Design And Implementation Of Portable Ecg Device Based On Stm32

At present, the rate of cardiovascular disease and the related hazard factor in our country have increased. ECG is an important method of diagnosing heart disease. However, conventional ECG devices have limitations of a big size and bulky volume and not easy to carry. It is not convenient for patients to stay in the hospital for long, so it becomes very important to develop a portable ECG monitor.The project proposed a plan of ECG acquisition, analysis and processing system which based on STM32, and completed its hardware and software design. The core of the system is ECG acquisition circuit, which is to complete the signal extraction. The function of the ECG signal processing circuit is to complete the A/D acquisition, displaying, filtering and storage of the signal.The system is a typical biomedical signal collecting-processing one, which processes weak signals in strong noise background. Because of the impact of noise and interference, the front-end acquisition circuit needs to have higher performance. According to the characteristics of ECG, the precision instrumentation amplifiers are chosen to design the preamplifier circuit. In order to reduce the interference effects, right leg drive circuits, high- pass filter and low-pass filter is designed to extract the ECG signal. Through the A / D converter of ECG processing circuit, analog signals are converted into digital signals, which are sent to the microprocessor for further processing. ECG processing circuit, core of which is a microcontroller of low cost and low power Cortex-M3 by ST, mainly include power management circuits, STM32 processor circuits, SD card storage circuits, serial communication circuits, LCD interface circuits and so on.The software design used C language to program and completed ECG collection, filtering, display, storage and communication. The development tool is IAR Embedded Workbench for ARM. The main program completed a variety of specific functions by calling the subroutine modules. Subroutines included system initialization, ADC, digital filtering, waveform displaying, data storage, serial communication and so on. This system validated the ECG algorithms using ECG data from MIT-BIH ECG database by MATLAB, and at last suppressed noise and interference effectively by using a simple integer coefficient filter design method. Besides, the system can also communicate with the host computer by RS232 serial port, so PC can further process the uploaded data using its powerful data processing and analysis capabilities. Host machine management software implemented a low-cost ECG signal acquisition system using VC++6.0 software development platform. The management software is to realize the functions of data acquisition, processing, display, storage and analysis. The subject realized the desired target, including designing the system's hardware and software, and making a prototype machine. The system was proved running well, and could meet the design requirements.