LabVIEW rapid prototype built medical equipment

The 21st century is the century of the life and health, life sciences and the rapid progress constantly promoting human health and the disease itself, how to develop an innovative healthcare electronic equipment has become one of the focuses of the study.

Medical device research content involves many engineering research fields such as electronics, computer, information processing, optics, precision mechanics, etc.

With the medical treatment of the development, diversification and related engineering field technology continues to progress, medical electronic devices are becoming increasingly complex. General major medical device composed of multiple subsystems, the need to integrate a variety of sensors, machinery parts, electronic components, such as FPGA or microprocessor, etc, but also involves a variety of professional bus and the Protocol, its research and development cycle is quite long and may take 2 years to 3 years or even longer. So, how to shorten the whole medical electronic equipment system development time, improve the innovation degree will be market elements.

For some small companies, from fierce competition in a firm foothold and stand out is a very difficult thing.

Their core technical personnel may be experts in the field of biology and medicine, and master a certain patent or research results, but how do I in team personnel very limited circumstances, fast will patent or research results into products, and to guarantee product reliability and stability are very difficult. Therefore in the highly competitive medical electronics market, enabling rapid prototyping is the key. From another perspective, for universities, research institutes or the company's research and development institutions, they must focus on the future, have a forward-looking and innovative equipment research and development, so that researchers need to be concerned about how quickly some algorithm or theoretical research results for authentication, and to further build out the actual system until the products of their own research projects or patent industrialization, gets more support to enter into a virtuous circle.

To sum up, for medical electronics equipment developers, system itself in electronic, mechanical, sensors and other aspects of complexity and the demand of market competition, how to quickly prototype validation of research results and products of a leading to the market.

Through a unified platform to rapidly build prototype systems

System development generally can be divided into design, prototype verification, release of three phases.

Design phase for the product itself and which involves the concept of the algorithm, is a prototype verification; design of feasibility for validation or assessment; publication is the product of the final implementation. The main tasks during the design phase is determined by the development team in the biomedical, signal processing, image processing specialists or researchers use text and mathematical tools for algorithm or system design. Prototype verification phase, the main task is to be implemented on a hardware platform and verify designing algorithms and assess to further adjust the algorithm, this task is usually made with electronic engineering background of embedded system developers, VxWorks, QNX, Linux and embedded operating systems to be completed, they are using software tools and hardware platform directly related, such as CCS, VHDL, VDSP ++, etc. In general the two stages of developers and development platform is different, so the prototype phase of the developer must seamlessly design phase to attract and convert the results, if the system requirements needed to be amended or algorithm design some errors that will result in a large number of amendments to the prototype phase of the work and even rework. Therefore, the entire system development is a loop of the progressive process.

In order to reduce both the number of times between iterative stage, many development teams have taken sides move closer to each other, ask on the front of the algorithm designers on the hardware and the underlying programming have a certain understanding upfront embedded system developers also need to have some background in biology and medicine.

In this way, to a certain extent, to let the two stages between greater communication, but for developers of requirements is higher, but the lack of systematic, along with medical electronic systems became increasingly complex, cannot fundamentally solve the problem.

A more fundamental solution is to put these two phases of the transplantations to the unified development platform, which is a development platform integration algorithms and hardware: on the one hand, the introduction in algorithm design phase early hardware i/o for validation, you can find at an earlier stage and fix potential errors; on the other hand, uses the same algorithm design development environment, code can prototype verification process to be reused, thus simplifying the programming complexity, lowers the algorithm design and embedded developers, radically speed up the circulation of the progressive process, thereby reducing the system's development time.

LabVIEW: quickly build medical electronic prototype graphical platform

LabVIEW graphical development platform since its inception in 1986, has been working to simplify the complexity of the programming, the graphical programming has also become standard development tools.

For the development of medical electronics, LabVIEW provides hardware I/O introduced algorithm design, and through code reuse and commercialization, to publish embedded prototyping platform that simplifies the complexity of building a prototype system.

Interactive algorithm design emphasis on code reuse

Over the past few years, LabVIEW has extensibility into a variety of algorithms for design to better meet the needs of research and design staff.

In addition to the powerful graphical programming style, the LabVIEW now also includes a text-based math programming tools, continuous-time simulation, state diagrams and a graphical control design and simulation, model, to represent various algorithms and applications. At the same time, for digital filter and control models, digital signal processing algorithm development of interactive tools for the introduction of the medical electronics related algorithm design easier.

Signal processing is a lot of medical electronic systems critical parts, through LabVIEW and associated kits, designers can function by calling the out-of-the-box, quickly finish for example remove baseline drift, noise reduction, QRS detection, signal extraction applications, etc.

ByInteractive Quick VI (Virtual Instrument), as long as the menu is set to parameter to complete the Kaiser window FIR high-pass filter design to remove baseline drift. In order to further processing, or you can call the advanced signal processing toolkit-mania in Wavelet functions to filter out broadband noise.

For example, the fetal heart signal extraction and other more complex processing, developers can also use LabVIEW in ICA (ICA) algorithm to be applied.

As shown in Figure 1, the upper part is collected from the mother and the fetal heart's mixed-signal, and the bottom half is ICA after separation of the fetal heart rate signals.

At the same time, developers can also use LabVIEW built-in text mathematical tools to reuse existing algorithms, such as using the Mathscript node called MATLAB in development of .m file, and an interactive environment through LabVIEW on algorithm validation debugging, so with a variety of advanced mathematical and software integration.

With the introduction of the hardware i/o and fix potential problems found

As mentioned, if the system needs to be amended or algorithm design errors that will result in a large number of amendments to the prototype phase of the work and even rework.

So a solution is earlier to real-world signals and hardware into the design process, resulting in an early stage discovery and fix potential problems.

LabVIEW platform the most obvious value in algorithm design and hardware I/O a bridge is established between.

LabVIEW through the introduction of the i/o signals, and the design process and various advanced math and design software integration to help engineers to quickly add real-world data and theoretical models, thus enabling interactive design process faster, design time shorter.

Physical measurements and design and simulation completely different challenges, requirements and a wide range of measurement and control hardware tightly integrated, and to optimize the performance of processing a large number of channel data or high speed throughput.

LabVIEW through constant evolution, in physical measurement areas providing extremely high performance and flexibility to work with hundreds of data acquisition equipment and thousands of instruments and seamless integration.

Through code reuse and commercial platform to rapidly build prototypes

Most embedded systems developers currently using prototype evaluation board for system prototyping, but the prototype Board often only have a small number of analog and digital i/o channels, the also very little support for Visual, motor or synchronization capabilities.

In addition, only for the design concept of validation, designers often need special sensor or support special I/O and spends a lot of time and development resources to develop custom prototype Board.

To simplify this process, and remove the hardware verification and Board-level design amount work using flexible, commercialization of prototype platform becomes more and more embedded systems developers.

But for most systems, and prototyping platform must include the final release of the same parts, such as execution algorithms, real-time processor, used for high speed processing of programmable logic devices, or real-time processor interfaces connected to other parts. Therefore, if the commercial system does not meet all the requirements, so this prototyping platform must be scalable and supports custom. NI offers a variety of hardware platforms and LabVIEW integration, complete design, prototype verification to the publishing of the whole process. For example using LabVIEW and NI repeatable configuration I/O (RIO) equipment or NI CompactRIO platform, you can quickly and easily create a prototype of medical electronic devices.

Rapid prototype build instance: liquid nitrogen tumor therapy instrument

Medical device manufacturer Sanarus plans to develop an innovation-surgical equipment Visica2 (V2), implementation of the treatment process includes painless anesthesia, real-time ultrasound lesion localization and minimally invasive surgery.

To keep up with the product release schedule, the developers plan for four months to develop a working prototype of the system. In addition, under the investor demands, as soon as possible to achieve production to meet market needs.

Prepare the firmware for your device in General and to develop a custom circuit board cycle is very long.

Once the firmware or software layer problems will cause additional delays thus affecting the progress of your project. In addition since v2 is medical equipment that requires that the device must not contain any prejudicial to the performance of the system firmware and software errors; if not through 510 (k) certification required expendable test, the entire project will fail. Based on these requirements, you need a very reliable development programmes.

Because both integrated I/O development and programming features, CompactRIO is considered a flexible programme.

CompactRIO system consists of a 400 MHz processor, Ethernet controller, as well as the back panel of the 3 million Gates FPGA, LabVIEW FPGA Module can be on the back panel of the FPGA programming. Because LabVIEW FPGA is a graphical programming environment, biomedical engineers without VHDL experience can participate directly in the programming work. They can run in embedded controllers and liquid nitrogen pump pure resistive heating parts of control algorithm that management and control in the FPGA devices necessary input/output signals of interface, this resource allocation allows the construction of the prototype and the final system posted in the programming model is very similar to on. CompactRIO benefits clearly, the use of customized programmes need a few months time, NI programme took only a few weeks.

In addition, if you use the custom firmware, once the new demand will lead to cumbersome update process.

After using CompactRIO platform, code modifications become very easily. As the development platform is very flexible, as new functional requirements, the development process without delay. In addition, because the CompacTRIO has passed the EMC certification, this also ensures that when the prototype validation, regardless of the specialized design of EMC-related.

Summary

LabVIEW graphical development platform by providing design, prototype from algorithm to authenticate to a product launch, from software debugging and functional testing to production testing of unified environment that allows engineers and researchers can be on the same platform for product design and development, reduce cycle development and code correction, thereby speeding up the design process.

At the same time, through the CompactRIO embedded prototyping platforms, researchers can quickly be patent or research results into products, and to guarantee product reliability and stability, thus shortening the development of medical electronic devices.

Low power portable medical data recorder

Many medical applications requires no external power and data cable of the portable self-powered device, the most obvious example is the patients carry used to measure heart rate, body temperature and other health indicators of portable data recorder.

Of course, there are many complex applications even through external power supply, would need a small battery equipment secure redundant and equipment monitoring, such as hospitals, patient rooms, the environment controlled laboratory or storage device environment parameters (including temperature and humidity) continuous monitoring is required; the other portable device installation you will need an external power supply and network cable to the device easier and more flexible.

In some cases, such as the need for patients to carry medical equipment, freezer temperature detection equipment, no external power and network cables.

Portable medical equipment requirements which features? first, must be on-board power supply.

Usually available through rechargeable or non-rechargeable battery, although there are other ways (such as solar power), but this depends on the voltage and current requirements. No matter what kind of power supply, power supply efficiency must be high enough, and battery-powered portable device does not require a full load of work should be able to get to the "sleep" mode to minimize power consumption, dormant devices can be an external trigger signal or regular is "wake up", and then raise the operation rate (of course, power consumption will increase) in normal operating mode. The device should have between full-load work and "hibernate" modes of operation to perform some simple task (such as access memory or refresh LCD and LED display data), because devices typically only under certain conditions would need full-load operation capability (e.g. for sensor data filtering and decode), so that you can power and speed between a degree of balance.

Portable device even though support for wireless communication, but is not always guaranteed to be able to access the wireless network.

Depends on network conditions, a time machine in a wireless network environment, the next time it may be moved to does not have a wireless network environment, or may be caused by power outage temporarily turn off the wireless network. In these cases, if the device itself does not support wireless communication devices will need to keep collecting data stored for later upload to top level systems for data processing. There are a number of key data (such as environmental security failure data, configuration data, or device drivers) must ensure that the storage security, even if the battery fails or is removed or is missing.

Other characteristics of the portable device depends on the specific application requirements, the data can be directly through the analog sensor acquisition or through local network access to a subsystem read, portable device can only passively collecting data under certain conditions the voice alarm proactively through or to signal the alarm.

Some simple data acquisition equipment before the upload data without user intervention at all, while other devices (such as hand-held blood glucose meter or wristband-heart monitor) may require additional input and output device instead of the host system to change configurations or browse data.

Use MAXQ2010 design portable data logger

Although the industry has many options for microcontrollers, but Maxim company MAXQ series low-power microcontrollers, mixed-signal RISC MAXQ2010 characteristics that is ideal for battery-powered data acquisition devices.

MAXQ2010 have extremely low power consumption, high MIPS/mA ratio, only need a small battery current support portable applications, integrated 8 channel 12-bit ADC can collect many types of sensor data, and also supports many types of local serial interface (I2C, SPI, UART synchronous/asynchronous), can be used to access the host system and serial non-volatile storage devices, or relating to this device in the other subsystem communication.

MAXQ2010 according to the current task on computing capacity requirements by dynamically adjusting the clock frequency to change the power consumption, and when it has finished processing all of the data and events, a portable device to go to the lowest power consumption of Hibernate (stop) mode until you wake up again by application.

MAXQ2010 nuclear voltage only 1.8V, can greatly reduce power, 3V independent power supply of I/O can communicate with the external high-voltage logic. If you want to use as the lithium battery 3V button this single supply and do not want to use the dual power supply, you can use built-in integrated voltage regulator to nuclear power. In stop mode, the voltage regulator can be turned off to reduce power consumption.

MAXQ2010 to a variety of ways to read data from the sensor, if acquisition of analog sensor data, and can use built-in 12-bit ADC, multi channel support, 8-channel single-ended input.

MAXQ2010 from external sensors collecting data can be stored in backup battery-powered RAM or internal flash memory. On-chip clock based on real-time 32kHz (RTC) in the stop mode can work, according to the timescales for the data provider. If you want users to enter data or information that is displayed to the user is able to achieve MAXQ2010, it has a set of general purpose input/output pin (the largest packaging has 56), you can drive LED, read the mechanical switch settings, or scan through the ranks of the connected switch matrix. MAXQ2010 also has an LCD controller, you can direct drive 3V-segment LCD that supports up to 1/4-cycle multiplexing (COM1-COM4), its largest package provides 40 specialized driver pins, in 4 times the multiplex mode can drive 160 segment LCD display.

The data recorder based MAXQ2010 design examples

Like many used to collect or store data in the electronic device based on the data recorder adopts MAXQ2010 USB interface with the host (PC) communication.

However, because no USB interface MAXQ2010, we use FTDI FT232R chip company achieve USB adapter with UART.

Adopt the FT232R can give loggi design brings many benefits.

First, when the USB bus activity, The data logger can take advantage of the FT232R 3 .3V regulator output power supply, only one can be against diodes and battery-powered automatic switching, and because the regulator output (minus 0.2V diode forward voltage drop) voltage than the battery voltage after subtracting the diode drop in voltage high so that you can connect to the USB bus, the recorder no battery and power supply via USB Vbus. Takes two diodes (Figure 1) is to prevent a battery, output capacitor used to lower the load transient effect on the battery. Secondly, MAXQ2010 can utilize two serial interface (UART) in a direct and runs on personal computers, application communication, does not require any additional driver. Two serial ports by a built in USB connector on the virtual COM port connections. This design uses MAXQ2010 32kHz FLL based crystals as their own clock source (if you need to provide for RTC timing), it costs less than other crystals or resonant circuit costs are much lower. FLL circuit corresponds to a multiplier coefficient multiplier for 256, 32kHz Crystal oscillation frequency to 8.388MHz as MAXQ2010 clock.

Is calculated based on the data logger is MAXQ2010 consumes much current, can be considered: first, an external signal (such as buttons or sensors voltage jumps) micro-controller to wake from the stop mode; the system then through a single ADC channel read analog sensor voltage, the acquisition of sensor voltage values are stored in the data in RAM; at this point in order to save power, the micro-controller to return to the stop mode, but in about 60 seconds, the arousal of micro-controller was again (back in step 1).

Therefore, the calculation of the average current consumption and estimated battery life need microcontroller following parameters substituted the formula (1): tActive (complete all operations, including entering stop mode), iActive (this period of typical current values), tStop (keep stop mode), iStop (stop mode typical current), tExit (from stop mode is wake-up time), iExit (was woken by the typical current).

(tActive × iActive) + (tStop × iStop) + (tExit + iExit)

tActive + tStop + tExit

According to the above parameter values can be calculated from the average current of approximately 202nA; that is, if the power is an ordinary CR2032 lithium battery, the battery life can be estimated as 1138 hours.

Different battery manufacturers production of battery characteristics vary, CR2032 battery in 90% of discharge interval not exceeding 0.3V pressure drop, which means that the battery voltage drops to 2.7V before (after a diode drop back to 2.5V, meet single-supply operation at minimum voltage), micro-controller can work in 1024 hours.

Increased battery capacity or quantity, use rechargeable batteries, or when you are connected to the USB charging, etc. automatically while many measures are used to extend the battery life.

General average current is only slightly higher than the stop mode, the standby current, this is because the stop mode time far longer than the time the program runs, stop mode of the current play a leading role. Program loop code can be extended, such as measuring multiple sensor values or add other features do not significantly change the battery life. Of course, the use of other peripheral functions, such as LCD displays, LED indicates or serial port, and so will increase the power consumption, designers in the calculation of the actual battery life when you need to consider these features may increase power consumption.

Based on RF transceiver for implantable medical devices

Zarlink Semiconductor company for pacemakers, Nerve Stimulator, pump and other implantable medical devices applied a ultra low power RF transceiver chip, the data transfer rates, low power consumption, with unique wakeup circuit.

This article discusses how to use the RF transceiver for intimate communication system design.

Integrated circuit (IC) and medical device development over the past 30 years has been developed at the same time.

Circuit technology contributed to the development of increasingly complex, highly integrated and compact medical device development. At the same time, health care costs continue to rise and people living in the more affluent, more fat in the body, as well as longevity, have had to rely on the base station wireless connection of implantable medical devices of new application and treatment needs. Traditionally, implantable medical devices of communication system uses very short magnetic coupling, which requires the programmer and medical equipment to tightly coupled, usually data rate is lower than 50kbps.

In order to overcome the distance limits 402MHz ~ 405MHz medical implant communication services (MICS) band in 1999 enabled, then Europe would appear similar standards.

The band was possible with long distance (usually 2m), relatively high speed wireless link. In the human body due to signal transmission characteristics, and the band working user work-compatible (such as meteorological balloons, and other auxiliary meteorological equipment) and global availability, 402MHz ~ 405MHz band is ideal for this kind of service.

For implantable medical applications of the electronic system of the enormous difficulty of low power design.

For example, the vast majority of implantable pacemaker life require longer than seven years, the maximum leakage current in 10uA ~ 20uA magnitude. Because of the need to support the pacing and on current consumption requirements, communication systems current design of the equipment within the overall average life current does not exceed the total amount of the current design, i.e. 15% 2uA ~ 3uA. Implantable medical system of transceivers must periodically "view" or monitoring external communication devices, in the view, at a very low-power state to save energy.

Design considerations

In order to be able to use MICS band, implantable medical devices requires the use of ultra low power, high performance transceiver.

Implantable device transceiver design face numerous challenges, including:

(1) 400MHz communications for low power.

Implantation of battery power is limited, and implanted battery impedance is relatively high, which limits the current from the battery slot. (2) the communication phase, for the majority of implantable devices, should be less than the current limit in 6mA. (3) is sleeping and periodic "view" to wake-up signal, at a low power. (4) the minimum of external components and physical volume. Implantable-level components of expensive, high integration can reduce costs and increase overall system reliability. (5) data transfer rate is reasonable. Currently, pacing requirements for data transfer rates greater than 20 kbps, the future design of data transfer rate is much higher. (6) systems and data transmission reliability. (7) the selectivity and interference suppression capabilities, in particular, TETRA radio standards in Europe. (8) distance typically more than two meters. The longer the distance requires sensitivity to the better, because small antenna and the effects of loss and allows distance link budget. Antenna, matching, decay and loss of changes are large, losses may be as high as $ 40dB ~ 45dB.

ZL70101 MICS transceiver in the high data transfer rate of cases with excellent low-power characteristics.

Up to the data rate 800kbps, transmit and receive current is less than 5 mA. Circuit has a unique work in 2.45 GHz ultra low-power wake-up system, an average of sleep/monitoring current less than 250nA. System integration, just need three external components (Crystal and two decoupling capacitor) and a matching network.

Medical devices can be divided into an internal non-rechargeable batteries (such as a pacemaker) class and inductive coupling power class (such as cochlear implants).

The former is strongly mining system duty potential to save power. Transceiver for most of the time is off, so off current and cyclical find communication equipment need current must particularly low (< 1-2uA). At the same time, the two situations of the transmit and receive power is low (current < 6mA).

In 2.1V ~ 3.5V power voltages, ZL70101 peak current consumption receiving/transmitting 5mA, this < include basic RF transceivers and MAC current.

MAC to ensure that users receive high integrity data, automating the most link maintenance work. In addition, the MAC Protocol provides a savings in power, transmission of a packet of timer, the timer will be implanted device receiver off for some programming good time.

To enable to joules/bits defined total power consumption minimum, meet the requirements for using the receiver sensitivity, recommended implantable transceiver using data rates as high as possible.

Need a low data rate (or even low kHz range) systems should be buffered, working at the highest possible data rate, lower duty cycle to reduce average current consumption. To send a short pulse data saves power, reduce the time window of interference. In addition, the high battery impedance system, because a pulse from the capacitor discharge shorter power on decoupling requirements may be lower.

Transceiver allows users with the receiver sensitivity, from a variety of data rate (200 kbps to 400 kbps and 800 kbps).

In order to achieve this flexibility, the system uses 2 FSK modulation FSK or 4, 200 or 400 thousand characters, variable frequency deviation (see table 1). Through the use of film, digital filtering, you can reach the lower the number ofAccording to the rate and the corresponding higher receiver sensitivity. Transceiver has a MAC bypass work mode, in which radio frequency is fully available. In this configuration, users can develop custom protocol and data transfer rates.

Overall system architecture

ZL70101 works in Implantable devices and external base station (see Figure 2).

Base station includes emission 2.45 GHz wakeup signals of additional circuits. System once adopted 2.45 GHz wakeup signal start, through 402MHz to 405MHz MICS band transceivers and Exchange data.

ZL70101 MICS chip (see Figure 3) contains the three major subsystems: a 400MHz transceiver, a wakeup receiver 2.45 GHz and a media access controller (MAC).

According to the input pin of the State determines the chips used for implantation medical equipment, or base station Programmer's transceiver.

Transceiver with an intermediate frequency (IF) low band image rejection mixer superheterodyne structure.

Low-medium frequency allows filter and modulator minimum power consumption, and high data rate, zero-if architecture related flicker noise and DC offset. FSK modulation scheme reduces emission linear amplifier, thereby reducing power consumption, and you can use the simpler by limiting the receiver. As Figure 3 won the bid to half-duplex RF transmitter with 400 MHz transmitter subsystem contains a medium frequency modulator, a mixer and a power amplifier. IF modulator will be a one (two FSK) or two (4 FSK) asynchronous digital input stream into intermediate frequency. Upconversion mixer will convert the RF frequency medium. Note that transmit and receive mode is the same as the local oscillator frequency, allowing and dead time between.

You can register custom-4.5dBm ~-17dBm (500 Ω load), the step to less than 3dB programming emission power amplifier output power.

All RF input capacitance of internal antenna matching group can fine-tune match network, for a given power settings to achieve the maximum output power, receiver noise index best. Antenna tuned to automatically scale, which takes a peak with the ADC coupled detector, take one of the calibration control state machine.

400MHz receiver subsystem MICS band signal amplification, the carrier frequency transformation to MF.

Low noise amplifier (LNA) gain to 9dB ~ 35dB programmable. On implantation medical equipment transceiver, it is recommended that a higher gain settings, and the relatively low number of gain settings can be used to select the use external LNA's base station transceiver. LNA and mixer bias current of programmability that optimization is ideal for linear (IIP3), power consumption and noise index of flexibility.

Multiple phase IF filter to reduce the frequency and adjacent channel mirror interference, and limits the noise bandwidth.

Polyphase filter after the next limiting and a receiver signal strength indicator (RSSI) module. RSSI measurement consists of a 5-bit ADC conversion, you can use industry-standard SPI interface reads. The MICS no interference channel assessment program. Note that you must first define by MICS standard without interference of a channel assessment procedures with an external instrument to determine an appropriate available channel.

To do this, also developed a highly reliable medical applications customized private agreement by MAC address, including the following major features:

(1) use Reed-Solomon forward error correction (FEC) and cycle redundancy code (CRC) error detection techniques for error correction and detect.

Suppose the original radio BER 10-3, FEC and CRC after effective BER 1.5 × 10-10. (2) fault situations block to automatically transfer, and process control to avoid buffer overflow. (3) the ability to send emergency orders and MICS high priority information. (4) be capable of processing link watchdog to ensure that the communication was not successful for 5 seconds after the broken link. (5) provide link quality diagnostic and auto-calibration control.

Ultra low-power wake up the receiver

Because storage battery energy is most important, most embedded applications are seldom MICS on the RF link.

In the extremely low power applications, most of the time, the transceiver is a current very low sleep state. In addition to send emergency command, use MICS band systems must not interfere with channel assessment program, wait for the base station to start the communication. Implantation transceiver should periodically query base station do you want to communicate.

Wake-up system is a work in 2.45GHz SRD bands of ultra low-power RF Receiver, detect and decode a special packet, the packet from the base station Launcher, and then connect the remaining power chip.

Chip can also be started directly by pin control, such as base stations start, implant device sends emergency command or using selective wake-up system implantation equipment requires this way.

A brief summary of this article

Ultra low-power wireless technology for many implantation medical equipment it is critical, including pacemakers, defibrillators, Nerve Stimulator, drug infusion system, diagnostic sensors and rapid growth of implantable Diabetes Monitor.

However, with the implanted communication systems development and support of advanced diagnostic and treatment, and wireless performance on implantation medical device battery life does not affect is critical.

High-performance, low-saturated linear regulator (LDO) development

The whole equipment continuously miniaturise and provincial electricity, power consumption, small low dropout linear regulator (LDO) is becoming a switching power supply with linear regulator market mainstream. In order to achieve high performance and high speed, internal use of micro-computer or digital signal processor (DSP) technology has advanced by leaps and bounds every year in progress and development, at the same time, these micro-computers or digital signal processor essential power supply voltage is lower and lower. In addition, different manufacturing process corresponds to the voltage of the respective differences, and therefore requires a wide range of power supply voltage. To resolve this problem, the manufacturer started in the Middle voltage switching power supply setting, use LDO regulator with LSI power of new technologies. On the other hand, in the battery device also uses a large current LDO regulator in order to maximize the efficient use of battery voltage.

Use the DC/DC converter from obtaining high input power voltage 5V or so, and then use the linear regulator buck into 3.3 ~ 1.0V voltage, which is the usual power structure.

Such regulators are called subordinate linear regulators, in need of such a power structure to the device near a low input voltage supply more stable power supply. ROHM developed BD □ □ KA5 series product is suitable as a secondary linear regulators (Figure 1).

Secondary voltage regulator is seeking to further save space and more secure at the same time, constantly improve it in order to adapt to the DSP components such as narrow input voltage range and the high accuracy of must.

BD □ □ KA5 series 500mA current capacity while only, but the output phase compensation capacitor can support 1 μ F small ceramic capacitors, saves the space taken by regulators. At the same time, through the use of ROHM proprietary trimming techniques, the output voltage accuracy improves ± 1%. In addition, through the use of P-Channel MOS transistors as driven output transistors, even if you increase the load current to control circuit current and thermal design. Power supply input range is the most suitable 2.3V-5V 3.3V, 5V power supply input range. In addition, the output voltage specifications including 1.0V, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, adjustable input type and low voltage output, etc., products to meet different needs.

On the other hand, from battery direct gets output voltage standard fixed output and adjustable output remains essential, its peak output current of increasing every year.

ROHM's BA □ □ DD0 series is to have the current capability of LDO 2A (Figure 2). The series of achieving high output current of 2A, the output voltage accuracy improves ± 1%, and low-voltage 0.5V. Corresponding input voltage changes, avoiding the output voltage is lowered to low input voltage limit, ensures low voltage output started. In addition, the industry-standard pin configurations 78 series and ROHM previous 1A low saturation voltage regulator-compatible, easy replacement. Input voltage range (3 ~ 25V), output voltage range is from 1.5V, 1.8V, 2.5V, 3.0V, 3.3V, 5.0V, 9.0V, 12V to 16V.

Equipment in order to reduce power consumption without working part, in each region cut off the power of power management.

BD □ □ KA5 series and BA □ □ DD0 series of all models, all with under external logical interrupt all lines of shutdown switch function, the standby current consumption 0 μ A (typical), in favor of a low-power design.

These two series LDO regulator products have built-in protection circuits are as follows:

1. overcurrent protection circuit.

The use of automatic fall-protection circuit. If the overcurrent protection circuit starts to work, the output voltage drops, more focused output current, and hanging-type protection circuit can be compared, is short circuit, exception state chip heat consumption control in 1/3 ~ 1/5 (see Figure 3).

2. temperature protection circuit.

Temperature protection circuitry on the chip temperature exceeds Tj = 150 ° c automatically stops the output and to prevent overheating and damage caused by the chip, so as to achieve the purpose of the protection of the chip. If the chip temperature drop, you have to recover the hysteresis width output (Figure 4).

3. the overvoltage protection circuit.

Overvoltage protection circuit is built-in in BA □ □ DD0 series products, if the output appear above 25V, surge protection circuit starts to improve chip components pressure resistance, even if the input voltage exceeds the 50V, is also able to prevent chip damage (Figure 5).

4. high static pressure.

Output of electrostatic discharge pressure for human body model, you can achieve more than 6KV, in any environment with a high reliability.

Infrared body thermometer circuits design

Because medical needs, in many cases, normal thermometers have satisfied a fast and accurate temperature measurement requirements, such as the station and airport, population density and a great place for the measurement of body temperature. Although now abroad this temperature measurement technology is more mature, but internally the technology is still in development stage. Therefore, in order to adapt to the needs of medical development, effective special environment temperature measurement, thereby effectively control and prevention, such as SARS, special spread that there is an urgent need to design a temperature measurement speed and accuracy of the thermometer. For general industrial use of infrared thermometer accuracy is not high enough, according to this principle of infrared temperature measuring, through key device choice, aiming system design, and temperature compensation automatically adjusted to improve the accuracy of the infrared thermometer, designed an infrared temperature measurement circuit for the personnel-intensive and the flow is large fora rapid body temperature measurement. 1 infrared temperature measurement principle of nature all temperature is higher than absolute zero (-273.15 ℃) objects, as molecular thermal motion of all keep the surrounding space radiation including infrared band, electromagnetic waves, its radiation energy density and the temperature of the object itself between radiation law. Group-radiation-radiation law principles: type: E-radiation emitting ° W/m3; σ to Stephen-Boltzmann constant, 5.67 × 10-8W/(m2 · K4); ε is an object's radiance; t is the temperature of a body, K; T0 to objects surrounding environment temperature, K units. Measurement of the emission of E, can reach the temperature. Use of this principle of temperature measuring instruments called infrared temperature meter. This measurement does not need to contact the measured object, therefore belongs to the non-contact measurement. Infrared temperature meter measuring range is very wide, ranging from-50 ° c up to more than 3 000 ° c. In different temperature ranges, object of the wavelength of electromagnetic energy distribution, at room temperature (0 ~ 100 ° c) range, the energy is concentrated mainly in the mid infrared and far infrared wavelengths. For different temperature ranges and for different measuring object, its specific design. According to the type (1) principle, instrument measured by infrared radiation:-: A for optical constants, and the specific design of structural instruments; ε 1 to be logging object of radiation rate; ε 2 for infrared thermometers of the radiation rate; T1 to the measured object's temperature (K); T2 for infrared thermometers for temperature (K); he is represented by a built-in temperature detection components measured. Emissivity ε is the one used to express the capacity of the emitted wave coefficient, a scale from 0 to 1.0. The best radiation is the radiation rate 1.0 objects, physically called blackbody. This is a theoretical concept, in fact, there is no object of the radiation rate can reach 1.0. But can produce extremely close to the actual ε = 1.0 blackbody calibration for thermometer. All real objects, including all parts of the body surface, its value is a ε below 1.0 values. As ε value extremely difficult to measure but not sure, the meter measured E, press-(2) calculated T1 there will be errors. In practice, the instrument is in ε = 1.0 blackbody calibration on a good factory, measurement of ε = 1, its indication that the object represents the object's actual temperature, if the object does not equal 1 ε, meter readings do not represent the actual temperature, the object should be amended. Radiation wavelength in the human body primarily 9 ~ 10 μm infrared, through the body's own radiation measurement of infrared energy, will be able to accurately measure the surface temperature of the human body. Because the wavelength range of the light is not absorbed by the air, thus the use of human radiation infrared energy to precisely measure the surface temperature of the human body. The body of the infrared radiation and he's surface temperature has a very close relationship, therefore, through the body's own radiation measurement of infrared energy, will be able to accurately measure the surface temperature of the human body. Infrared temperature measurement technique by the biggest advantage is the test speed, 1 s within the test is complete. Since he only receive human foreign emission of infrared radiation, no other physical and chemical factors on the human body, the human body without any harm. 2 structure diagrams and circuit design 2.1 structure diagram design as shown in Figure 1 as a design system architecture diagram. 2.2 temperature sensor for temperature measurement device using the infrared sensor, he is able to receive objects emitting infrared and converted into a voltage signal. I use a unit of Pyroelectric sensor PM611, this sensor is single-sensitive element, because he uses a receiver element and two parallel compensation element threaded structure, it can also be effective compensation environment temperature fluctuations, the effect of vibration is disturbing. He's working temperature is-20 ~ + 70 ° c, especially suitable for measuring body temperature. And the index are PM611, so use his temperature meter probe. As shown in Figure 3: the sensor D, S, E, respectively, and the markup in the circuit diagram D, S, E connection. 2.3 measurement circuit for measuring circuit shown in Figure 4. 2.4 integral circuits in the analog signal into a digital signal, select the ICL7106 integral-type A/D converter. He mainly has the following advantages: the integral-type A/D Converter Convert high precision, low cost; his precision and integral resistance, capacitance of precision-independent integral, it can reduce the quality of the components; requested against the interference ability; his peripheral circuit is simple. However, there are also some disadvantages ICL7106: baseline power changes directly affect conversion accuracy, when chip voltage reference within the General temperature influence is relatively large, when accuracy is high, you should use an external reference voltage source; the working speed is low, generally 1 ~ 20/s. So the main features of the integrated ICL7106, especially in order to improve the precision, the design uses an external reference voltage source. In addition, because for fastest measurement speed is 1/s, ICL7106 work speed lower disadvantage on our design has no effect, but his advantage is well suited to the needs of design, A/D ICL7106 is converted. 2.5 LCD display shows part of the circuit by many liquidCrystal display drive ICL7106 and standard-LCD EDS801 and other components. 3 debugging in the experiment by regulating A1 output 10 k Ω rheostat for A3 size of the output signal is changed, when A3 output less than 2.0 V, you can adapt ICL7106 quantum 2.0 V work characteristics, therefore two A3 potentiometer to adjust the size of the A3 output, make sure that when the temperature does not exceed 2.0 V. Debugging, using a known temperature (20 to 70 ° c) before the object is placed in the probes, regulating ICL7106 section of R12, LCD display the correct temperature, and a known temperature, continue to adjust the potentiometer, the displayed value is equal to a known temperature value accurately and repeatedly adjusted several times. Note do not exceed PM611 sensor and ICL7106 D A/Integrator temperature limit.

Measuring multiple physiological parameters of the wireless terminal medical monitoring system

Multi-parameter monitor is important in clinical nursing unit, it can monitor the patient ECG, blood pressure, oxygen saturation, pulse rate, respiratory rate and temperature, and other physiological parameters. At present, domestic universal use with CRT or LCD displays have a portable monitor, this instrument is capable of performing real-time data and waveform display and operations more flexible, so it is used primarily to help doctors diagnose and analyze the patient's condition. However, due to its large, power consumption is high (add 220V AC or built-in current), it is not easy for patients to carry, even cannot simultaneously on multiple patients care. This article is designed for wireless distributed medical monitoring system will leave no stone unturned to compensate for the inadequate. The system with three separate OEM modules for measuring physiological parameters, each module separately and a wireless transceiver function control display module connected to constitute a separate device, so each module in a significant reduction of power consumption, which are correspondingly reduced. Patients can choose according to the different needs of different modules, each module on the LCD screen can be displayed measurement signal correctly. All of these modules with PC for wireless information exchange, PC can give each module registers a unique serial number, and you can access the information for each module, the information store, analysis, display, press q, etc, this is easily achieved many modules extend that to achieve this more real-time monitoring of patients. 1 system structure and working principle of the system is mainly composed of hardware and software, two-part. Hardware including PC and three independent modules that the module ECG module, oxygen and blood pressure modules, each of these three modules are controlled by the OEM module and show transmission modules. ECG module mainly used to measure ECG, respiration rate, body temperature, and other parameters; oxygen module mainly used to measure the blood oxygen saturation and pulse rate, and other parameters; oxygen module mainly used to measure oxygen saturation and pulse rate, and other parameters; blood pressure module used to measure blood pressure parameters. Software parts mainly PC central monitoring software, including databases and user interfaces. Figure 1 is a wireless terminal medical monitoring system structure diagram. Figure 1, the OEM module and PC through wireless transmission module for serial port communications to exchange information. The OEM module acquisition of data on PC for processing after being stored. Users can be in central monitoring software interface, select any of the modules view real-time acquisition to data or waveform, software can automatically analysed the data, unusual alarm signal in a timely manner. 2 the module functions and features 2.1 control displays the transfer module control displays the transfer module to Atmega161 microcontroller core, an external graphic LCD module WGM-12864, press and NRF903 wireless transceiver modules. Its circuit structure as shown in Figure 2. Atmega161 is Atmel company produced a low-power CMOS 8-bit single chip RISC, its performance 1MIPS/MHz, 16K bytes of FLASH, 512 bytes of EEPROM, 1K bytes of memory, 35 common i/o port, 32 universal working registers, three timers, internal and external interrupt sources, two programmable SPI port UART, and three by the software-selected power-saving mode. WGM-12864B module is a monochrome graphic dot matrix LCD display module, dot-matrix is 64 x 128. Its 8-bit data line and the mouths of PA Atmega161, D/I indicates that the data bus on the number of signals is dot-matrix or control command words, R/W indicates that the current operation is a read or write operation, E is the control-side, RST is reset client, CS1, CS2 was around lattice district elections end. PC1, PC2, PB1, PB0 to function keys and LCD together to form the menu style of human-computer interaction interface, control the corresponding OEM module. In work mode LCD displays from OEM module Gets the information of related data. NRF903 module is a wireless transceiver modules. NRF903 is a NORDIC company launched single-chip wireless transmit/receive one chip that uses Bluetooth (Bluetooth) core technology and design, a 32 foot chip includes a three-stage high frequency emission, high-frequency receiver, PLL synthesizer, I/Q modulator, I/Q demodulator, multiple channel switching, asynchronous communication interface, its programming interface CFG_CLK (configuration registers clock), CFG_DATA (configuration registers data), CS (configuration registers pieces selected) and SPI port Atmega161 PB7 (SCK), PB5 (MOSI), PB4 (SS) connected to the operating frequency, channel, output power and output clock frequency and other parameters to program settings. Set CS to high level, from 14-bit microcomputer control word in each CFG_CLK programming mode clock signal rising edge, CFG_DATA end logical value written to the configuration register, the programming information is loaded, the parameter is set to complete. STBY, Atmega161 PWR_DWN respectively and PD6, of, you can set PD5 as a standby or power-down mode. Data interface for DATA and a UART1 mouth Atmega161, used to receive and send data. TXEN feet and connected to PD7, used to control the sending and receiving of data. 2.2 ECG OEM module ECG OEM module adopts Beijing multran Tong Yuan electronic instrument co., Ltd of BT007 seven channel ECG strips. BT007 to automatically measure the human heart radio, respiration, heart rate, respiration, etc, body temperature, and other parameters, has the following characteristics: synchronization seven channel heart radio, four programmable gain, three-level filtering mode (diagnostic mode, guardianship, surgery), Bo pulse suppression feature, leads off the alarm, heart rate range 20-250BPM, defibrillation and electric knife interference, impedance respiration, respiratory rate range: 5-99BPM; dual temperature measuring, measuring range 0-50 ℃, the display precision 0.1 ℃, measurement accuracy 0.2 ℃. Communication with the user interface and UART serial port, there are two communication protocols: synchronize three-channel synchronous ECG Protocol and seven passChannel ECG Protocol, you can choose via jumper. Synchronize three-channel ECG Protocol features: 19200 baud, 8 data bits, 1 start bit, stop bit, no parity bit; synchronization seven channel ECG Protocol features: 28800 baud, 8 data bits, 1 start bit, stop bit, no parity. You can send to the MCU control word for the module, control the gain, filtering mode ECG; ECG plate data sent to the MCU to 1 byte header and a number of bytes of data as a group, the group header is sent, which is 251-254, digital byte is 0 ~ 250. MCU can categorize the data storage, analysis, display and transmission to the PC in real time. 2.3 oxygen oxygen OEM OEM module module using Beijing multran Tong Yuan electronic instrument co., Ltd of DIGISAT g1b module. The module via the UART TTL port for communication with MCU. It can provide the following data: arterial oxygen saturation, pulse rate, volume scanning, bar graph, signal strength and status information. Its communication protocols and BCI communications protocol compatibility, data transfer, the transfer to the baud rate 4800bps format: 8-bit data + odd routing baud rate, transmission format for 4800bps: 8-bit data + parity bit + 1 stop bit. The MCU per second sent 60 packets and each packet is 5 bytes. 2.4 OEM OEM module blood blood pressure module using Beijing multran Tong Yuan electronic instrument co., Ltd of BTN602 noninvasive blood pressure measurement module. The module also TTL level of UART port to communicate with the UCM. To receive an external command, complete the appropriate operation, and returns the system status and corresponding data. Data format: start bit + 8 data bits + 1 stop bit, no parity, baud rate 4800bps. 3 software system design – central monitoring software the software using VC language design. In the past with the hospital management system, in accordance with the principle of unified standards, enabling a new combination of old system, fully guarantee the original system of independent reliability, modular software architecture and refactoring. The system administrator will first need to be patient information manual input to your computer system in which critical information saved to a central database server; then key in the database data, statistics and classification. According to the category of the data is replicated to all sectors of care center database, when you start monitoring needs, start-to-patient wards and records. Patient monitoring data and alarm level can be adjusted according to the care you need. Query, display key data and images, and the key to query data in a memo, image annotation, you can batch print output key data and image files. Its software system structure as shown in Figure 3. System security controls mainly from three aspects to guarantee the security of your database, image file security, user security permissions. Built on the NT Server on a database server SQL Server enables users and database operations staff login to authenticate. Only use a database user account and password for the login of the user to manage and maintain the database, users on different tables with different levels of permissions. File server uses port control access, guarantee the security of the file server. System software through wireless transceiver modules, using polling of data acquisition module, the low end if system in query timed patient information, skip this module queries, the query into other modules, the software records the query failures, when query failures exceeds a certain threshold, the system issues a warning signal.

Embedded WiFi technology in the medical monitoring of programmes

Currently, IEEE802.11 wireless local area network standard in voice communication, wireless, Office, etc are widely used, but mainly limited to PCs, laptops, and other common platform of wireless communication.

Wireless LAN in the electronics, industrial control, mobile handheld devices such as embedded application requirements in your environment. How do I in embedded system integration of WLAN broadband communication, become embedded system applications in a hotspot.

1 IEEE802.11 wireless LAN IEEE802.11b series including IEEE802.11, IEEE802.11a, IEEE802.1lb, IEEE802.1lg four standards.

This stage of the product more IEEE802.11b. This article is targeted at IEEE802.1lb standard, describes an implementation of embedded WiFi.

IEEE802.11b standard is in IEEE802.11 developed on the basis of the work in 2.4 GHz band, using CCK modulation technology, the highest transfer rates up to 11 Mbps, with deployment easy, reliable communication, strong anti-interference ability, low cost, flexibility, and portability, high throughput, and other characteristics.

It allows wireless users can get the Ethernet level of network performance, speed and availability, and can be seamlessly integrated in a variety of LAN technologies will produce a maximum meet user demand network. WiFi is the abbreviation of Wireless Fidelity, IEEE802.11b wireless standards exclusively. In introducing the work mode IEEE802.11b, first describes the basic concepts.

1.1 IEEE802.11b basic concepts

STA is the access portion of the wireless media, often called the network adapter or network interface card.

STA can be mobile or fixed. Each STA support authentication (authentication), authentication (deauthentication), encryption and data transfer, etc.

Basic service set BSS (Basic Service Set) is the basic form IEEES02.11b LAN, basic service set cell can contain multiple STA.

BSS basic service set has a coverage. In the coverage of basic service set STA can maintain mutual communication, each BSS has a basic service set identification number BSSID.

Independent basic service set IBSS (Independent BSS) is the most basic type of LAN IEEE802.11b, a minimum of IEEE802.11b LAN can only contain two STA.

In this mode, the STA to direct traffic. Because this type of IEEES02.11b LAN usually necessary arrangements so that the network mode is commonly referred to as ad hoc (Latin, translated as "ad hoc") mode. Site (STA) and basic service set (BSS) relate is dynamic, STA free to power on, power off, enter or leave the BSS coverage.

DSS (Distribution System Service) used to connect multiple BSS.

Due to the physical layer coverage limits determines can support of STA and direct communication between STA. To solve this problem, the introduction of DS (Distribution System), it can take multiple BSS constitute an extension of the network.

Access Point AP is short for General translation of "wireless access node" or "bridge".

Mainly in the media access control layer MAC play wireless workstation and wired local area network of bridges.

ESS (Extended Service Set), DS and multiple BSS allows IEEE802.11 constitute an arbitrary size and complexity of wireless network.

IEEE802.11b put such a network is called extended service set network. Similarly, the ESS also has an identifying name, i.e. the ESSID. 1.2 IEEE802.11b work patterns

IEEE 802.1lb has two working mode: Ad-hoe and Infra-structure model.

IEEE standard in stand-alone basic service set (IBSS) to define Ad-hoc mode of client-side collection, to basic service set (BSS) to Infrastructure mode defined by the client-side collection.

In Ad-hoc mode, the client cannot directly and the network of other client communications.

Ad-hoc mode is designed so that in the same spectrum coverage of customers can communicate with each other. If an Ad-hoc network mode customers want and the network of customer communications, the network must have a customer gateway, and performs routing functionality.

In Infrastructure mode, every customer will have their communication message to forward all communications AP.AP message.

These messages can be sent to Ethernet, can also be sent to the wireless network. This is an integrated Ethernet and wireless network infrastructure for application mode. Wireless access node is responsible for the management and roaming, and other bands command work. An AP connectsto 1024 site.

2 the design of embedded WiFi

Embedded WiFi structure and standard PC/OS platform.

To common microprocessor/microcontroller on WiFi communication, its hardware structure, software level must be reduced. The following spoke: Prism MAC instructions embedded WiFI design for software and hardware.

2.1 embedded WiFi hardware design

Embedded environment WiFi hardware interface as shown in Figure 1.

Compared with standard platforms, no PCMCIA Bridge. Figure 1 is an embedded environment PC2MCIA interface card and bus connections open MCU.

Since MAC including Memory space Prism and I/O memory two space, so you will need two films selected by or door control read and write space of choice.

PCMCIA package Prism MAC 26 root address line driver Prism MAC only needs to address lines A0 to A9, other address all grounding line. For bus not open processor, you can use the I/O port line simulation approach to reading and writing.

2.2 embedded WiFi software design

In Linux, WinCE, operating environments, you can use the manufacturers to provide the device driver to use the WiFi card.

This system is generally on hardware resources (such as CPU performance, storage capacity, etc) have higher requirements. For many embedded applications, due to a hardware resource limitations, many systems are simple OS (such as uC/0S etc) or no 0S environment running, then you need the entire software protocol for appropriate reductions.

TCP/IP protocol implementations in many articles have been more telling.

Here the main Prism MAC, for example, introduce infinite network drivers, namely embedded WiFi drivers.

Prism MAC provides consumers with a set of interface registers, registers, and through these Prism MAC for communication.

These registers is located on the Attribute Memory [2] space, you can use the direct access Memory address AttribLlte. Table 1 lists the commonly used registers PRISM MAC and its definition.

In order to read and write these registers, defines two functions: unsigned int getReg (unsigned int reg) and void selReg (unsigned int int val reg, usnigned).

Prism MAC drive is to command registers a command to manipulate MAC. Frequently used commands are allocated buffer, query the network card status, initialize the card, read data, write data, etc.

Prism MAC driver needs to provide for the upper MAC read and write functions, and some control function, the implementation of the function prototype is as follows:

void init_mac(void) void reset_mac(void) WORD wc_write(WORD*buff，WORD len) WORDwc_read(WORD*buff，WORDmaxlen) B00L get_wlan(void)

Reset_mac (void) is used to start the system or the system needs to be reset, reset Prism MAC while driving the use of a variable is initialized.

Inh_mac (void) function finishes initializing network controller and firmware to the NIC controller application for the use of the buffer required for the preservation of the RID. Wc_write (W0RD * burf, W0RD len) function in the buff len bytes written to the send buffer, MAC, and then write send command to send the command registers the network card, the function returns the actual length of data sent. Wc_read (WORD * buff, WoRD maxlen) function receives the input data. Returns the actual length of the data received, on the upper-layer protocols, call wc_read, can the data in the buff do protocol analysis. For TCP/IP, actually removed may be IP, ARP, and other types of messages. Get_wlan (void) by accessing EvStat register determine whether data is received, returns to judge the results. If so, you have the income to PrismMAC data frames share the data area. This function simply PrismMAC data frame first read out the fairly so Ethernet frame's header. Readout of data format for upper-layer protocols call get_wlan later, if the return value is TRUE, you can access the destination address, source address, the frame type and other variables to determine whether processing the data received. If you need to receive data, you can call the wc — read to read the data.

3 embedded WiFi in the application of medical care

Embedded WiFi in many areas have a wide range of applications.

Here is a concrete implementation of embedded WiFi — mobile monitoring systems. The monitoring system for hospital patient care, the use of embedded WiFi technology, available in a mobile environment, to be logging objects for digit grouping, real-time monitoring.

3.1 hardware structure

Mobile monitoring system consists of a server and multiple mobile intensive care unit.

Server-side include 1 PC or laptop, one wireless AP and 1 alarm, hardware structure and connections are relatively simple, in this no longer description.

Mobile monitors hardware structure including power supply module, pressure sensor, acceleration sensor module and a wireless network card modules.

Mobile monitors using Ti's ultra low-power microcontroller MSP430F148 as CPU.

Acceleration sensor module using the AD company's accelerometer ADXL202 for acceleration test, or gravity acceleration measurement, analysis, i.e. for patient tilt down test. Pressure sensor with MotorOla medical dedicated MPX2300DT, has good features and low voltage operation for linear output pulse measurement.

Power use 3.6 V battery-powered, after simple voltage transformation to satisfy the power requirements of mobile intensive care unit.

Wireless network cards using IntersilPrism2 PCMCIA network card chip set. It is a IEEE802.11b compliant network adapter. 3.2 software structure

Ad-hoc mode, move the monitors and the distance between servers is very short.

In order to increase the monitoring range, the mobile Telemonitoring system work in Infrastructure mode, the server-side AP and mobile monitors are equivalent to an STA, mobile monitors and servers can be in different BSS. Mobile monitors, AP's BSS together constitute an ESS, use DSS communication.

Server-side software module is used primarily to received from the network to the data in separating out the tilt, mobile monitors configuration information, pulse, and according to the information to the police, to move the monitors control.

Mobile monitors major complete Acceleration (tilt) data acquisition, pulse signal acquisition, data transceiver, sensor and stopping control.

The software can be divided into two levels: the application tier and the driver layer. Shadows for hardware drivers, driver layer above is the application layer.

Mobile monitoring systems with embedded WiFi technology, supports digital grouping, you can group objects to be logging detection, real-time data transmission at the same time; guarantee the reliability and accuracy of monitoring, in actual use has very good results.