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LPC2132-based intelligent anti-tampering system design

In Electronic Infomation Category: L | on April 23,2011

Abstract: Over the years, some units, particularly in private, the theft of electricity as a means of profit, which seriously damaged the power supply enterprises legal rights, disrupted the normal order for the power, seriously affected the development of power industry, but also pose a serious threat to the safe use of electricity. To minimize the losses caused by stealing, the paper application of computer and BU2527AX datasheet and communication technology, design of intelligent anti-tamper LPC2132 based system, and BU2527AX price and do practical, market-oriented, and BU2527AX suppliers and ultimately to a large area in the power sector to promote the use of the new technology, with a strong sense of social reality.

0 Introduction

As computer technology and communication technology continues to evolve, the Internet and embedded smart devices get more and more widely used. It was a distributed control system between the nodes achieving real-time, reliable data communications to provide strong technical support, it is an effective support for real-time control of distributed control or serial communication network. This paper analyzes the LPC2132-based intelligent anti-tampering system.

1 hardware design program

Based on the above planning functions of the device can be in two parts for the device design and planning, intelligent control system consists of upper and lower machine two parts, of which the host computer by the PC machine to achieve. The next crew including the master microcontroller MSP430F149 form, 4 4 of the man-machine interface keyboard, optical and acoustic alarm circuit relay control circuit.

1.1 Sensor Selection

1.1.1 energy measurement chip select

Electricity primarily through the acquisition part to achieve energy measurement chip AD7755 collection and storage of electricity. May one day be divided into 48 time periods, that is, a time period of each half an hour, the microcontroller will be collected within half an hour and half hour the number of pulses collected the maximum power value to the database server, then the database Server real-time data updates, and the form of a dynamic web publishing out. Charge sampling circuit is the key to energy measurement circuit, shown in Figure 1.

power sample circuit in Figure 1

1.1.2 oil temperature sensor selection

Platinum resistance sensor for measuring the transformer oil temperature, the temperature measurement circuit shown in Figure 2. Transformer oil temperature sensor for measuring the oil temperature, oil temperature higher than the set value when the alarm and cut off the transformer switch.

Figure 2 Temperature Circuit

The parameters are as follows:

Measuring range: -200 ~ +850 ; allowed deviation : A class (0.15 +0.002 t ), B-class (0.30 +0.005 t ); minimum into Depth: The minimum thermal resistance into the depth of 200 mm; let-through current 5 mA.

1.1.3 Selection of oil level sensor

Use UZF2 (side mounted) remote control-type level gauge turned columns. Turned column magnetic magnetic level gauge is based on the principle of Archimedes (buoyancy), and other principles of mechanical drive a clever combination of the characteristics of a developed specifically for liquid level measurement device is in turn controlled liquid column meter based on the increase of magnetic switch, magnetic switch, while monitoring the signal level can be used to control or alarm level; FET-type level gauge in turn based on the column increased 4 ~ 20mA changes send sensor, liquid level in the field, while monitoring changes in the level through the transmission sensors, cables and instruments reached the control room, remote monitoring and control.

1.1.4 anti-tampering signals select

The entire system is powered on, the main control system and the micro-controller starts to self-test, initialization is completed, if no receiver to the remote management center through GPRS to send the command, monitoring and control system of the order of the main current and the meter reading monitoring data, measurement of transformer oil and the oil level and for data processing, to determine whether the normal door measurement, time measurement and control subsystem receives the measurement and monitoring data transmission and data processing and output control, measurement and control subsystems order simultaneously measuring current and High oil temperature magnetic kit and kit to monitor the positioning of high-pressure magnetic state of the electromagnet and the oil level. When the main system receives the remote monitoring and control management center via GPRS to send the command, to judge of instruction to determine the internal load of the transformer or disconnect switch closing instructions, or magnetic orientation kit, instructions and magnet positioning or measuring tank door release positioning solenoid positioning or release command. Master control system to send the contents of the corresponding instructions to the monitoring and output control subsystem to complete the various functions. In addition, the main control system real-time measurement of the current value and the meter reading from the current value of the two curves formed in the LCD and stored. Control circuit inside the main measure to achieve the positioning of the electromagnet control, positioning solenoid to achieve the measurement of the main door lock control, when the orientation is the direction of solenoid coil is powered, the solenoid metering positioning bolt door locks, anti- the direction of power, the solenoid release of the positioning bolt, measure door can be opened. Figure 3 shows the output control solenoid circuit.

When PTC3 and PTF6 are high, the solenoid coil is energized direction, locking door measurement can not be opened. Need to be turned, so PTF7 and PTC0 are high, solenoid release, measured door can be opened.

Figure 3, the control solenoid output circuit

1.2 Microcontroller Selection

Design architecture based on PHILIPS ARM LPC2132 chip company as a data collection terminal of the MCU. LP C2132 microcontroller is based on a real-time emulation and embedded trace support 32-bit ARM7TDMI-SCPU, and high speed with 64 kB Flash memory.

128-bit wide memory interface and a unique accelerator architecture enable 32-bit code can run at maximum clock rate. Remote data acquisition system with Ethernet network interface module connected to the task by the remote computer sends a request or initiative by the acquisition system to transfer data to a remote monitoring computer and the Internet for device interconnection.

1.3 network interface chip select

Design uses the Microchip Technology (Microchip Technology, Inc.) launched an independent 28-pin Ethernet controller ENC28J60; with RJ45 connector cable of EIA/568A wiring standard eight-core twisted pair transmission medium used to RJ45 connector for the interface.

Network interface circuit design is based on LPC2132 and ENC28J60 function, timing and logic level, the network interface circuit shown in Figure 4.

1.4 Serial Bus Interface

LP C2132 has two UART serial interface module, can be easily connected with the serial device. Design using UART0 as RS232, RS485 interface, as with UARTI. RS232 is mainly used for system debugging, you can also use RS232 communication with the device. RS485 input and output channels as a gateway.

Figure 4 network interface circuit

1.4.1 RS-232 converter

Design uses SP3232E chip. It can be the input level to the standard TTL level (to MCU), also can convert the input TTL level negative logic level (for PC). The operating circuit shown in Figure 5.

Figure 5 SP3232E Circuit

1.4.2 RS485 interface circuit Sipex Corporation

design uses low-voltage RS485 interface chip SP3481, only a +3.3 V power supply can produce 1.5 V differential output of the pressure required. SP348lE work in half duplex mode, the chip includes a driver and a receiver with 8-pin external components.

Output from the LPC2132 R / D signal directly control the SP3481 chip transmitter / receiver is enabled: R / D signal is "1", the SP3481 effective transmitter chip, receiver disabled, at this time can LPC2132 RS485 bus to send data bytes; R / D signal is "0", the SP3481 chip transmitter disabled, receiver, effective at this time LPC2132 can receive from the RS-485 bus data bytes. Shown in Figure 6. This circuit at any one time in the SP3481 chip "receiver" and "sender" can only have one in working condition.

Figure 6 RS-485 circuit connection

2 Conclusion

With the wide application of electronic technology, intelligent anti-tampering control technology will become a development trend that the proposed use of the gateway and the new sensor on the transformer parameters to be tested. Debugging results show that the high reliability, ease of use, using the above method to establish the anti-tamper wiring system has a simple intelligent system, the system controller stability, high reliability data transmission, in actual use has achieved good results, promotion of a certain significance.

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