As Smart Home IoT technology becomes mainstream, opportunities for developing innovative products are rapidly emerging. Smart locks are a growing category with significant innovation potential, with the global smart lock market expected to grow at a CAGR of 19.6% from 2023 to 2030.

The introduction of the Matter protocol has enhanced IoT devices with plug-and-play capabilities, enabling seamless connectivity with major smart home ecosystems, including HomeKit, Google Assistant, Alexa, and others. This evolution has made integrating smart locks into smart home systems easier, leading to trends like voice assistant control, remote access, camera integration, and advanced locking/unlocking mechanisms.

With flexible designs and the increasing adoption of home automation, smart locks have become a leading component of the connected home experience. Additionally, smart locks are becoming widespread in commercial applications such as the hospitality industry, commercial buildings, manufacturing facilities, smart cities, and lockbox facilities, making them a booming market in various sectors.

This paper will explore the basics of smart locks, key concepts, and design factors for developing smart lock technologies.

What are Smart Locks?

Smart locks are electronic door locks that combine components (circuitry) and a latching mechanism to provide secure access control solutions. Their main components are the microcontroller unit (MCU), motor driver, wireless communication module, battery power management, sensors, and user interface components like keypads or biometric sensors.

Smart Locks are typically battery-powered IoT devices or embedded devices that require ultra-low power capabilities and use Bluetooth LE, Zigbee, Thread, Wi-Fi, and Z-Wave.

Smart Lock Design and Development

Krasamo is an IoT development company specializing in electronic product design for smart homes, building automation, and Industrial IoT.

Our engineers have experience in PCB layout, Gerber files, manufacturing processes, and testing. Our expertise also includes firmware development, embedded applications, and wireless connectivity.

We have experience developing smart home products such as locks, HVAC, sensors, toys, and building automation. We strive to create products that are easy to use, reliable, and secure.

Choosing the Right Chip for Your Smart Lock

When designing a smart lock, selecting the appropriate chip is crucial for optimizing performance, cost, and development efficiency. The right choice can significantly impact your product’s success by reducing development costs, accelerating time-to-market, and increasing overall return on investment (ROI). Here are key factors to consider when selecting a chip for your smart lock:

1. Power Management: Smart locks are typically battery-powered, so choosing a chip with excellent power management capabilities is essential to maximize battery life. Low-power consumption chips, such as those designed for Zigbee or Bluetooth LE, can extend battery life in wireless smart locks. Some smart locks, like Wi-Fi-enabled locks, require more power for continuous connectivity, and their chips must balance functionality with power efficiency. Battery Optimization: Energy-efficient design ensures long-lasting functionality for battery-operated smart locks. Developers can extend battery life by optimizing power consumption through low-power modes during inactivity and utilizing wireless protocols like Thread and Zigbee. By fine-tuning sleep modes and reducing power draw during idle periods, smart locks can operate reliably for years, reducing the frequency of battery replacements.​
2. Wireless vs. Non-Wireless: The decision between wireless and non-wireless chips depends on the use case, mostly for certain commercial or industrial settings. For example, Matter-over-Thread and Z-Wave protocols are wireless and enable smart locks to integrate seamlessly into existing home automation systems. However, a wired chip might reduce costs and simplify the design if the lock does not require remote access. Wireless solutions provide added flexibility and scalability but have higher development and power management complexity.
3. Cost vs. Volume Considerations: The cost of the chip is a significant factor, especially when considering the production volume. Choosing a low-cost chip might make sense for high-volume deployments, but this will often require higher investment in software development. Conversely, for low-volume projects, selecting a chip from a vendor that offers robust software support may be more cost-effective, reducing the time and resources needed for development.
4. Software Support and SDK Quality: Software support from the manufacturer is critical, especially for smaller projects. Selecting a robust software development kit (SDK) vendor can significantly reduce development costs. A high-quality SDK provides the tools and documentation necessary to integrate the chip efficiently into the smart lock design, making it easier for developers to focus on product-specific features​. Vendors like Silicon Labs offer extensive software support for their wireless IoT chips, which can be crucial for ensuring smooth deployment.
5. Connectivity Protocol Version: It is crucial to assess the functionality and scalability of each protocol version to ensure it meets the product’s needs without adding unnecessary complexity. For instance, BLE 4 is often chosen for its balance between quality and cost, while BLE 5 is preferred for its technological advancements, offering improved efficiency, control, and overall performance.

Smart Locks 101

In the following subsections, we will discuss some of the basics of smart locks to illustrate our readers’ exploration of digital transformation initiatives.

Smart Lock Requirements

• Low power requirement (battery-powered)
• Throughput requirements (Low for daily needs, high firmware upgrading)
• Security requirements (SSL/TLS, WPA2/WPA3)
• Cloud Connectivity–remote control
• Bluetooth Low Energy integration for provisioning to Wi-Fi network

Smart Lock Systems-Main Devices

• MCU (Microcontroller Unit): A compact, integrated circuit that contains a processor, memory, and input/output peripherals used to control the functions of embedded systems like smart locks. It acts as the brain of the device, executing software to manage operations such as locking mechanisms and wireless communication. Modern MCUs have built-in wireless capabilities, sometimes eliminating the need for separate wireless modules.
• Bluetooth Radio: A wireless communication module that allows short-range data transmission between devices using Bluetooth technology. In smart locks, a Bluetooth radio enables the lock to communicate with smartphones or other smart home devices for control and monitoring. Bluetooth Low Energy (BLE) is often used in smart locks due to its energy efficiency.
• Wireless Module: Wireless modules enable secure, cloud-based connectivity. A smart lock handles wireless communication and connects to a mobile app or web interface via Wi-Fi, enabling features such as remote access, notifications, or integration with other smart home devices.
• Motor Driver: An electronic component that controls the operation of a motor, such as in a smart lock’s locking and unlocking mechanism. It regulates the power delivered to the motor, determining its speed, direction, and torque.
• Power Management: Power management is a system function that optimizes energy use within a device to extend battery life. In smart locks, power management involves regulating how much power each component consumes, especially during idle periods, to ensure long-lasting, reliable operation on battery power.
• Locking Mechanism: The physical component secures the door, such as a deadbolt or latch.
• Sensors: Various sensors might be used, such as door position sensors, tamper detection sensors, or biometric sensors (e.g., fingerprint readers).
• User Interface: Many smart locks have some form of local interface, such as a keypad or touch panel, for manual operation without a smartphone.
• Backup Key Cylinder: Most smart locks include a traditional key cylinder as a backup in case of electronic failure or a dead battery.
• Security Chip: Some advanced smart locks include dedicated security chips for enhanced encryption and protection against hacking attempts.

Smart Lock Security and Privacy

Smart locks are about security, so it’s essential to highlight the importance of integrating end-to-end encryption and data protection to ensure that communication between the smart lock and connected devices is secure. This enhances the overall security of the smart home by protecting against potential cyberattacks.

When designing smart locks, secure data transmission should be considered to prevent unauthorized access and protect sensitive data. Specifically, encryption and secure communication protocols, such as (SSL/TLS and WPA2/WPA3) are vital for ensuring that data sent between the IoT sensor and the cloud or other devices is protected from cyber threats.

For battery-powered wireless devices, balancing between maintaining low power consumption and implementing robust security features, such as encryption algorithms, that can safeguard data without overly draining the device’s battery​.

Smart Lock Authentication Methods

As smart home technology evolves, smart locks incorporate multiple authentication methods to enhance security and convenience. Modern smart locks can have various input options that offer flexibility for users and use cases.

From traditional keypad entry to advanced biometric methods like facial recognition and fingerprint identification, each option serves unique needs in ensuring secure access control.

Additionally, smart locks now offer the possibility to implement dual or multi-authentication mechanisms, combining multiple methods for enhanced security. This section explores the key authentication methods available for smart locks:

PIN Codes: Users enter a Personal Identification Number (PIN) on a keypad to unlock a smart lock. The correct sequence must match a pre-stored code in the lock’s system, granting access.

Security Tokens: Physical or digital tokens (e.g., key fobs or smartphone apps) generate a secure, time-sensitive code or key. The token authenticates the user when presented to the smart lock, allowing access.

Biometrics: Biometrics use unique physical characteristics for authentication. Smart locks capture and analyze these traits to verify identity.

• Fingerprint: The lock scans and stores unique patterns of a person’s fingerprint. It compares the scanned fingerprint to stored data for access control.
• Hand Geometry: Measures the shape and size of the hand. The system verifies the user by comparing hand geometry against stored profiles.
• Face Recognition: Uses cameras and algorithms to map facial features. The smart lock grants access if the detected face matches the registered profile.
• Voice Recognition: This system analyzes vocal patterns and characteristics. The lock compares voice commands to stored profiles to verify identity.
• Eye Scan: Scans the iris or retina, which have unique patterns. The system matches the eye scan to pre-registered data for authentication.

Proximity-Based Access Control

Modern smart locks increasingly rely on proximity-based access control methods to enhance convenience and user experience. These methods allow the lock to detect an authorized device and automatically unlock when the user is nearby, eliminating the need for manual input.

• Bluetooth Low Energy (BLE) Proximity: The lock detects a paired device, such as a smartphone, when it comes within range (usually within a few meters) using Bluetooth Low Energy. Once in range, the lock communicates with the phone and automatically unlocks if the phone’s credentials are authenticated.
• NFC (Near Field Communication): Some smart locks use NFC to detect an NFC-enabled device (e.g., a phone or key fob) when brought close to the lock. Once proximity is confirmed, the lock can automatically unlock. In addition to proximity detection, NFC can transfer power, enabling battery-free smart locks through energy harvesting technology.
• Geofencing: This technology uses GPS or Wi-Fi to create a virtual boundary around the lock. When the user’s smartphone enters this predefined area, the lock is triggered to unlock. Geofencing smart locks often work with Bluetooth for more precise proximity detection.

Selecting the Right Wireless Protocols

Choosing the right wireless protocol is critical in the design of smart locks, as it directly impacts power consumption, range, and connectivity reliability. Protocols like Zigbee, Z-wave, Bluetooth Low Energy (LE), and Thread are often preferred for their low power consumption and ability to maintain long-term device operation on a single battery. Each protocol offers different advantages depending on the use case:

• Bluetooth LE is ideal for short-range applications where low power usage is key, such as provisioning or direct smartphone communication.
• Zigbee and Thread excel in mesh network setups, enabling extended range and multiple devices to communicate efficiently, making them well-suited for smart home applications.
• Wi-Fi is a more power-hungry option than protocols like Zigbee or Bluetooth LE. While Wi-Fi offers greater bandwidth and range, it typically requires more energy, making it less ideal for long-term battery-powered IoT devices. However, Wi-Fi is still a valid option when constant connectivity and higher data throughput are required, as seen in certain smart home applications​.
• Z-Wave operates on a low-power mesh network, allowing devices to communicate over long distances by relaying signals through other devices. It’s highly interoperable, supporting seamless integration across different manufacturers’ smart home devices, and its low power consumption makes it ideal for battery-operated devices like smart locks and sensors.

When selecting a protocol, developers must balance the device’s battery life requirements, data throughput needs, and network size to ensure optimal product lifecycle performance.

The protocol choice should align with the overall design goals, including form factor and cost considerations, as each has unique impacts on the Bill of Materials (BOM) and power management strategy.​

The Matter Smart Home Ecosystem

When discussing smart locks, it’s important to focus on the Matter-over-Thread protocol (Matter next-gen protocol), which provides a secure and interoperable connection for smart locks within the broader smart home ecosystem.

Building Matter smart home devices is an emerging trend that simplifies device integration, increases security, and future-proofs smart lock designs.

Matter-over-Thread promotes energy-efficient designs. It operates in a low-power mesh network, allowing smart locks to conserve battery life while maintaining strong connectivity with other devices in the smart home ecosystem. By using Thread as a protocol, developers can ensure that smart locks maintain robust wireless performance without draining battery resources, especially during long periods of inactivity.

Silicon Labs Smart Lock SoC’s

• Silicon Labs EFR32 Wireless Gecko SoC (System on Chip). The EFR32 Wireless Gecko series from Silicon Labs is a versatile family of wireless microcontrollers (MCUs) designed to support many IoT applications. These MCUs provide seamless integration with multiple wireless protocols, including Bluetooth, Zigbee, Thread, and Z-Wave, making them ideal for smart home products such as smart locks, lighting, and sensors. With a strong focus on power efficiency, the EFR32 series ensures extended battery life, even in devices that require constant connectivity, without compromising performance.In addition to multiprotocol capabilities, the EFR32 Wireless Gecko MCUs feature advanced security measures to protect IoT devices from cyber threats. Built-in encryption, secure boot features, and over-the-air (OTA) firmware updates ensure that devices remain secure throughout their lifecycle. This combination of low-power consumption, robust security, and multiprotocol flexibility makes the EFR32 series a top choice for developers looking to build innovative, reliable IoT solutions.
• EFR32MG21 is a Series 2 multiprotocol wireless SoC designed for smart locks, sensors, and home automation devices. It supports multiple wireless protocols, including Zigbee, Bluetooth Low Energy (LE), and Thread, allowing seamless integration into diverse smart home ecosystems. Known for its low power consumption and robust security features, the EFR32MG21 ensures reliable wireless communication while maximizing battery life in power-sensitive applications. Its advanced security includes hardware encryption, secure boot, and over-the-air (OTA) firmware updates, making it a secure and efficient choice for IoT developers.
• EFR32MG24 Series 2 Multiprotocol Wireless SoC. The EFR32MG24 SoC supports multiple wireless protocols, such as Zigbee, Bluetooth, and Thread, making it ideal for smart locks and other IoT applications. The SoC provides advanced features like low power consumption, robust security, and seamless integration with various smart home ecosystems. The SoC’s multiprotocol capabilities allow it to switch between or simultaneously support different wireless communication standards, offering flexibility and scalability for IoT devices, including smart locks.
• RS9116 Wi-Fi Transceiver Modules. The RS9116 Wi-Fi Module provides low-power consumption and Wi-Fi connectivity. It allows for remote control via mobile apps, enabling users to manage access to their homes from any location. In addition to its connectivity features, the RS9116 provides enhanced security through secure boot and encryption mechanisms, ensuring that the smart lock is protected from cyber threats. This low-power Wi-Fi and robust security combination made the RS9116 ideal for innovative smart lock solutions.
• SiWx917 The SiWx917 is a single-chip Wi-Fi 6 and Bluetooth Low Energy (LE) 5.4 wireless secure MCU from Silicon Labs. It is designed for ultra-low-power IoT wireless devices that require secure cloud connectivity. It is ideal for battery-operated applications, such as smart locks, smart home devices, and industrial IoT, where long battery life is crucial.

Key features include a dual-core design with an ARM Cortex-M4 processor for application processing and a network wireless processor (NWP) for wireless communication. The SiWx917 supports Wi-Fi 6, Bluetooth LE 5.4, and Matter protocols, providing robust connectivity options. It offers advanced security features, including hardware encryption, a secure boot, and over-the-air (OTA) firmware updates. This SoC is energy-efficient and integrates peripherals like an ultra-low-power sensor hub and matrix-vector processor, making it a powerful, versatile solution for modern IoT applications​.

Smart Lock Use Case

At Krasmo, we deployed the Silicon Labs on a low-power application to control the keypad and lights of a door lock on which the keypad had an interface with a main MCU, which managed the IoT communication and lock logic. The keypad originally worked with an always-active polling mechanism, so we upgraded it to hardware interrupts instead. The interface to the main CPU was done using a proprietary binary protocol. All this communication was also updated to work using hardware events. As a result, we could decrease the power consumption enough to make it a feasible battery-operated device.

We also implemented an OTA mechanism to update the keypad Silabs Microcontroller from the master MCU using the proprietary binary protocol.

Basic Hardware Design Documentation

When discussing electronic lock design with developers, it is important to understand the following documents:

What is the PCB Layout?

A well-designed PCB layout is the design file containing the smart lock’s functionality, reliability, and efficiency. In designing a smart lock, the PCB layout involves arranging all the electronic components, such as the microcontroller, motor driver, wireless communication modules, sensors, power management circuits, and user interface components like keypads or biometric sensors.

A good layout is critical to ensure proper placement and routing to prevent noise and signal interference, which is crucial for the reliable operation of communication modules and sensors. It also ensures effective power distribution to extend battery life and considers size constraints to ensure the accessibility of buttons and sensors.

Gerber files are a standard file format used in electronics manufacturing to describe the printed circuit board (PCB) layout, including the placement of components, traces, vias, pads, and other details necessary for production.

A Bill of Materials (BOM) is a comprehensive list in a spreadsheet or text file with all the parts, components, assemblies, and materials required to manufacture a product. It typically includes detailed information such as part numbers, quantities, descriptions, and specifications for each component used in the product’s design.

When designing a smart lock, it is essential to balance cost-efficiency (using a low-cost BOM) with the need for reliable performance and battery longevity–crucial for maintaining affordability and quality in a competitive market.

For example, in the context of electronics or smart locks, a BOM would include:

• Electronic components (e.g., microcontroller, motor driver, sensors)
• Mechanical parts (e.g., latches, casing)
• Software components (e.g., firmware, licenses)
• Miscellaneous materials (e.g., screws, adhesives)

The BOM ensures that all necessary items are available during production and helps in cost estimation, inventory management, and procurement.

IoT Consulting Services

• IoT Development
• Cloud and IoT Platform Integration
• Industrial IoT (IIoT)
• Embedded Development/Firmware development
• Build Matter Smart Home Devices
• Develop Mesh Networks