A Design Of Portable ECG Monitor Based On Smartphone

ECG diagnosis is still the important measure of cardiovascular disease's prevention and treatment.The electrocardiographs and monitors are becoming miniaturized and multifunctional with the development of electronics industry.IoT(Internet of things)rapidly rises accompanied by wireless technology,meanwhile,wearable smart devices have gained the recognition of consumers,and they are very potential.In this paper,a design of portable ECG monitoring system based on smartphone is proposed,which combined with electrocardiograph's professional,comprehensive characteristic in data measurement and wearable device's compact,flexible feature.It can be used for monitoring the long-term ECG information of patients with cardiovascular disease,and also daily care of ordinary people.This system lays the foundation for the development of m-health(Medic Mobile).First of all,this thesis introduces ECG signal in brief,and notes that the ECG contains many physiological parameters with diagnostic significance.Then,the thesis explains the principles and meaning of the processing circuit step by step according to the characteristics of the ECG signal and the noise environment around it.After that,the thesis proposes the integrated chip ADS1293 applied to the system,helping to reduce noise coupling from the outside world,but also more in line with the design requirements of wearable devices for small volume.Taking the double-lead acquisition mode for example,the peripheral circuit and power management solution are designed,the configuration of chip's corresponding registers is completed,operations of SPI communication and methods of reading the ECG data correctly are accomplished.The next,the thesis introduces the rise of Bluetooth 4.0 and the BLE(Bluetooth Low Energy)protocol.It proposes a design of Bluetooth communication module.In hardware design,it introduces the outstanding characteristics of Bluetooth chip CC2564 and its basic principle,but also provides RF antenna options.In software design,taking Bluetooth communication module as master device,initialization of the Bluetooth connection with slave device is completed.Then,callback function examples of sleep,timer interrupt and instruction triggers have been taken.Moreover,the thesis proposes a method for reducing the power consumption of the MCU and a way for data verification which fitting the Bluetooth communication.Once more,aiming to extract R wave of ECG,the thesis introduces the process of filtering,differential,square and moving window integration in order to obtain a period detection signal of single peak.In the afterwards R-wave detection process,it points out that extracting R-wave from abnormal ECG data with a single threshold detection method,there is a high rate of false detecting.So the dual-threshold detection menthod whose threshold values are variable is presented.It is proved that dualthreshold detection method is more reliable by comparing the accuracy of detection results with these two methods.Eventually,this thesis briefly describes the construction of the Android operating system.With the serial debugging assistant on PC(Personal Computer),it elaborates the process of Bluetooth connection step by step when smartphone behaves as a slave device.In the end,a design of Application interface,classes of data processing and algorithms,and a solution of display with mitigating the block in main thread are presented.Innovation point:(1)ECG acquisition circuit uses integrated chip ADS1293 to replace the traditional analog circuit,and that will make products smaller and more wearable;it's more reliable for products that the integrated chip helps ruducing the external electromagnetic noise coupling on the circuit;products will also become more flexible by configuring the registers to change lead connection.(2)Applying the BLE mode of Bluetooth 4.0 in Bluetooth communication module helps expand battery life and makes products more efficient and stable.(3)Instead of embedding the interactive screen into a circuit,smartphone is used for Terminal display.It not only reduces the hardware cost of products,but also promises products have a broader development.This design contributes to the establishment of a medical monitoring system which has smartphone as a control terminal with a plurality of modules accompanied,lays the foundation for the development of m-health.