Bluetooth Car Key
A Bluetooth car key is an advanced automotive key technology that utilizes Bluetooth technology to communicate with the vehicle. Typically, a Bluetooth car key can pair with the vehicle’s internal Bluetooth system, allowing users to unlock and start the car using a smartphone or other Bluetooth devices, eliminating the need for a traditional physical key. This technology makes vehicle operation more convenient and intelligent.
Function Overview
The AR-2901T is a wireless microcontroller (MCU) that supports Bluetooth 5.1 low-power applications. Its very low active RF and MCU current, along with low-power mode current consumption, can provide excellent battery life and allow operation in both button battery and power supply applications.
Functional Diagram:
Basic Bluetooth Information
1. Module Basic Information1. Protocol: Supports GATT (master-slave integrated), functionally customizable.2. Transmit Power: Maximum transmit power of +6dBm.3. Antenna: Default built-in PCB onboard antenna, supports external antenna.
2. Application Scenarios: Automotive keys, fitness equipment, building automation, industrial monitoring, etc.
3. Application of Automotive Bluetooth Key1. The system consists of a master node (red square) and several slave nodes (blue squares) connected via a bus (black lines).2. The master and slave nodes use the AR-2901T module.3. The master node is placed inside the vehicle, while the slave nodes are placed on the doors, typically one on the left door, one on the right door, and one on the rear bumper.4. When the smartphone establishes a connection with the master node and authentication is successful, it wakes up the slave nodes, which then report the smartphone’s RSSI value via the bus.5. The aggregated RSSI data is sent to the app for processing.6. When the smartphone disconnects, the system goes to sleep, and the master node continues to wait for the next connection from the smartphone.
Principle and Function of Bluetooth Car Key
1. Principle and Function of Bluetooth Car Key
1. Unlocking and locking the vehicle: Using the Bluetooth digital key application to unlock the vehicle and start the engine, the smartphone can serve as a digital key;
2. Starting and stopping the engine: The Bluetooth key function allows for remote starting of the car’s engine.
3. Sharing vehicle access: You can share temporary or permanent access to the vehicle with family members or friends through the application, making it more convenient for multiple users to share the vehicle.
4. Vehicle status monitoring: The application can be used to monitor the vehicle’s status, such as fuel level, battery charge, tire pressure, etc., allowing the owner to stay informed about the vehicle’s health.
5. Anti-theft and security features: Bluetooth car key applications typically include anti-theft and security features, such as alarms and vehicle location tracking, to enhance vehicle security.
2. Module Sleep and Wake Mechanism
To operate the module, it needs to be awakened; to reduce power consumption when the module is not in use, it can be put into sleep mode.
The AR-2901T has two sleep and wake modes.
1. Sleep mode via serial port (AT+LPM=1): The module enters sleep mode automatically if there is no data communication on the serial port for more than 5 seconds; wake-up method: the first frame of data received on the serial port after sleep will exit sleep mode, and the first frame of wake-up data will be lost, which is a simple logic that saves IO pins.
2. Sleep mode via module IO pins (AT+LPM=2): Requires connecting the module WAKE_MCU and WAKE_BT pins, as shown in the AR-2901T module dimension diagram below.
WAKE_BT high level puts the Bluetooth module into sleep mode.
WAKE_BT low level wakes the Bluetooth module from sleep mode.
WAKE_MCU high level notifies the MCU to exit sleep mode.
WAKE_MCU low level notifies the MCU to enter sleep mode.
3. Dimensions
Generally, the MCU controls the module’s sleep and wake functions. If both the MCU and the module are in sleep mode, how can the MCU be awakened?
You can connect to the AR-2901T module via Bluetooth through the app; upon successful connection, the module will be awakened for 5 seconds, and the corresponding WAKE_MCU pin will be pulled high to wake the MCU. After 5 seconds, the module will automatically go to sleep.
If you do not want the module to sleep after 5 seconds, the MCU can keep the WAKE_BT pin low to wake the module, and the pin needs to be pulled high to put the module back to sleep.
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Tianli Automotive Electronics Technology Co., Ltd. Professional manufacturer of automotive antennas and electronic components in China. Main products include: automotive AM/FM/DAB radio antennas, DVB/CMMB television antennas, GNSS navigation antennas, CB radio antennas, shark fin combination antennas, automotive T-BOX antennas, mobile communication 4G/5G antennas, RTK high-precision positioning antennas, antenna amplifiers, PE/PS low-frequency antennas, high-power USB charging docks, in-vehicle wireless charging docks, and various USB data connections and FAKRA harnesses. |
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