Study On Data Acquisition System For ECG Signal Based On ARM Architecture

Electrocardiograph monitor (ECG monitor) is an important accessorial diagnostic implement of modern clinical iatrology. On monitoring the patient who has heart disease or other serious illness, it can provide important reference to diagnose, analyze, treat and research the illness. ECG data acquisition system is the necessary channel to acquire ECG signal from the surface of the body to computer (including all kinds of processors). It will directly effect the signal processing followed. Since the ECG signal will be disturbed by electromagnetic interference and circuit noise, it is important for the ECG data acquisition system to reject these interference and noise and increase signal integrity. This paper does some research in this field. ARM is the embedded microprocessor, which emerged in the 90s of last century. With the development of ARM architecture by the corp. of ARM, and many companies, such as Atmel, Intel, SAMSUNG and PHILIP, buy the patents of ARM and manufacture millions of imbedded microprocessors with the core of ARM inside. Now, ARM has been the dominant member in the embedded microprocessor families, it occupy a great quotient in the low-end and high-end embedded production. There are embedded productions based on ARM architecture everywhere. I believe that ARM will be compelling in the 21st century. This paper advance the way of applying the high-end embedded microprocessor chip of AT91RM9200 into the ECG monitor, and design the ECG data acquisition system based on ARM architecture. At the first of this paper, the significance of this subject study is discussed. At the same time, the history and situation of the ECG monitor, the types and the characteristic of modern ECG monitor are summarized. And then, the key technologies, embedded technology and data acquisition technology are introduced. The basic conception and the characteristic of embedded system, the operating system of embedded system, the microprocessors of embedded system, ARM microprocessors and the application fields of modern embedded system, the characteristic and the constituents of modern data acquisition system, the measuring technology of weak signal are systematically expounded. The characteristic waves and the intervals of the ECG signal are analyzed from the viewpoint of Physiology and Electrophysiology, followed with the interference and noise in the ECG signal and the methods to reduce them. In the chapter 3, ARM architecture is deeply studied. The types of embedded microprocessor are summarized at first, with the types and productions of ARM microprocessor. Then the chip of AT91RM9200 is introduced, including the core of the microprocessor, the mode of the processor, registers, memory system, the mode of addressing and interrupt. At the last part of this chapter the mode of developing the embedded system is involved. Designing and developing hardware platform is the most important work in this paper.The whole circuit design is partitioned into two main parts—acquisition circuit and processing circuit, and is discussed in the later two chapters. The acquisition circuit includes the circuit of front amplifier and right driver, the circuit of the main amplifier and filter(involved with highpass filter , two order lowpass filter and double 'T'band stop filter), the circuit of elevating voltage and overvoltage protection, the circuit of data conversion, PCB design and circuits debugging.The design of processing circuit includes the circuit of power management, the circuit of AT91RM9200, the circuit of memories, the interface circuit of Ethernet, the interface circuit of LCD, the USB interface circuit of keyboard and mouse. Designing and transplanting the embedded software and the hardware platform are inalienable, they constitute the embedded system corporately. The software of embedded system with embedded operating system includes bootloader, embedded operating system, file system and application. How to develop and transplant the software above will solved in the chapter 6. We did experiments in the hospital of Chongqing University, and the result was as good as I expected. In the last chapter, the pictures of experimental locale are placed, the discussion about the result is given, and the research of next step is advanced.