Car keyless entry and start system solution based on NXP products

On December 14, 2021, a leading distributor of semiconductor components dedicated to the Asia Pacific market —WP Holdings announced that its subsidiary World Peace has launched a car keyless entry and start system solution based on NXP S32K144, NJJ29C2, NCF29A1 and NCK2912 chips.

Figure 1 – The display board of the PEPS keyless entry and start system solution based on NXP products

Under the iteration of various technologies, automotive applications are innovating at an unimaginable speed. Among them, the research and development of the car keyless entry and start system, referred to as PEPS (Passive Entry Passive Start) system, not only brings convenience and comfort to car owners, but also further improves car safety. The system consists of controllers, radio frequency (RF) transmitters and receivers. When the key is within the effective range, the owner pulls the door or presses a key to start the switch, and the corresponding module will send a terminal signal to wake up the main controller and start the entire communication process. And in the process, you can open the door or start the engine without using the key.

The car keyless entry and start system solution based on NXP’s S32K144 main control MCU, NJJ29C2 low-frequency driver, NCF29A1 chip and NCK2912 UHF receiver can provide customers with excellent car experience.

Figure 2 – The block diagram of the PEPS keyless entry and start system solution based on NXP products

The main control chip S32K144 of this solution is an automotive-grade general-purpose MCU launched by NXP based on the ARM Cortex-M4F core. This product has a DSP instruction set and a single-precision floating-point processing unit (FPU). The highest frequency can run up to 112MHz. It has extremely high computing capabilities and can provide computing capabilities equivalent to the 150MHz PowerPC e200z4 core. In addition, S32K144 can provide rich peripheral interfaces and functional scalability.

In terms of low-frequency drive, the NJJ29C2 used in this solution is a base station chip suitable for keyless entry/start (PKE/PKG), which has 5-9 built-in LF drivers and has a very high start-up capability. And support the wake-up input (WUP) function related to the battery voltage. These functions are used to connect the door handle interface to the LF base station to ensure a short delay between door handle and LF transmission.

In addition, this solution embeds the NCF29A1 chip in the smart key terminal. The chip uses the HVQVN32 package to combine the keyless system (PKE), the remote control radio frequency transmitter and the anti-theft locking system together, which can realize a new smart phone and smart watch. key shape and form factor to support complete car access systems via mobile devices. And on the automotive side, the solution uses the NCK2912 high-frequency receiver to ensure real-time communication.

Figure 3-Scenario application diagram of PEPS keyless entry and start system solution based on NXP products

With the use of these high-performance devices, this solution can realize functions such as car key ID storage, keyless entry (PKE), keyless start (PKG), car immobilizer (IMMO), and remote control (RKE).

Core technical advantages:

Integrated dual IMMO function, supporting up to 9 LF antennas;

Can transmit encrypted high-frequency signals, the maximum LF drive current is 2.5A;

NCF29A1 has superior LF (low frequency) sensitivity, low power consumption up to uA level;

The key can be located by RSSI, which conforms to the HT-3 encryption protocol;

Support RF frequency hopping communication.

Program Specifications:

Realize the complete IMMO/PKE/PKG/RKE functions of the base station, and display the status on the Display;

Realize the display of RSSI value;

Antenna diagnosis and impedance test, and display results, support SWD interface;

The PKE communication distance between the key and the base station can be 3-4m;

The communication distance between the key and the base station RKE can be more than 20m.