Summary: Describes the AT91SAM7S64 microcontroller main features and performance, an analysis of the use of the chip to reduce and optimize peripheral circuits, to improve precision, real-time and reliability advantages.
Highlights the chip for IR control, automatic camera software and hardware design, analysis and real-time performance for increase in hardware design.With the social and economic development, increasing people's living standards.
How to protect the property of a community focus. Although various alarm device Yong people market, but there are many features, technology is not mature, less effective against theft. Infra-red alarm system is the application of the broader one alarm technology, through intelligent control MCU, greatly improving the efficiency of the intrusion. Microcomputer control infra-red alarm system it works is the use of infrared sensors for detecting anti-area volunteers move radiation infrared heat energy, dedicated infrared sensor processing IC to receive signal processing, delivered to the single-chip controller, intelligent control MCU, start taking your camera. The system features as long as the warning zone space, or non-open hours to detect illegal activities on the human body, you can immediately start automatic alarm system. The alarm device has a low false alarm rate, strong anti-interference ability, comes with a variety of functional use, safe and reliable, easy installation, suitable for families, offices, shopping centres, street storefront, micro-car, garage, warehouse, etc. Infra-red alarm system and video capture cards such as compared to traditional image acquisition systems, embed image acquisition system is of small size, low cost, high reliability, in intelligent transport, long-distance monitor, computer vision application wide areas. This article describes the design of embedded image acquisition system is adopted to the ARM7 core AT91SAM7S64-AI as master chip that controls the CMOS sensor OV6620 for image acquisition, and control by AT91SAM7S64-AI first image data stored in the final will AT45DB041D image acquisition results in a variety of communication interface to transmit the image acquisition system with only one ARM chip enables OV6620 feature control, timing synchronization, data acquisition and processing, and other functions, the system structure is compact, powerful.1 the characteristics of the AT91SAM7S64
Atmel AT91SAM7S64 is 32-bit single-chip company, with high performance, low power, full-speed USB2.0 interface and a rich peripheral interface resources, etc., is connected to PC, mobile phones, and other peripheral vision chip.
AT91SAM7S64 microcontroller using Nava technology industry on low power design requirements. The voltage range is 2.0 5.0 v. When the frequency is 32 kHz, voltage 2.0 V, current typical 8.5 A, when the frequency of 1 MHz, voltage 2.0 V, A typical value is 100. When voltage 2.0 V, watchdog timer current typical value 1 A [1-2].2 hardware
Image acquisition and alarm system consists of an infrared alarm circuits, power supply circuit, USB interface circuitry, OV6620 image sensor acquisition circuits, CPU, CPU external interface circuit EEPROM, circuit, as shown in Figure 1.
2.1 processor
The system processor with Atmel company AT91SAMS64 chip, and other series MCU circuits compared to their external circuitry.
Alarm system, and on the position machine communication completed by USB, the processor integrates USB device port, making it the ideal on-chip peripherals such as PC and mobile phone, etc. In addition the image acquisition and need to transfer large amounts of data, AT91SAM7S64 64 KB high speed Flash and 16 KB of SRAM, but OV6620 image sensor and continuous capture image data taken from the clear space is not sufficient, so the need for external memory for data storage. Infrared sensor in the collection to an infrared sensor signal after the infrared sensor processors processing, output signal, the signal from 0 v to 3.3 V voltage jump can be directly connected to the CPU, AT91SAM7S64 through universal input output port receives a signal the hopping, I2C and image sensor OV6620 communications, gets the image to the image through 8 parallel interface back to the CPU, and stored in an external storage.2.2 infrared signal processing
Infrared signal processing part adopts BISS0001 infrared signal sensing processor, which is the operational amplifier, voltage comparator, and the State controller, delay timers, embargo time timer and voltage reference, and other components of mixed-signal ASIC.
It can be widely used in a variety of sensors and delay controller. BISS0001 leverage operational amplifier OP1 composition sensor signal conditioning circuits, signal amplification. Then coupled to the operational amplifier OP2, then the second level of magnification, DC-elevation for VM (≈ 0.5 VDD) is sent to a comparer COP1 and COP2 and amplitude of bi-directional, check out effective trigger signal Vs. Because VH ≈ 0.7 VDD VDD, VL ≈ 0.3, so when VDD = 5 V, may be effective in suppressing the noise of ±1 V interference and improve system reliability [3]. In the infrared alarm circuit, infrared sensor receives the signal after BISS0001 processed by BISS0001 pins 2 output, in this chip measurement because signals output its PIN 3.3 V can be connected directly to the pin of the CPU. Infrared signal sensing circuit whose circuit the design as shown in Figure 2.2.3 image sensor
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