The pulse and the blood oxygen degree of saturation had reflected human body’s important physiological condition, the related measuring technique and the measurement equipment obtained the widespread use in clinical, for instance pulse blood oxygen degree of saturation instrumentation. The pulse blood oxygen degree of saturation instrumentation present main application in the operating room, the ICU hospital ward and so on, uses in the seriously injured patient’s life symptom guardianship. Although blood targets and so on oxygen degree of saturation and heart rate in the sports scientific research, the non-bed patient’s guardianship and the special occasion (for example military field) also have the important meaning, but because the present this kind of equipment is the central control, the equipment volume is big, the use not conveniently, the price to be expensive, the manipuility was bad, has limited the related application.
In order to solve these problems, this article introduced based on the wireless territory net (WPAN) design pulse blood oxygen degree of saturation instrumentation. WPAN was for establishes the wireless transmission technology which between the small scope equipment the wireless connection developed, the IEEE standardization association has formulated the IEEE802.15.X standard for this reason. This article involves the transmission technology tallies aims at the low speed WPAN formulation specially IEEE802.15.4(ZigBee) standard.
1 system’s composition and function
Based on WPAN pulse blood oxygen degree of saturation instrumentation’s system structure as shown in Figure 1.
The instrumentation moves gathers the terminal the function: Examines human body’s blood oxygen degree of saturation, the pulse and the pulse intensity, and through WPAN connection module data transfer for examination system master station. The instrumentation moves gathers the terminal to divide into examines the probe head, the blood oxygen degree of saturation monitor module, the power source and parts and so on WPAN connection module. Examines the probe head and the blood oxygen degree of saturation examination module for the outsourcing OEM module, is the American BCI Corporation’s product, it uses the electro-optical law and the Bill theorem, thus realizes not creates the examination. The instrumentation moves gathers the terminal also to support one independent working way, this working suits in continuously the non-real time operation situation.
Instrumentation master station function: Receives through the WPAN connection and saves the instrumentation to move gathers the information which the terminal sends out; According to operator’s instruction on the display monitor demonstrated the mobile termination transmits real-time information or historical data; When the examination parameter surpasses the threshold value sends out the alarm; May according to need through the fast ethernet connection and the backstage support management system management system correspondence, completes the more complex management function. An instrumentation master station may connect many instrumentations to move gathers the terminal, not only increased the use conveniences, moreover raised the master station use factor and reduced system’s use cost. Besides examines the probe head and the blood oxygen degree of saturation examination module, system other parts to independently design completely, below gives to introduce separately.
2 instrumentations move gather the terminal the design with to realize
The instrumentation moves gathers the terminal WPAN connection module the function: After the WPAN connection module receive instrumentation master station’s order, after ordering the analysis through the RS2232 connection to the blood oxygen degree of saturation examination module issues the control command; Receive blood oxygen degree of saturation monitor module gathering data and reaction control information, after pretreatment and pack after WPAN connection module transmission for instrumentation master station.
2.1 instrumentations move gather the terminal connection module hardware design
The instrumentation moves gathers the terminal WPAN connection module hardware composition as shown in Figure 2.
the (1)MCU partial functions and realize
The MCU part is the WPAN connection module core, completes the connection module each constituent the control, the coordinated and the data processing. Concrete function: Through the RS232 connection and the blood oxygen degree of saturation examination module correspondence, realizes to its control and the disposition, and receives the examination data; Realizes through the SPI connection and the status indicator connection to the RF transceiver disposition and the examination, and completes the launch and the receive data exchange; Through the USART connection and the data-carrier storage connection, complete data-carrier storage’s read-write operation; Through the power source examination and the status indicator part, monitors the supply voltage situation, and can have the warning prompt through the status indicator.
the (2)RF transceiver’s function and realizes
The RF transceiver’s function is realizes must transmit data wireless receiving and dispatching. The concrete function includes: Completes through the SPI connection with the MCU part data exchange, the data content including the data which and from the MCU part control and the disposition information must transmit; According to comes from MCU the control and the disposition information adjustment related RF parameter; Will transmit the state feedback through the condition and the instruction connection to give MCU; Completes the data through the antenna the translation and the receive; Completes WPAN the physical level function, realizes the physical level protocol processing. This part uses Chipcon Corporation CC2420 to realize.
(3) data-carrier storage’s function and realizes
Data-carrier storage’s function is the cushion blood oxygen degree of saturation examination module gathering data. Data cushion main application in wireless connection unreliable situation. The data-carrier storage when the wireless connection not unobstructed, is unable completes the gathering data the prompt transmission the cushion agglomeration data, so when the data path restores transmits these data; Data-carrier storage’s another function is when the migration gathers the terminal off-line use saves the gathering data, this suits to monitors the object the long-term non-real-time condition track.
The data-carrier storage uses ATMEL Corporation’s new FLASH chip AT45DB041 to realize. When moves gathers the terminal work when the off-line condition, gathers the data storage in this memory, the data storage sustainable time is bigger than 48h, if uses the compress technique stored datum, the data storage duration is bigger than 168h.
2.2 instrumentations move gather the terminal the software to realize
The instrumentation mobile termination’s software is based on the Webit510 operating system development. Webit510 has the following characteristic: Face 8/16 low cost micro controller; Complete grab type event driven fixed priority scheduler program; Supports 256 priorities, the same priority duty follows the FIFO scheduling strategy; Uses the signal quantity mechanism to realize the synchronization or incompatible sharing; The timer management supports disposable and the periodicity fixed time; Simplification, highly effective dynamic memory management strategy; Flows the device management; Supports the multistage tables of contents the filing systems; Built-in TCP/IP agreement stack; Support movement duty debugging on foot.
Instrumentation mobile termination’s software’s structure as shown in Figure 3.
3 instrumentation master station’s design with realizes
Instrumentation master station major function: Gather the terminal correspondence after the WPAN connection and the migration, realizes to moves gathers the terminal the control, and accepts from the migration gathers the terminal the gathering data; Through monitor module by character either graphic mode demonstration gathering historical data or real-time data; Completes the control or the inquiry order input through the touchscreen by the menu form; Realizes according to the user request to the historical data management and the excavation, the memory gathering historical data and has the historical data automatic clearing and the fixed function; Has the fast ethernet connection, may realize through this connection with the backstage management system management system’s connection.
3.1 instrumentation master station hardware design
Instrumentation master station’s hardware architecture as shown in Figure 4. Below introduces each main part separately the composition and the function.
the (1)CPU part’s function and realizes
The CPU part completes the master station each constituent the control, the coordinated and the data processing. Concrete function: Are connected through the system bus and the memory, complete the correlation data the processing, processing and the memory; Are connected through the LCD connection and the colored liquid-crystal display, realize the information demonstration, realizes the man-machine interaction; Are connected through the touchscreen connection and the touchscreen, realize the control command input; Are connected through the bus interface and the ethernet controller, may the instrumentation turning on back-office support network, realize the system message centralized management and with the backstage management system management system’s fusion; Realizes through the SPI connection and the status indicator connection to the RF transceiver disposition and the examination, and completes the launch and the receive data exchange, realizes with the instrumentation mobile termination correspondence; Through the power source and the peripheral circuit, realize to system’s power supply.
(2) instrumentation master station memory’s function and realizes
Memory’s function is the memory system procedure and the application procedure, the memory migration gathers terminal gathering the historical data and provides the program run the memory space.
(3) fast ethernet connection’s function and realizes
In order to realize with the backstage management system management system’s cooperation, the instrumentation master station provides a fast ethernet connection. Through this connection, may facilitate the master station and the hospital medical record management system management system, the cost system, or other application unit’s backstage service support program’s connection.
(4) man-machine interaction contact surface design
Some experts pointed out: Regarding the user, the man-machine contact surface is the system itself. Therefore the man-machine contact surface holds the important position in the system. In this system, the man-machine contact surface’s hardware part is composed of the colored tablet LCD monitor and the touchscreen, the touchscreen uses in inputting each kind of control/inquiry order and each kind of initial datum, the LCD monitor uses in returning to each kind of order the operating result and demonstrates each kind of monitor data or the monitor curve. The monitor uses SHARP Corporation’s LQ035Q7DB02[10] to realize, this screen to have necessary touchscreen colored LCD.
(5)WPAN connection
The WPAN connection realizes the instrumentation mobile termination and the instrumentation master station correspondence, with instrumentation mobile termination RF transceiver part basic same.
3.2 instrumentation master station’s software realizes
The instrumentation master station’s software is based on the ARMLinux development. Since the late-1980s, presented some embedded operating system one after another, but its soaring price makes one shrink back at the sight, and source code’s closeness greatly has also limited exploiter’s enthusiasm. Therefore, unifies the domestic and foreign special details, chose the ARMLinux operating system achievement to develop the platform. Instrumentation master station’s software architecture as shown in Figure 5.
The ARMLinux essence is mainly composed of 5 subsystems: The process dispatching, the memory management, the virtual file system, the network interface and the advancement correspond. Process dispatching control advancement visit to CPU; The memory management allows many advancements to share the main memory region safely; The virtual file system hid each kind of hardware’s nuts and bolts, has provided the unified connection for all equipment; The network interface has provided to each kind of network standard deposit and each kind of network hardware’s support; Advancement communication (IPC) support advancement each kind of correspondence mechanism.
The demonstration processing module and the touchscreen processing module complete the man-machine interaction together. The demonstration processing module completes the gathering data the graph or character display, and according to user operation demonstration all levels of menus; The touchscreen processing module and the demonstration processing module coordination completes each kind of control or the command information input.
The embedded database realizes operations and so on historical data management, inquiry and maintenance.
4 realize the result
Has developed based on the WPAN blood oxygen degree of saturation instrumentation’s prototype successful and through the test.
The test result is as follows: Various parameters’ measuring accuracy with the blood oxygen degree of saturation monitor module which chooses is completely same; An instrumentation master station are most may simultaneously move with 64 instrumentations gathers the terminal correspondence, and guaranteed that transmits accuracy which and timeliness and demonstrated; The wireless transmission speed is 250kb/s; The wireless transmitting range may reach 75m (to be able to change according to exploitation conditions change).
The test result indicated that the instrumentation has achieved the anticipated design target completely, has the broad market prospect.
5 conclusions
Based on the WPAN blood oxygen degree of saturation instrumentation’s development, expanded equipment’s applicable scope greatly, in aspects and so on equipment’s usability, conveniences, manipuility and applicable scope had the enormous enhancement; Because a master station may connect many migrations to gather the terminal, reduced the use cost greatly.
