Design And Implementation Of Processing And Displaying Module Of The Handheld ECG Device

The modern electrocardiograph covers ICU, prevention, diagnoses and other conventional fields, which are mainly divided into ECG bedside monitoring system and the Holter. But their cubage, weight, power and cost couldn't meet requirements in some occasions.In this paper, we present a handled ECG device, which is low-power, low-cost and has the whole basic functions of a typical ECG device. It has three functional modules, which are main control, sample and distance transmission and data processing and display. We used C8051F320, C8051F330 and EP7312 to realize the three modules, and connected them through UART.The emphasis of this paper is the software and hardware design and realization of data processing and display of the device. We utilize EP7312 in this module, which is an embedded CPU belonged to the series of ARM7TDMI and has a stronger calculation capability. And EP7312 integrates the controllers of on-chip SDRAM, UART and LCD, provides the interface of FLASH. All of these guaranteed performances of system.We designing the system boot codes referred to the open source of Bootloader. The main routine is referred preemptive and foreground/background task scheduled, and guarantee the real-time requirement. The ISR (interrupt service routine) receives and decides the data from main control module, then execute the preemptive task schedule if the data is commander. And if ECG, will be stored it in buffer which shared by ISR and filtering process. The filtering process and the display process are executed in the main routine; ECG will be displayed on LCD after filtering.Theoretical foundation of filtering arithmetic is wavelet analysis; method of filtering is the Modulus Maxima. According to the test, we can conclude that the best filtering result is wave component under level-2 decomposition, and filtered waves could be clearly displayed on the LCD after transplant of filtering arithmetic. The efficiency of arithmetic is guaranteed by the Mallat transformation; and it is proved that the hole system could be achieved our objective that ECG could be real-time filtered and displayed.