Dual NTP Clock
Dual Clock displaying local time and UTC Time using an internet connection via WIFI 2.4g to connect and retreive the time and date using the network time protocol. The unit has multiple featues such as displaying the temperature and humidty through the onboard DHT11 Sensor and also configuration is possible through the serial terminal menu. It has onboard serial to USB Interface an a Lipo charger accepting one lipo cell .
NTP Shack Clock designed around the ESP‑01/ESP‑01S module. The design transformors the ESP01 into a fully autonomous, network‑synchronized digital clock with dual displays, environmental sensing, and a robust serial‑driven configuration system. Designed specifically for the ESP‑01’s extremely limited RAM and flash resources, the firmware avoids heavy libraries and unstable WiFi managers, opting instead for a lean, deterministic architecture that guarantees stability even under poor WiFi conditions.
The clock uses two TM1637 4‑digit LED displays: one for local time and one for UTC. A DHT11 sensor provides temperature and humidity readings, which the firmware alternates with the time display at configurable intervals. Time synchronization is handled through NTP, with support for custom servers, timezone offsets, and automatic daylight‑saving adjustments for both EU and US regions.
A key design goal of this firmware is absolute reliability on the ESP‑01, a device notorious for watchdog resets when WiFi operations are mismanaged. To achieve this, the firmware uses a delayed‑startup WiFi routine, a non‑blocking state machine for configuration, and a fallback AP mode that activates only when needed. All configuration is performed through a clean, menu‑driven serial interface — no web portals, no WiFiManager, and no memory‑heavy components.
Core Features
- Display Features
- Dual TM1637 Time Displays
- Local time shown on the first display
- UTC time shown on the second
- Automatic switching between time and environmental data
- Adjustable brightness (0–7)
- 12‑hour or 24‑hour mode
- On Board USB-C to Serial circuitry
- On Board Lipo TP4056 Charger - to charge 1 cell 4.2v
- Jumper to put ESP01 in programming mode - no need to remove from board.
- Top switch to turn clock off if transporting it .
NTP Time Synchronization
Uses NTPClient for lightweight time updates
Custom NTP server support
Automatic retry logic
Timezone offset stored in EEPROM
Auto DST modes:
EU (last Sunday of March/October)
USA (second Sunday of March, first Sunday of November)
3. Temperature & Humidity Monitoring
DHT11 sensor support
Temperature displayed in °C or °F
Humidity displayed as percentage
Alternates with time every few seconds
4. Robust WiFi System (ESP‑01 Safe Mode)
The firmware uses a three‑stage WiFi strategy:
A) Delayed WiFi Startup
WiFi is not touched for the first few seconds after boot, preventing watchdog resets.
B) Manual WiFi Connection
If stored credentials exist, the ESP attempts to connect once.
C) Fallback AP Mode - if the connection fails defaults to a local Access Point.
No portal, no HTTP server
Pure AP mode for maximum stability
Allows the user to connect and configure via serial
5. Serial Configuration Menu
The firmware includes a clean, numbered menu accessible via serial at 115200 baud.
Options include:
Set timezone
Set display brightness
Toggle 12/24‑hour mode
Toggle Celsius/Fahrenheit
Set NTP server
Configure WiFi (scan → select → enter password)
Scan WiFi networks
Reset WiFi settings
Show all current settings + live time + temperature
Show NTP server
The menu is always available and never blocks the main loop.
6. Advanced WiFi Setup (Option 6)
Option 6 is implemented as a non‑blocking state machine, ensuring the ESP‑01 never freezes or resets during configuration.
The process consists of scanning for nearby WiFi networks and user selects his wifi ssid and prompts for the password where the Firmware prompts for password (30‑second timeout) and once entered the Credentials are saved to EEPROM and Device reboots cleanly.
This approach avoid any serial bugs or leftover newline characters where it might block the WiFi causing a shutdown or a watchdog resets or any accidental menu triggers,
7. EEPROM‑Backed Configuration
All user settings persist across reboots:
SSID
Password
Timezone
Brightness
Temperature unit
Hour mode
NTP server
EEPROM writes are minimized to extend flash life.
8. Watchdog‑Safe Architecture
The firmware is engineered to avoid the common ESP‑01 pitfalls:
No long blocking delays
No WiFi operations during early boot
No WiFiManager
No web server
No STA+AP mixed mode
No reconnect loops
No heavy strings in tight loops
Every subsystem is designed to keep the watchdog fed and the device stable.
9. Clean, Predictable Boot Sequence
Boot
Wait for WiFi stack to stabilize
Attempt WiFi connection
If fail → start fallback AP
Start NTP only if WiFi is connected
Begin main loop (time + sensor + menu)
This ensures the device never enters a boot loop.
10. Designed for Real‑World Reliability
This firmware is built for:
Low‑power clocks
Radio Shack Clock
Wall‑mounted displays
Network‑synced timekeeping
Environments with unstable WiFi
ESP‑01 modules with minimal RAM
It is intentionally simple, predictable, and robust. The NTP Dual Clock is a fully configurable NTP‑synchronized clock with dual displays, environmental sensing, and a rock‑solid WiFi system designed specifically to avoid watchdog resets. All configuration is handled through a clean serial interface, with a safe fallback AP mode for recovery. The architecture is optimized for the ESP‑01’s constraints, ensuring stable operation even in challenging network environments.
The NTP Dual Clock is supplied Ready built and tested - user can connect a usb cable and access the menu system with a serial terminal. A wifi connection is required for this clock to work.
| Title | Dual NTP Clock |
|---|---|
| Category | Test Equipment |
| SKU | cUeib2n |
| Condition | new |
| Weight | 80.0 g |
