The wireless car alarm system design
Posted on | January 10, 2012 | Comments Off
The wireless car alarm system design
With the rappid development of the automobile industry, the private car is owned by many families. But the garage can’t meet the needs in quantity. Thus, it’s the great concern of the car owner to avoid the car theft. Now the new technology wireless car alarm systems appear one after another. And the embedded system will become unavoidable.
The embdded car alarm system increases the control ability. It also reduces the volume to make the device more flexible. It creates the space for increasing the function of the car electronics in the future.
Hardware component of the system
The system is composed of the ARM embedded control, mobile module, wireless remote control and inspection module.
The car control and inspection module will collect the car related data to the ARM embedded control. The embedded controller will deliever it to the mobile module and wireless remote module.
Control circuit
If the thief causes the vibration because of the abnormal start-up, the vibration sensor will transmitt the signal to the LPC2210. Then LPC 2210 will send the inoformation to the alarm circuit and TC35. The alarm circuit is composed of circuit board, speaker and SCR. The triode or bimetal tube is to increase the efficiency. The SCR is the electronic switch made of controlled sillicon. The capacity and resistance make the step down transformer and the filter.
The power interface design
The working voltage is 3.3-5V. In the process of login the network, the current is required to be 2A.
The voltage decrease should be less than 400mV. In the module power supply design, the voltage decrease should be considered. The voltage should be higher thatn 3V. What’s more, in the data transmitting process, the voltage fluctuation should be less than 400mV. Otherwise, TC35 will turn off the module because of the low voltage. Thus, the circuit cable should be as short as possible.
The wireless serial interface
The GSM module and system processor exchange the data through the serial cable. All the operation high level voltages are CMOS (2.65V). The RS 232 translation chip should be the low voltage 3.3V.
SIM interface design
There is a complete SIM interface in the baseband processor of GSM module. The interface meets the ISO78163 standard. In order to ensure the high stability, the length between the ZIF connector and the pin should be within 200mm. The SIM groundwire processing is another problem. Of course, there are different ways as to the personal habit and style. The final goal is to achieve a separate groundwire for SIM connector.
Wireless remote module design
The wireless remote function is realized by the SRWF-1 module. It’s controlled through 89C51. The information received by C51 will be sent to the SRWF-1 transmitting module through the serial port. And the SRWF-1 will transfer it to LPC2210 through serial port.
To control the car alarm system with the GSM message can increase the reliability of the alarm. And the communication distance is not limited. The real time long distance monitoring is realized.
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