅ Improved button input system
- ✅ Compact routing
- ✅ Better power management and battery indication
- ✅ Optional haptic feedback (planned)
- ✅ Additional user-customizable GPIOs
📌 Disclaimer
This is a learning-oriented DIY project and should not be considered a finished consumer product. Use with care and contribute to make it better!
## Bill of Materials (BoM)
| Component | Quantity | Specification |
|-----------|----------|--------------|
| ESP32-S3-WROOM | 1 | 40-pin module |
| OLED Display | 1 | I2C, 128x64 |
| DS3231 RTC | 1 | Real-time clock module |
| Li-Po Battery | 1 | 3.7V, 500mAh |
| TP4056 Module | 1 | Battery charger |
| CP2102 | 1 | USB-to-serial |
| Buzzer | 1 | 3V piezo |
| Push Buttons | 3 | Momentary switch |
| Resistors & Capacitors | Various | SMD components |
---
## Firmware & Software
The firmware is written in **Arduino** using the ESP32 library. It supports:
- RTC time synchronization
- OLED display updates
- Battery monitoring
- Button interactions
- Alarm system with buzzer
---
## Assembly & Soldering Guide
### Tools Required:
- Soldering iron with fine tip
- SMD soldering paste
- Hot air reflow station (optional)
- Multimeter for testing
### Assembly Steps:
1. Solder the **ESP32-S3-WROOM** module first.
2. Attach **RTC DS3231** and connect alarm pin to ESP32.
3. Solder **resistors, capacitors, and power circuits**.
4. Mount **OLED display** and ensure I2C connectivity.
5. Connect **battery and charging module**.
6. Flash firmware and test.
---
## Usage Guide
### Powering On:
Press and hold the power button. The watch will display the **time, battery status**, and active alarms.
### Setting Time:
Use the **serial monitor** to set the time in RTC using `setTime()`.
### Battery Monitoring:
Battery percentage is displayed on-screen and can be accessed through the serial monitor.
### Alarm Function:
The RTC alarm triggers a buzzer sound at the set time.
---
## Power Management
- **Automatic Power Switching:** P-MOSFET allows seamless switching between USB and battery.
- **USB Protection:** Schottky diode prevents reverse current flow.
- **Low Power Mode:** ESP32 enters deep sleep when inactive to conserve power.
---
## Downloads
- **Download KiCad files:** [Schrödinger_Watch.kicad_pcb](https://github.com/nithinmathewjoji/Schrodinger-Clock-PCB-Watch-/tree/master/KiCAD-Files)
- **Download Code:** [Schrödinger_Watch.ino](path_to_file)
- **Schematics:** [Schrödinger_Watch_schematics](https://github.com/nithinmathewjoji/Schrodinger-Clock-PCB-Watch-/blob/master/Schematics/schematic.pdf)
---
## Firmware
🛠️ Libraries Used
- [U8g2](https://github.com/olikraus/u8g2)
- [RTClib](https://github.com/adafruit/RTClib)
Install via Arduino Library Manager or PlatformIO.
🚧 Known Hardware Issues (Rev 1)
- ❌ No CE connection to TP4056 (manually patched)
- ❌ No input/output capacitors on MIC39100/AMS1117 LDO (caused unstable voltage)
- ❌ No pull-down resistors for switches (using `INPUT_PULLDOWN` in firmware)
The current version of the firmware is a minimal working build to demonstrate the core functionality of the Schrödinger Watch. Several features are not yet implemented:
- ❌ Push Buttons are read but not interfaced with any logic or user interaction yet.
- ❌ RTC Alarm Interrupt is connected (GPIO 11), but not yet used in the firmware.
- ❌ ESP32 Deep Sleep functionality is not implemented.
These features will be added in the next firmware updates as part of the development toward Rev 2 and in between the current development , revision 2 of this watch expected by September 2025.
# 💾 Firmware Code
```cpp
#include
#include
#include
// this code works but to be honest there is a lot of places to improve , like switch are just interfaced but not given any function , but can be done like to set time etc etc ......
// all issues will be fixed as a progress please bare with me , but if you have the knowledge then happy to recieve help
// I2C Pins
#define SDA_PIN 20
#define SCL_PIN 21
// GPIO Definitions
#define LED_PIN 2
#define BATTERY_ADC 7
#define RTC_ALARM_PIN 11
#define BUTTON1 12
#define BUTTON2 13
#define BUTTON3 14
U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);
RTC_DS3231 rtc;
void setup() {
Serial.begin(115200);
Wire.begin(SDA_PIN, SCL_PIN);
u8g2.begin();
pinMode(LED_PIN, OUTPUT);
pinMode(RTC_ALARM_PIN, INPUT);
pinMode(BATTERY_ADC, INPUT);
pinMode(BUTTON1, INPUT_PULLDOWN);
pinMode(BUTTON2, INPUT_PULLDOWN);
pinMode(BUTTON3, INPUT_PULLDOWN);
if (!rtc.begin()) {
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_ncenB08_tr);
u8g2.drawStr(0, 20, "RTC Not Found");
u8g2.sendBuffer();
while (1);
}
if (rtc.lostPower()) {
rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
}
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_6x10_tr);
u8g2.drawStr(0, 10, "Schrodinger Watch");
u8g2.sendBuffer();
delay(1000);
}
void loop() {
DateTime now = rtc.now();
char timeStr[9];
sprintf(timeStr, "%02d:%02d:%02d", now.hour(), now.minute(), now.second());
float batteryVoltage = analogRead(BATTERY_ADC) * (3.3 / 4095.0) * 2; // Adjust based on divider
char voltStr[10];
dtostrf(batteryVoltage, 4, 2, voltStr);
u8g2.clearBuffer();
u8g2.setFont(u8g2_font_logisoso38_tr);
u8g2.drawStr(0, 50, timeStr);
u8g2.setFont(u8g2_font_6x10_tr);
u8g2.drawStr(0, 62, ("BAT: " + String(voltStr) + "V").c_str());
u8g2.sendBuffer();
digitalWrite(LED_PIN, !digitalRead(LED_PIN));
if (digitalRead(BUTTON1)) Serial.println("Button 1 Pressed");
if (digitalRead(BUTTON2)) Serial.println("Button 2 Pressed");
if (digitalRead(BUTTON3)) Serial.println("Button 3 Pressed");
delay(1000);
}
```
## Contributing
We welcome contributions! If you’d like to improve the watch, please:
1. Fork the repository.
2. Create a new branch.
3. Submit a Pull Request with details.
---
## License
This project is licensed under the **MIT License**. Feel free to use, modify, and distribute it with proper attribution.
---
## Acknowledgments
Special thanks to the **open-source hardware community** for inspiring this project!