About Huaxin

Fake Bluetooth plan of burglar alarmApplication scheme

Brief introduction

Replace the traditional 433/315m wireless physical remote control. When the customer forgets to bring the key or remote control, open the mobile app to start the electric car, lock and other functions. The main functions are: anti-theft, disarm theft, car search, electric start...etc., more car borrowing function than traditional remote control.The reason why it named Fake Bluetooth is that it doesn't need to be connected (even for the first time), and it can be used directly by turning on Bluetooth.

APP

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Principle of Fake Bluetooth circuit and PCB:

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Traditional burglar alarm upgrade to fake Bluetooth plan: 

1、 The main control program of the burglar alarm hardly needs to be changed,only remote control key value need to be changed.It's also ok not to change it.

2、 PCB board embedded with fake Bluetooth chip HS24G3311 circuit,refer to schematic diagram.

Traditional burglar alarm upgrade to fake Bluetooth plan: 

2.4GHz RF applications attention points

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1、 L1 and L2 reserved inductance, normally, it can be replaced by two 0 ohm resistors, If you want to adjust the antenna to match, you can replace the 0 ohm resistance at these two positions with inductance.

2、 R1 is 0 Ω jumper resistance.

3、C1 is the reserved capacitance.

4、 For 24MHz crystal, cl=12pf, 10ppm is recommended.

HS24G3311 Resources

2K*16bits in-built ROM

128*8bits in-built SRAM

128*8bits in-built EEPROM

3-way timer: 1*8bit, 1*12bit, 1*16bit

3-way 12 bit PWM with dead band control, 3-way 12 bit PWM

5-channel touch key module

Frequency range: 2400-2482MHZ, provides 80 channels

Maximum data rate: 1Mbps

Maximum output power: 7dBm, the sensitivity can reach -98dbm(62.5kbps)

Support 2M high-speed IIC communication

Support frequency hopping

Transmit mode power consumption: 26mA(5dbm)

Receive mode power consumption: 15mA

Sleep mode low power consumption: Within 5uA (3.3V)

VDD: 2.4V-3.7V

Working temperature: -20℃~+85℃

Under normal configuration(Transmit power7dBm/62.5kbps), the  communication distance in open areas is 100 meters.

Support BLE broadcast transceiver

SOP16 Package

2.4GHz antenna

Use standard 2.4GHz antenna

The specific dimensions of the standard 2.4GHz antenna are shown in the right figure(The plate is made of two layers of FR4, with a thickness of 1.0mm),If the thickness and size of the board are inconsistent with this(Plate thickness and ground area affect performance), then the antenna end size needs to be lengthened during layout, For example, increase the length of the last 4.8m for antenna debugging. The size of the RF module board made of this antenna is about 15mm*18mm.

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