Keys? No more! The future of car access systems is here

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Keys? No more! The future of car access systems is here [Copy link]

 

As automotive design engineers begin to adopt technologies widely used in other industries, the way drivers enter their cars has become increasingly convenient. Throughout the industry's development, people used to use mechanical keys to unlock their vehicles, and then there were push-button remote control keys. Now, the most common method of car entry is the passive entry/passive start (PEPS) system, which allows drivers to enter their cars and start the engine without using a key.

How the PEPS system works

The PEPS system helps the car understand the driver's intentions and authenticate the driver's identity through radio frequency (RF) communication between the car and the remote control key. Low frequency (usually 125 kHz or 134 kHz) and ultra-high frequency (UHF) (usually Sub-1 GHz) signals transmit unique key access codes between the remote control key and the vehicle. The car will only allow the driver to unlock the vehicle if the exchanged code matches the expected value and the remote control key is within the effective distance of unlocking the vehicle.

This verification method between the remote key and the vehicle detects both position and distance, and determines whether the key is inside or outside the car. If the key is close but still outside the car, the car will enable passive access instead of passive start.

PEPS systems can be either triggered systems, where the driver initiates the entry process by touching a vehicle part (such as a door handle), or polled systems, where the vehicle entry system continuously scans within a short distance, searching for the key.

The following diagrams illustrate the entry sequence in triggered and polled systems respectively.

Unlocking the door triggers the PEPS entry sequence

Polling PEPS entry sequence to unlock the doors

Using Bluetooth Low Energy to realize “phone as key”

Today’s designers are taking the industry a step further by implementing PEPS systems using the phone as a key.

Enabling PEPS in Phone as Key Systems

The development of the “phone as a key” also includes the use of Bluetooth low energy technology instead of UHF. There are many reasons for this: the Bluetooth low energy standard is more widely used than UHF; the communication is more standardized and more secure; and the Bluetooth system consumes less power than UHF.

Bluetooth low energy technology is now used in smartphones, and the development of a car access control system based on Bluetooth low energy technology will enable smartphones to be used in PEPS systems. With the popularization of the "phone as key" system, drivers are gradually reducing their dependence on car keys, and they can even leave their keys at home. We sincerely hope that this day will come soon.

Automotive Bluetooth Low Energy Car Access Satellite Node Reference Design

This design is for a Passive Entry Passive Start (PEPS) car access system that uses Bluetooth Low Energy (BLE) technology to determine the location of a key fob. This design demonstrates how to use an automotive BLE satellite node to calculate the angle of arrival (AoA) of a BLE signal and transmit the AoA data over a local interconnect network (LIN) using a single BLE wireless microcontroller and LIN transceiver. In addition, this design shows that using only two dipole antennas, the AoA information can be accurately calculated while reducing the printed circuit board (PCB) solution size.

Click here to view the Automotive Bluetooth Low Energy Car Access Satellite Node Reference Design.

(Article source: TI E2E Community ID: Kevin Chen1)