What sensors are used in this design?

Analog Devices DS3231M High-Precision RTC

How many components are in the bill of materials?

This design's BOM has 4 components.

A vintage-inspired pocket watch powered by an ESP32-C3 Super Mini and TM1637 7-segment displays, featuring a rechargeable LiPo battery with USB-C charging.

Кирилл БреславецOct 10, 2026

POWER

MCU

DISPLAY

SENSOR

POWER_MGMT → MCU_COREPower
Provides regulated 3.3V operating voltage to the MCU
POWER_MGMT → DISPLAY_DRIVERPower
Provides power supply for the LED display driver module
POWER_MGMT → RTC_TIMEPower
Provides power to the real-time clock module
MCU_CORE → DISPLAY_DRIVERGPIO
Custom 2-wire serial interface for controlling the 7-segment display
MCU_CORE → RTC_TIMEI2C
I2C bus for querying precise time data from the RTC

Part number	Type	Component	Manufacturer	Package	Qty	Datasheet	Match
TP4056	POWER	TP4056 USB-C LiPo Charger Breakout with 3.3V LDO Manages single-cell LiPo battery charging via USB-C and provides regulated 3.3V system power	Nanjing Top Power ASIC Co., Ltd.	—	1	PDF	Matched
ESP32-C3	MCU	Espressif ESP32-C3 Super Mini Central system control, timekeeping calculations, WiFi and BLE connectivity	Espressif Systems	32-VFQFN Exposed Pad	1	PDF	Matched
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TM1637	DISPLAY	TM1637 4-Digit 7-Segment Display Module (Amber/Orange LED) Displays vintage-styled HH:MM time and system status using a 2-wire serial interface	TM	SOP20	1	PDF	Matched
DS3231M	SENSOR	Analog Devices DS3231M High-Precision RTC Maintains accurate timekeeping with temperature compensation independent of MCU deep sleep	Analog Devices, Inc.	SOP16	1	PDF	Matched
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3-5 hoursIntermediate

1

Procurement & Preparation

Gather all electronic modules including the TP4056 USB-C LiPo Charger Breakout, Espressif ESP32-C3 Super Mini, TM1637 4-Digit 7-Segment Display Module (Amber/Orange), and Analog Devices DS3231M High-Precision RTC module along with a compatible single-cell 3.7V LiPo battery.
Prepare 24 AWG hookup wires by cutting them into appropriate lengths and stripping 3mm of insulation from each end for inter-module wiring.

2

Hardware Assembly & Wiring

Solder power distribution lines from the TP4056 breakout 3.3V and GND outputs to the VCC/3V3 and GND pins of the ESP32-C3 Super Mini, TM1637 display, and DS3231M RTC module.
Connect the I2C communication interface by wiring the SDA and SCL pins from the ESP32-C3 MCU Core to the corresponding SDA and SCL pins on the DS3231M RTC module.
Connect the display interface by wiring two available GPIO pins from the ESP32-C3 Super Mini to the DIO and CLK pins on the TM1637 7-segment display module.
Connect the single-cell LiPo battery to the B+ and B- terminals of the TP4056 USB-C charger breakout module.

3

Firmware Setup

Install the Arduino IDE and add the ESP32 board package support, along with the TM1637Display library and RTClib via the Library Manager.
Write and upload the smart pocket watch firmware to the ESP32-C3 via USB-C, implementing time fetching from the DS3231M via I2C, time formatting for HH:MM, and data transmission to the TM1637 display.

4

Testing & Calibration

Perform a continuity and voltage check using a multimeter across all VCC and GND rails to verify a stable 3.3V output from the TP4056 LDO before powering the assembled circuit.
Plug a USB-C power source into the TP4056 charger module to verify battery charging functionality and observe the amber/orange TM1637 display turning on to show the correct HH:MM time.
Calibrate and sync the DS3231M RTC time via the ESP32-C3 serial monitor or network time protocol (NTP) over WiFi, then verify timekeeping accuracy over a 24-hour period.

ESP32-C3 Retro Pocket Watch

A vintage-inspired pocket watch powered by an ESP32-C3 Super Mini and TM1637 7-segment displays, featuring a rechargeable LiPo battery with USB-C charging.

Design Overview

Item	Details
Product Type	Smart Pocket Watch
Key Functions	Standard timekeeping, Vintage-meets-modern aesthetic display using four 7-segment displays, TM1637 driver integration, Rechargeable LiPo battery power with onboard USB-C charging
Power Source	Li-Ion Battery
Connectivity	WiFi, Bluetooth
Size	Standard pocket watch size with a traditional hinged case design
Environment	wearable
Difficulty	Intermediate
Est. Time	3-5 hours

System Architecture

Power Topology: A single-cell 3.7V LiPo battery connects to the TP4056 USB-C charger breakout module, which steps down and regulates power to a stable 3.3V rail feeding the ESP32-C3 Super Mini, TM1637 display module, and DS3231 RTC.

Module List

Module ID	Type	Name	Function	Voltage
POWER_MGMT	POWER	TP4056 USB-C LiPo Charger Breakout with 3.3V LDO	Manages single-cell LiPo battery charging via USB-C and provides regulated 3.3V system power	3.7V
MCU_CORE	MCU	Espressif ESP32-C3 Super Mini	Central system control, timekeeping calculations, WiFi and BLE connectivity	3.3V
DISPLAY_DRIVER	DISPLAY	TM1637 4-Digit 7-Segment Display Module (Amber/Orange LED)	Displays vintage-styled HH:MM time and system status using a 2-wire serial interface	3.3V
RTC_TIME	SENSOR	Analog Devices DS3231M High-Precision RTC	Maintains accurate timekeeping with temperature compensation independent of MCU deep sleep	3.3V

Design Schemes

Super Mini Breakout & TM1637 Module Scheme ★

Utilizes the requested ESP32-C3 Super Mini breakout board and a standard 4-digit TM1637 7-segment display module, wired together inside a hinged pocket watch case alongside a small LiPo cell and USB-C charger breakout.

Trade-offs: Lowest cost and fastest assembly using off-the-shelf breakout boards, but creates mechanical space constraints inside a traditional pocket watch case.

Custom Rigid-Flex PCB Scheme

Integrates the ESP32-C3 QFN chip, discrete TM1637 driver IC, and power management directly onto a circular rigid-flex PCB designed specifically to fit the mechanical constraints of a traditional pocket watch chassis.

Trade-offs: Higher upfront engineering cost and custom PCB fabrication time, but offers the best space utilization and thinnest profile for a true pocket watch form factor.

Key IC selection

Central system control, timekeeping, and wireless connectivity

Need: Low-power 32-bit RISC-V microcontroller with integrated Wi-Fi/BLE and compact form factor for pocket watch enclosure
Class: Module / SoC
Shortlist: Espressif ESP32-C3-MINI-1 module, Espressif ESP32-C3 Super Mini breakout
Pick: Select fully certified surface-mount module variant (ESP32-C3-MINI-1) for production BOM to ensure FCC/CE compliance and reliable RF performance.

High-precision independent real-time clock

Need: I2C real-time clock with integrated MEMS resonator or crystal compensation for high timekeeping accuracy without continuous MCU polling
Class: I2C RTC IC
Shortlist: Analog Devices DS3231M, Microchip MCP79410
Pick: Select DS3231M in SOIC package for ±5 ppm accuracy and internal MEMS resonator eliminating external crystal matching issues.

LiPo battery charging and 3.3V regulation

Need: Linear 1-cell LiPo battery charger with USB Type-C input support and low-quiescent-current 3.3V LDO regulator
Class: Linear LiPo Charger + LDO
Shortlist: TP4056 + ME6211, MCP73831 + RT9013
Pick: Select standalone linear charger IC (e.g., TP4056 or MCP73831) paired with an ultra-low Iq 3.3V LDO (e.g., Torex XC6206 or RT9013) to maximize deep-sleep battery life.

Risk register

ID	Area	Severity	Detail	Mitigation
r1	power	high	Amber/orange 7-segment LED displays driven via TM1637 draw significant current (tens of milliamps per segment), which will rapidly drain a small pocket-watch LiPo battery if left fully illuminated continuously.	Implement aggressive display power-saving firmware: dim PWM brightness levels, use a 'wrist-tilt' or button-press wake gesture to activate the display momentarily, and keep it off during deep sleep.
r2	emi	med	The compact metal pocket watch enclosure can act as a Faraday cage, attenuating the ESP32-C3's 2.4 GHz Wi-Fi/BLE antenna performance and causing connectivity drops.	Ensure the enclosure design incorporates a non-conductive window (e.g., plastic or glass front/back bezel) directly over the ESP32-C3 module's on-board PCB antenna zone.
r3	thermal	med	Linear charging via TP4056 in a confined pocket watch chassis can generate localized heat during high-current fast charging (e.g., set to 1A default).	Configure the TP4056 charge current programming resistor (R_PROG) for a lower charge current (e.g., 200mA - 300mA) suitable for small-capacity LiPo cells, reducing thermal dissipation.

Key Components

4/4 modules matched to real parts. See the BOM tab for the full component table.

TP4056 USB-C LiPo Charger Breakout with 3.3V LDO (TP4056)

The candidate matches the primary MPN TP4056 from Nanjing Top Power ASIC Co., Ltd., which is the correct manufacturer fo

Espressif ESP32-C3 Super Mini (ESP32-C3)

The ESP32-C3-MINI-1-N4 directly incorporates the ESP32-C3 primary MPN and matches the module description of the 'ESP32-C

Build Summary

Difficulty: Intermediate
Estimated time: 3-5 hours
Tools required: Soldering iron, Solder wire (lead-free), Wire stripper, Multimeter, USB-C cable, Computer with Arduino IDE

See the Build tab for the full step-by-step assembly guide.

Generated by YuanQi AI Design System · Query: Pocket watch powered by ESP32-C3 Super Mini and four 7-segment displays driven via TM1637.

Overview

System architecture

Bill of materials

Build guide