Reconfigurability in Embedded Systems using SunSPOT Technology

Easy run-time reconfigurability is a very desirable quality in many wireless sensor applications. In our project we show how a reconfigurable embedded sensor node, SunSPOT, can significantly extend its set of capabilities through run-time reconfiguration. We illustrate this using a portable electrocardiogram application whose job is to track the EKG patterns in patients and detect any potential problems. Since a set of possible anomalies is much larger than the size of available storage on the node, our design starts out with a subset of algorithms capable of detecting the most likely problems. As the EKG is being analyzed, the device can then reconfigure itself as necessary to be able to detect all different types of heart conditions at very low cost. Overview This project implements an EKG on a reconfigurable, embedded platform, the SunSPOT, made by Sun Microsystems. It is able to read in waveforms from the heart and display it on a web browser for people to see and doctors to analyze (see Figure 1). Figure 1: EKG heart waveform Current methods of EKG health monitoring involve having patients visit their doctors where they will then be monitored for a short period of time. However, such monitoring can not accurately asses the complete health of the patient, nor is it able to predict infrequent occurrences of abnormalities. This project aims to monitor the health of patients as they live their normal, daily lives through the use of a portable EKG device that can detect anomalous heart behavior. However, since the device is portable, there are memory constraints which can limit us on the thoroughness of our health detection applications. To bypass this, we developed a set of small, yet effective algorithms which can each individually be wirelessly transmitted onto our EKG device and updated as necessary. For instance, when the device comes across a scenario that it is unfamiliar with, it will reconfigure itself in order to better analyze the situation. Our devices can be used to sample, process, and transmit data and results from the patient to the hospital in real-time via a wireless connection for computers or doctors to analyze and determine if there is a life-threatening situation such as an upcoming heart attack. This can be used as a measure to closely monitor a patient to catch irregular and uncommon medical problems as he lives his daily life. Motivation The motivation behind this project is that this device is reconfigurable, low power, easily programmable, and very easy for hardware integration. As an embedded system that is reconfigurable, its benefits are that the device can be reprogrammed wirelessly. Previous methods of reprogramming embedded devices require the use of a physical cable connection which means physically going to the device and connecting a cable to it. However, now that reconfiguration is wireless, we can exploit that capability by writing code that can be updated and modified via wireless technology. As a low power device, it is able to run for extended periods of time which allows for extensive heart monitoring without replacing or recharging batteries. Using Java as the language to program the device means that the designer has access to an extensive set of libraries for quick and easy programming. Also, the device has its own class-based hardware API written in the Java language for easy hardware integration. Hardware Architecture Our EKG monitoring device consists of three main parts: the amplifier, the multiplexing circuit, and the SunSPOT. The amplifier amplifies the signals from the body. The multiplexing circuit determines which signals from the body should go to the amplifier and the SunSPOT has an ADC on it to sample the analog signals and convert them to digital signals for processing. Figure 2 is an overview of the whole hardware architecture. Figure 2: Overview of hardware architecture