基于单总线及无线通信技术的医院体温监测报警.doc

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1、基于单总线及无线通信技术的医院体温监测报警系统基于单总线及无线通信技术的医院体温监测报警系统摘要体温测量在临床诊断和治疗方面具有非常重要的意义。由于传统的人工测量方式有许多缺点，如测量时间长，测量精度低等等，这就是很难自动，准确地实时监控病人体温的原因。针对这一问题，介绍一种分布式体温监控系统。多个温度传感器DS18B20的连接，实现了人体温度信号的采集。单片机AT89C52处理测量信号和驱动字段的显示和报警设备的工作。系统通过NRF905的无线收发芯片，完成信号从分站无线传输到中心站的工作，并且通过PDIUSBD12的USB适配器与上位机连接，这就是病人体温分布式集中监控系统。我们的实验表明

2、，系统的无线通信较好而且温度测量误差小于 0.1C，完全符合临床医学要求。由于系统采用了模块化设计，可以应用到其他领域，如温室环境智能监控等。关键词：温度监控，无线遥控器，NRF905，单片机AT89C52，LABVIEW I.简介目前，在大多数医院，病人的生理参数采用定时人工测量的方式。例如，护士每天去病房，给病人测量体温，做好记录并绘制体温变化图，作为医生诊断疾病的参考资料。这种传统方式不仅浪费护士大量的体力，而且汇总和查询分析测量结果繁杂，以及当患者出现特殊情况时不能及时反馈，从而导致延误治疗时间。通过分析，我们可以看到这种方式有很大的局限性，特别是与患有传染性疾病的患者，监测人员是不便

3、接触的。所以，针对这个问题，我们运用传感器和单片机微处理器等技术，在医院设计了一个体温监测和报警系统。系统采用单总线温度传感器DS18B20和湿度传感器HS1101，通过无线通信技术和USB通信接口的设计，弥补了传统系统的缺点。我们通过监控室里的计算机对每个病房里的病人的体温进行实时监测，可以提高工作效率，并在节约医疗资源方面起到积极作用 。II.系统结构和工作原理分布式智能医疗体温监测系统由中心站和许多监控终端组成，包括电源，温度信号采集，射频发射和接收，显示，报警，通讯模块等。系统通过单片机AT89C52的核心控制和运作NRF905。在工作时，主机根据需要传输地址信息的射频信号，通讯地址终

4、端接收信号并向主机传输数据，主机接收数据进行分析处理并上传到计算机。 系统实时完成每个病房患者体温的监测，收集和数据处理。普通的计算机采用USB适配器PDIUSBD12，使上位机的USB具有接口通信功能。系统以单片机AT89C52作为监测节点控制器，通过USB接口使上位机与工作中心站连接，并实现信息的交换。计算机负责整个系统的监控管理。工作中心站控制器接收上位机的各种操作控制命令和设置参数，每个现场监控终端的数据采集器实时接收和显示温度值，并控制现场的报警开关。上位机通过分析和处理接收的数据也可以实现显示和报警。 III.系统的硬件设计系统硬件主要包括两部分：现场监测终端站和中央电脑监控室（工

5、作中心站和上位机）。从站的工作是用LED显示患者的体温，并实现限温报警，以及通过控制NRF905的芯片完成信息传输。监控室以AT89C52单片机作为核心控制器，实现处理器的数据接收和温度控制模式的下载，并通过USB适配器PDIUSBD12的通信模块完成与上位机的连接，可实现每个病人的体温显示和限温报警。 A.温度监测电路 我们选用美国的Dallas公司生产的单总线数字温度传感器DS18B20作为温度传感器。它提供9位二进制温度信息，温度的测量范围为-55+125，测温精度为0.0625 C。因此，它可以准确地完成任务。DS18B20有三个引脚VCC，GND和数据端。其中，引脚VCC为电源接口，

6、GND为接地，数据输入/输出端是用来传输温度数据的。DS18B20只有一个信号线和接地线连接至单片机。DS18B20由数据线完成读、写数据和温度值的转换。温度转换时间短，最大转换时间是750ms，并能设置温度报警上下限值。当温度超过限定值时，报警信号启动。由于系统需要在不同的地方设置温度传感器，所以我们采用外接电源的方式。由于DS18B20具有唯一的ID，从原理上来说，我们就可以将所有传感器挂接到一条总线上，但由于AT89C52单片机总线驱动能力和总线分布电容的限制，一个I/O端口进行发送或接收的能力是有限的，只有8个芯片可以连接。因此，为了改善总线驱动能力，我们可以连结上拉电阻和9013，这

7、可以保证在I/O口输出4.7V的高电平。系统用P2.0口作为发射端，P2.1口作为接收端，可实现读写分离。而且可以连接几十个DS18B20芯片，传输距离达到50米，并消除信号干扰问题。 单片机AT89C52的P2.0和P2.1端口控制所有DS18B20收集的温度值。我们还可以通过其他I/O端口对病房或监测的病人收集多组数据。此外，为了减少总线分布电容的影响，我们选择STP总线作为单总线电缆。 B.体温显示 温度信号由AT89C52单片机处理后用LED显示，可告知医务人员和患者。系统采用74HC4511作为LED数码显示驱动电路的核心芯片。74HC4511是一种高度集成的串行输入/输出共阴极LE

8、D显示驱动器，可驱动8位7段数码管。它有三根线与单片机连接，可以实现8位LED数码管显示控制和驱动。工作寄存器可以设置指令，使74HC4511进入不同的工作状态。 C.语音报警电路 为了防止系统断电和温度或湿度控制异常，我们设计了现场语音报警电路。我们采用美国ISD公司的具有语音记录和回放功能的语音芯片ISD1420完成语音报警和提示。该芯片具有64K/128K EEPROM且静态工作时的电流只有0.5A，并且记录时间达到20s，可划分成160个短脉冲，每个脉冲25ms。可以进行连续重复记录和分段纪录。 通过分段录制和播放，可以发出不同的报警通知。当REC引脚接低电平时，可实现录音功能，当引脚

9、PLAYE或PLAYL接低电平时，可进行播放。如果A6或A7任一脚接低电平时，所有的输入地址作为当前记录或回放的起始地址。当PLAYE、PLAYL或REC处于下降沿时输入地址被锁存。SP +和 SP-连接扬声器，实现语音报警。 D.无线收发模块接口 系统选择北欧集成电路有限公司的射频收发器NRF905芯片。工作电压为1.93.6V，32引脚和QFN封装（55毫米），工作在国际开放的ISM 433/868/915MHz三个通道，传送时间不到650us。采用GFSK调制类型，速率达到100kbps。NRF905是由频率合成器，接收解调器，功率放大器，晶体振荡器和调制解调器等组成，无需连接过滤器。它

10、的最大发射功率为+10dBm时，最大传输距离可达1000米，并具有高抗干扰GFSK调制，速率为100kbps。其内部具有通信协议和CRC，采用SPI通信完成所有的无线收发器，且耗电量非常低，- 10dBm输出功率的电流只有为11mA，接收模块的电流为2.5mA，自由模式或关闭模式的电流是2.5mA，它易于实现低功耗的设计。此外，PCB天线的设计，可以提高系统的稳定性。E.USB接口电路 USB接口是连接PC机与工作中心站的模块。一个端口连接显示控制器的USB接口，其他的连接工作中心站。由于USB协议是相当复杂，我们使用USB控制芯片来避免这个麻烦。USB1.1接口的传输速度峰值可以达到12Mb

11、/s。因此，本系统选用USB1.1标准，整个模块由USB控制器和单片机等组成。 USB控制器是USB总线接口电路的核心。该系统选择飞利浦公司生产的PDIUSBD12芯片，用并行总线优化USB组件，能够满足USB1.1和DMA通信的要求。通常，在基于微处理器系统中它通过告知并行串口进行通信。在批量传输模式下，采用8位并行数据口的传输速度可以达到1Mb/s。AT89C52使用，ALE，和P0端口对PDIUSBD12采用地址/数据总线监视系统模式。PDIUSBD12在AT89C52单片机处于下降沿时输出地址。在这种模式下， AT89C52单片机使用MOVX指令传送数据，传送指令时若输出地址为奇数时，

12、数据取反后再传送到PDIUSBD12。 IV.系统软件设计系统软件设计采用模块化程序结构，终端控制器软件设计采用KEIL C51语言，上位机控制软件采用LABVIEW和ACCESS来设计。系统软件主要由上位机通信软件，现场监控节点温度的采集，处理和控制算法软件等组成，软件系统采用模块化设计，划分为一些相对独立的功能模块，并安排适当的进入和退出端口参数。 在系统设计中，为了避免通信干扰，不同病床的病人终端控制器和监控温度传感器工作在不同频率段，每个病房子控制器的温度监测都会发送地址码，方便知道是哪个传感器发送温度。地址码有两种方式：协议寻址和非协议寻址。非寻址使用NRF905的射频配置寄存器，发

13、送地址到地址寄存器，因此，分站可以决定哪个监测温度传感器传输数据。协议寻址包括分站的地址和温度监测数据传输地址。因此，分控制器可以判断哪个传感器在传输数据。NRF905收发器的物理地址采用其默认地址0xE7E7E7E7，这个系统采用协议寻址方式，子控制器和温度传感器分别定义了监测温度传感器的通信帧格式。每个子控制器只有一个地址，且长度只有一个字节。监测温度传感器的地址长度是两个字节。命令指令是一个字节。当命令地址为0x55时，分控制器通知该监测温度传感器收集数据并上传。 为了使不同的病房相对独立，每个子控制器具有唯一的地址，它的长度是一个字节，监测温度传感器的地址是两个字节，温度数据也是两个字

14、节。 A.启动温度转换功能 B.读温度值的函数 C.温度监控软件传输 单片机下位机的软件是用C语言设计，它主要实现了数据采集，NRF905无线数据的发送和接收等，可划分为若干模块：自检模块，无线收发模块和体温监测模块等。 D.上位机监控上位机软件主要实现基于虚拟仪器的软件LABVIEW8.5的通信，LABSQL Server数据库访问和数据监控等。我们采用G语言软件程序设计框架，并设置通讯数据的采集与传输，以及使用LABVIEW软件强大的图形显示功能设计前面板示范接口，可大大提高人机交互功能。 V.实验及结论对于监视系统的准确性和可靠性，我们使用水银温度计测量一些病人的体温，与本系统测量温度值

15、进行比较，并在同一时间点取值。 通过实验，测量误差的绝对值小于0.1C，与临床医学体温监测相吻合。该系统采用数字温度监测网络，采用无线通信，使每个病人的体温与中央电脑连接，并通过USB接口与上位机的工作中心站连接，克服了传统的电缆铺设的缺点，缩短和简化了电缆布局，并节省了修复成本。系统的准确性和精确度是通过实验证明的，系统硬件具有样本结构，高测量精度，方便扩展，易于实现多点监控，远程监控和沟通等诸多优点。该系统加入各种监测传感器就可实现其它临床检测功能。6Body Temperature Monitor and Alarm System Used in Hospital Based on 1-

16、wire and Wireless Communication TechnologyBody Temperature Monitor and Alarm System Used in Hospital Based on 1-wire and Wireless Communication TechnologyAbstractBody temperature measurement has very important meaning in clinic diagnosis and treatment. Due to traditional artificial measurement style

17、 has many disadvantages such as long measurement time, and low measurement precision, etc, which is hard to automatically and accurately monitor patient body temperature in real time. Aiming to this problem, paper introduces a kind of body temperature distributed monitor system. Multi-temperature se

18、nsors DS18B20 were connected to realize body temperature signal collection, SCM AT89C52 processes measurement signal and drives field display and alarming equipment work. By NRF905 wireless transceiver chip, system completes signal wireless transmission from work slave station to work central statio

19、n, and connects upper PC through USB adapter PDIUSBD12, which the distributed clinic patient body temperature concentration monitor system is carried out. Our experiments show that system wireless communication is better, and temperature measure error is less than 0.1C, which matches clinic medical

20、requirement well. Due to system adopts modularization design, which can be transplant into other field, such as greenhouse environment intelligent monitor, etc.Keywords: temperature monitor; wireless remote; NRF905; SCM AT89C52; LABVIEW. INTRODUCTIONAt present, patient physiological parameter adopts

21、 timing artificial measurement style at most hospital. For example, nurse goes to ward and measures patients body temperature every day, manual records and draws body temperature changing figure, which can be analyzed by doctors as reference of disease diagnosis. This term of conventional not only w

22、astes nurses massive manpower, but also aggregation, query analysis to measurement result is miscellaneous, as well as cannot feedback in time when patient appears special condition, which can cause delay of treatment time. Through analysis we can see, this kind of style has bigger limitation, espec

23、ially, to those patients with infectious diseases, monitoring personnel is inconvenience to contact. So, aiming to this problem, by sensor technology, single chip microprocessor technology, etc, we design a kind of body temperature monitor and alarm system used in hospital. System uses 1-wire bus te

24、mperature sensor DS18B20 and humidity sensor HS1101, by wireless communication and USB communication interface technology to design, which makes up tradition system shortcoming. Through monitoring each wards sub-node of patients body temperature in real time by computer of monitoring room, we can in

25、crease work efficiency, and has active function in saving medical source, etc.II.SYSTEM STRUCTURE AND WORK PRINCIPLEDistributed medical intelligent body temperature monitoring system is composed of central station and many monitoring terminal, which includes power supply, temperature signal collecti

26、on, RF，transmitting and receiving, displaying, alarming, and communication module, etc. System controls and operates NRF905 by core of SCM AT89C52. During working, host transmits RF signal with address information according to need. Corresponding address end machine receives signal and transmits dat

27、a to host, host analyzes and processes receiving data and upload to PC.System completes each ward patient body temperature monitor in real time, and processes collection data. Computer adopts normal PC, uses USB adapter PDIUSBD12, which makes upper PC have USB interface communication function. Syste

28、m uses SCM AT89C52 as monitoring node controller; upper PC connects work central station by USB adapter, and realizes information exchanging. PC is responsibility to whole system monitoring management. Work central station controller receives upper PC various operation control command and setting pa

29、rameters, each field monitor terminal data collection controller collects and display monitor temperature value in real time, as well as controls field alarming switch state. Upper PC can also realize displaying and alarming through analyzing and processing receiving data.III.SYSTEM HARDWARE DESIGNS

30、ystem hardware mainly includes two parts. Field monitoring terminal work slave station and monitor room central PC (work central station and upper PC). Work slave station displays body temperature of patients by LED, and realizes alarming out of limit temperature, as well as completes communication

31、transmission by controlling NRF905 chip. Monitor room. AT89C52 acts as central computer core controller, and realize temperature processor data receiver and control schema download, as well as completes work central station links with upper PC through USB adapter PDIUSBD12 communication module, whic

32、h can realize each patient body temperature display and alarm out of limiting value.A. Temperature monitor circuitWe select DS18B20 as temperature sensor, which is 1-wire digital temperature sensor made in Americans Dallas Co. It offers binary 9 digit temperature information, and measures temperatur

33、e 55C +125C, and has 0.0625C measurement precision. So, it can complete task accurately. DS18B20 has three pins, VCC, GND, and DATA. Among them, pin VCC is power supply port, GND is earth port, and pin DATA is data route port, which is used to transmit dictate and temperature data. It only has one s

34、ignal line and earth line from SCM to DS18B20. DS18B20 completes read, write and power of temperature exchange is offered by data line itself. Temperature transfer time is shorter; maxim transfer time is 750ms，and can set temperature beyond alarm up and down limited value. When temperature is beyond

35、 limited value, alarming signal is start. Because the system needs distance different location set temperature sensor, so we complete it though outer power supply style. Temperature monitor circuit principle diagram is shown as Figure 2.Because DS18B20 has unique series ID, from its principle to say

36、, we can connect all sensor along one wire, but due to limited by AT89C52 SCM bus driving ability and bus distributed capacity, one I/O port carries transmitting or receiving, there is only 8 chip can be connected. So, in order to improve bus driving ability, we can link pull-up resistor and 9013, w

37、hich can assure I/O port output high level in 4.7V. System lets P2.0 port as transmitting, P2.1 port acts as receiving, which can realize read and write divided, and connecting DS18B20 number can reach several ten chips, transmission distance of 50 m, as well as eliminates signal competition problem

38、.SCM AT89C52 P2.0 and P2.1 ports control to collect a group of DS18B20 value. And we can realize multi-groups data collection by other I/O port according to ward or monitoring patients. In addition, to reduce bus distributed capacitance affection, we select STP cable as 1-wire bus cable.B. Body temp

39、erature displayTemperature signal will be displayed by LED after AT89C52 processing, which can inform medical staff and patients. System uses 74HC4511 as LED digital display driver circuit core chip. 74HC4511 is a kind of high integration serial input/output common cathode LED display driver, which

40、can drive 8 bit 7 segment digital tubes with decimal point. It can connect with SCM in three lines, which can realize 8 bit LED digital tube display controlling and driving. Work register can be set by instruction, and makes 74HC4511 enter different work state. C. Speech alarming circuitTo prevent s

41、ystem losing power, and temperature or humidity controlling abnormal, we design field speech alarming circuit. We adopts AMERICA ISD .CO integration speech chip ISD1420 to complete speech alarming and notice function, which integrates speech record and playback. It has 64K/128K EEPROM, and statics w

42、ork currency is only 0.5A, and record time reaches 20s, which can be divided into 160 short bursts, every bursts has 25ms. It can carry out continuous recode, and also subsection record. Through subsection record and play, it can give off different alarming notice. When pin of REC is low electric le

43、vel, it can realize record function, and pin of PLAYE or PLAYL is low electric level, it can realize play. If anyone of A7 or A6 is low electric level, all input address acts as initial address of present record or playback. Address input is latched when pins of PLAYE, PLAYL, or REC in fall edge. SP

44、+ and SP- connect speaker which speech alarm is realized. D. Wireless transceiver module interfaceSystem selects RF transceiver NRF905; NRF905 is Nordic VLSI .co chip. Work voltage is 1.93.6V, 32 pins, QFN footprint (55mm), work in international opening three ISM channel of 433/868/915MHz, transfer

45、time among them is less than 650us. It adopts GFSK modulation type, rate is 100kbps. NRF905 is composed of frequency synthesizer, receiver demodulator, power amplifier, crystal oscillator, and modulator, etc. without connecting filter. It maximum transmitting power is +10dBm, maximum transmitting di

46、stance can reach 1000 meter, and has characters of high anti-jamming GFSK modulation, 100kbps of speed rate. And its inter has communication protocol and CRC, which completes all wireless transceiver communication by SPI, and its power consumer is very low, currency of -10Dbm output power is only 11

47、MA, receiver module currency is 2.5MA, free module or close module currency is 2.5A, which easy to realize low power consumer design. In addition, antenna design directly on PCB, this can improve system stability. E. USB interface circuitUSB interface is module with bridge function between up PC and

48、 work central station. One port connects USB interface of monitor controller, the other connects work central station. Because USB protocol is rather complex, we use USB controller chip to avoid trouble. USB1.1 interface tiptop transmission velocity can reach 12Mb/s. So, this system selects USB1.1 s

49、tandard, whole module is composed of USB controller, SCM, etc.USB controller is the core of USB bus interface circuit. This system selects chip PDIUSBD12 produced by PHILIPS Co. PDIUSBD12 is a capability optimization USB component with parallel bus, which satisfying with USB1.1 and DMA communication. Usually, it is used to communicate by high-speed currency parallel interface based on microprocessor system. Under ba