Smartwatch PCB, Chipset, Sensor, Firmware & SDK Customization

1.Introduction

As the smartwatch industry evolves from consumer-grade gadgets to professional wearable terminals, brands increasingly require deep customization—not only appearance or UI, but the core layers of the product: PCB design, chipset configuration, sensor integration, firmware algorithm tuning, and SDK support.

Whether you are building a sports smartwatch, a corporate gift watch, a medical wearable, or an industry-specific device, understanding these five technical modules is the key to creating a stable, accurate, and differentiated product.

This guide provides a complete overview of how smartwatch hardware and software layers work together, and how OEM/ODM developers can customize them.

2. Smartwatch PCB (Printed Circuit Board) Design

The PCB is the “central nervous system” of a smartwatch. Every communication path, power line, and peripheral module is connected through it.

2.1 What the PCB Controls

·         Power management

·         Sensor connections

·         Bluetooth/GPS antenna layout

·         Display interface (AMOLED/TFT)

·         Charging circuit

·         Vibration motor, speaker, microphone

·         Button/rotary encoder signals

2.2 Why PCB Design Matters

A poorly designed PCB will cause:

·         GPS drifting

·         High standby power consumption

·         Sensor inaccuracy

·         Bluetooth disconnection

·         Overheating

·         EMI/EMC interference

2.3 Customizable PCB Options

·         Single-layer to multi-layer PCB

·         GPS L1 band optimized routing

·         Custom antenna design (ceramic/FPC/ LDS)

·         Waterproof structure adaptation

·         Custom peripheral interfaces (PPG, temperature, SpO2, ECG, NFC)

3. Smartwatch Chipset (CPU/MCU/SoC)

The chipset determines performance, battery life, algorithm capability, and display quality.

3.1 Popular Chipsets in 2025

Category	Chipset	Features
Ultra-low-power	Realtek RTL8763E	Stable, suitable for general fitness watches
Mid-range	AC/ATS series	Good balance of performance and cost
High-performance	Qualcomm W5/W5+ Gen	Advanced OS, strongest performance
Industry-grade	Nordic / STM32	Medical & industrial applications

3.2 Custom Chipset Configuration

·         CPU frequency adjustment

·         Memory selection (RAM/ROM)

·         External flash for watchfaces

·         GPS + GNSS multi-satellite support

·         Optimization for battery longevity

3.3 Why Chipset Choice Is Critical

The chipset affects:

·         Smoothness of UI animation

·         Heart rate accuracy

·         Battery life (sleep performance is key!)

·         Bluetooth connection strength

·         App compatibility

4. Smartwatch Sensor System

Sensors define the “intelligence” of a smartwatch.

4.1 Common Sensor Types

·         PPG Heart Rate Sensor

·         3-axis/6-axis accelerometer + gyroscope

·         SpO₂ Module

·         Skin Temperature Sensor

·         Air Pressure / Altitude Sensor

·         ECG Electrodes

·         GPS/GLONASS/Galileo Receiver

4.2 Sensor Customization Options

·         Replace sensor supplier (Goodix, Pixart, OSRAM, AMS)

·         Adjust sensor sampling frequency

·         Optimize algorithm + hardware matching

·         Waterproof and sweat-proof lens customization

·         Multi-sensor fusion for higher accuracy

4.3 Key Factors Affecting Accuracy

·         PPG + lens + algorithm

·         Wristband material

·         PCB + battery placement

·         Firmware filtering level

5. Firmware Customization

Firmware is the “brain” that controls all hardware.

5.1 What Firmware Controls

·         Bluetooth communication protocol

·         Sensor drivers

·         Motion algorithm

·         Display rendering engine

·         Watch UI & menu structure

·         Power management

·         OTA updates

5.2 Firmware Customization Services

·         Custom watch UI logic

·         Custom sports mode

·         Heart-rate algorithm tuning

·         SpO₂ calibration

·         Custom vibration patterns

·         Multilingual support

·         Bluetooth protocol adaptation for third-party apps

5.3 Importance of Firmware Stability

A stable firmware ensures:

·         Low crash rate

·         Long battery life

·         Accurate health data

·         Smooth animations

6. SDK (Software Development Kit) for Smartwatch Integration

For brands building their own mobile app, SDK support is essential.

6.1 What the SDK Provides

·         Bluetooth communication protocol

·         Data structure (HR, SpO₂, GPS, sleep, steps)

·         Real-time data stream

·         Command control (vibration, notification push)

·         OTA update API

·         Pairing & binding logic

6.2 Why SDK Matters

An optimized SDK helps:

·         Faster app development

·         More reliable data sync

·         Custom features:

o    Training plans

o    Medical monitoring

o    Corporate employee management

o    Fitness community features

6.3 Typical SDK Customization

·         Custom encryption

·         Cloud platform interface

·         Custom data storage rules

·         3rd-party app integration layer

7. Complete Custom Development Workflow

Below is a standard smartwatch OEM/ODM technical workflow:

1. Requirements analysis

2. Chipset selection

3. Custom PCB routing

4. Sensor selection & testing

5. Firmware development

6. UI/UX design

7. SDK + app interface

8. Sample production

9. Waterproof & aging test

10. Mass production

A full project typically takes 45–90 days depending on complexity.

8. Who Needs Deep Customization?

This type of advanced customization is ideal for:

·         Smart fitness brands

·         Wellness & physiotherapy brands

·         Medical wearable companies

·         Corporate gift projects

·         GPS outdoor brands

·         Sports coaching platforms

·         IoT companies

·         Startup brands needing unique positioning

9. Conclusion

Smartwatch customization has entered a new era.
It’s no longer about putting a logo on a watch — it’s about creating a hardware + firmware + sensor + algorithm + app ecosystem that matches your business model.

A professional OEM/ODM partner can help you reduce R&D cost, shorten development time, and build a reliable wearable product ready for global markets.