How to quickly optimize the car keyless entry system using Bluetooth low energy and LIN technology?

Continuous advances in wireless technologies such as Bluetooth Low Energy (BLE) technology and encryption standards have made keyless entry systems easier to use and effectively reduced costs, making them more popular in the automotive field. The automotive BLE market covers a wide range of applications such as keyless entry systems based on BLE technology, tire pressure monitoring systems (TPMS) and wireless battery management systems (WBMS), and its scale is expected to continue to expand. The vehicle access control market is expected to continue to grow at a steady compound annual growth rate (CAGR) until 2027 (see Figure 1). These systems have gradually become standard configurations for mid-range and above models, not only enhancing anti-theft security, but also simplifying the user experience through high integration, which is an indispensable key feature in the development of vehicle access control.

Figure 1: Automotive Bluetooth Low Energy Market Forecast (Source: Omdia)

Bluetooth low energy technology combines excellent energy efficiency and secure communication capabilities, and more and more automotive companies are using it to build keyless entry systems. The low power consumption characteristics of Bluetooth low energy extend the battery life of car keys and other portable devices, which is essential for the convenience and reliability of keyless entry systems. In addition, Bluetooth low energy also supports advanced security features, helping to prevent relay attacks and ensure that only authorized users can enter and start the vehicle.

The Local Interconnect Network (LIN) is a serial network protocol established in the late 1990s by a consortium of European automobile manufacturers and technology providers. It is a cost-effective, low-speed alternative to complex systems such as the Controller Area Network (CAN) for managing communications between devices within a vehicle. The LIN architecture supports up to 15 peripherals from a single controller, making it ideal for managing simple sensors and actuators in modern vehicles. Today, despite challenges such as declining production volumes in the automotive industry, the LIN protocol remains an integral part of vehicle communication systems, and its market is expected to grow steadily, reflecting its long-term importance to the automotive electronics sector.

ON Semiconductor has developed a reference design that delves into the complexity of optimizing the design of a keyless entry system for cars, using ON Semiconductor solutions that combine Bluetooth low energy and LIN (Local Interconnect Network) technology. This reference design integrates a number of advanced technologies to simplify the communication between the vehicle and the keyless entry system, ensuring a user-friendly and seamless experience. In addition to the robustness of the technology, the design also pays special attention to the efficiency and reliability of the system, which are also priorities in the automotive field.

Figure 2: Example of an advanced car access anchor + sniffer system

This reference design uses the automotive-grade NCV7428 system basis chip (SBC) with a LIN transceiver. The internal logic, combined with the provided software library, can be used to implement LIN 2.x compliant communication between two programmable devices. We demonstrate the use case of two peripherals corresponding to the sniffer (PEPS system) and communicating with the anchor device over the LIN bus. The LIN transceiver selected in this design uses a 3.3 V internal low dropout (LDO) regulator to not only supply power but also protect loads up to 70 mA. This allows developers to power the RSL10 evaluation board directly from the LIN bus, significantly reducing the overall system cost.

ON Semiconductor's automotive portfolio includes system-on-chips (SoCs), such as the NCV-RSL10 (Bluetooth LE 5.0) and the new automotive NCV-RSL15 (Bluetooth LE 5.2), which have the lowest power consumption in the ultra-low power (ULP) energy efficiency benchmark EEMBC ULPMark®-CoreProfile and ULPMARK-CoreMark tests. These Bluetooth low-power SoCs have been certified for automotive standards and are ideal for car access systems and WBMS. In addition, they are supported by a wide range of software development kits containing projects and code examples to help quickly develop Bluetooth low-power applications.

Figure 3: Bluetooth low energy + LIN anchor/sniffer demonstration system test bench (left) and block diagram (right), with test results included in the reference design

The following are the minimum specifications for car access Bluetooth low energy devices:

The Car Connectivity Consortium (CCC) standard has greatly promoted the popularization of keyless entry systems by establishing a common framework for digital keys. The standard enables mobile devices to securely store, authenticate and share digital keys for vehicles, thereby improving convenience and security. The CCC's approach uses near-field communication (NFC) and ultra-wideband (UWB) technologies to make it easier for consumers to enter and start their vehicles using smartphones, thereby accelerating the transition from traditional car keys to digital solutions.

Figure 4: Functional block diagram of CCC software (Source: CCC)