Based on embedded technology monitoring system

1 Introduction

As China's rapid economic development, urbanization is increasing acceleration, people constantly accelerating the pace of life, more and more people begin to feel the deterioration of health, many people never know until disease outbreak.

It is reported that the vast majority of people in China are in the Asia-Pacific health status. With modern electronic technology development, 16/32-bit CPU, traditional physiological signal monitors CPU system is gradually by the 8-bit CPU to a higher number of processors. With the monitor function of powerful data processing speed of the increasingly high demands, enabling the development of an 8-bit CPU was restricted, 16/32 bit CPU can be much higher than the 8-bit CPU clock frequency, data throughput, processors once prices are falling, 16/32 bit CPU began to be widely used in physiological signal monitor.

The monitoring system adopts ARM7 series chip embedded microprocessors in LPC2292, mainly used for measuring the body's physiological parameters, such as: ECG, blood pressure, oxygen saturation, temperature, etc.

Because the system requires the collecting and processing large amounts of data information and CPU used single-task software to process these data information is very difficult, even impossible. Therefore the design selection can handle multiple tasks simultaneously μ C/O S-Ⅱ operating system. It provides a secure and reliable operating system platform, reducing the development cycle.

2 system hardware design

ARM 7 series chip LPC2292 minimum system as shown in Figure 1:

System's overall structure diagram shown in Figure 2.

Figure 2 shows the entire system to ARM 7 LPC2292 series chip at the core, extended its perimeter fringe circuit, enabling the human physiological parameters: ECG, blood pressure, oxygen saturation, temperature of the security check.

System through the ECG module, blood pressure, oxygen saturation, temperature module acquisition the body's physiological parameters, these signal conditioning circuits for filter and amplifier, LPC2292 comes with A/D converter will transfer over from analog signals into digital signals, the last of the human body through the LCD displays the parameter index.

2.1 ARM system module

ARM system is the system's control center, the main completed operations, control, management, and so on, is the core module of the system.

The system uses the ARM 7 LPC2292 series chip, he is based on a support real-time simulation and keep track of 16/32-bit CPU with 256 kb of embedded FLASH memory and high speed. 128-bit wide memory interface and unique acceleration enables 2-digit code to maximum clock rate. On the code size is strictly controlled by the application can use the 16-bit Thumb mode will reduce the code size is more than 30 per cent, while the performance loss is small. Because of the 144 feet LPC2292 encapsulation, extremely low power consumption, more 32-bit timer, 8-channel 10-bit ADC, 2-channel PWM channels and up to nine external interrupt make them particularly suitable for medical systems, automotive, industrial control and fault-tolerant maintenance bus.

2.2 LCD display module

LCD display module mainly completed data display and output data and display data synchronization capabilities.

Because there is no LCD controller LPC2292 function modules, if you choose LCD internal no LCD controller, then, to make the CPU can be controlled on the LCD, you must design a LCD control circuit. Therefore the system selection comes with controller HLM6323 LCD. He is a 5-inch pseudo color LCD, 320 × 240 pixels, each dot matrix requires a three-colour RGB data, each color requires a 1 byte of data representation. While the design requirements need continuous watch the map image, based on standard 25 frames per second required image, then you need at least per second data transfer to 25 × 8 × 320 × 240 = 15 360 000-bit data, optional serial transmission, you need 4.6 Mb/s serial transmission speeds, but unfortunately, there is no one serial standard transmission is greater than the speed, therefore, will need to choose a parallel data transfer.

2.3 alarm module

When measured in physiological parameters, such as ECG, blood pressure, oxygen saturation, temperature exceeds a preset normal value, the resulting alarm to remind patients quickly for treatment or health care professionals need for emergency measures.

2.4 FLASH data memory and USB interface

In order to ensure that real-time data save, and extract to design this module.

The system selects NAND08GW3D2 series memory chip. Due to the different storage density device PIN, so the system can not be altered in the circuit of upgraded to high-capacity storage devices. Via the USB device interface chip ISP1161A1 extended out a USB device interface. Through the USB interface, you can implement the monitoring system records the data on a PC, the PC or you can download a program through the interface to LPC2292 processor memory.

2.5 system power supply

Power system design is a key component in the design of the entire system, a stable, have a certain power of power supply and reasonable power management is essential.

This system has the following power: CPU core digital and analog power supply voltage + 1.8 V, CPU i/o port digital and analog power supply voltage + 3.3 V, bus isolated power supply, LCD driver power supply, inverter power supply for backlight LCD, other peripheral power supply voltage + 5 V power supply, etc.

3 software design

This system of software design including A

RM of application development and μ C/O S-Ⅱ OS porting 2 basic parts. The main ARM of applications include LCD display program, FLASH save program, USB communication procedures, the keyboard, scanner, A/D and alarm program. C/O μ S-Ⅱ OS is coordinating the tasks of the program LPC2292 management and scheduling. The entire system software flowchart shown in Figure 3.

3.1 LCD driver software design ideas

LCD driver software is a complete data for final output shows that its main software processes data transceiver, LCD on press read, LCD scanning, etc.

Data transceiver for complete data and CPU, LCD flat panel monitor for data transmission, the CPU through the LCD driver chips to transfer data, and the LCD to CPU return response data. In order to enhance the readability of the man-machine interface, the LCD on a few keys, the key reaction should be sent to the CPU, the appropriate response and you can press the key on the LCD display interface settings and other system parameters. LCD scan is to ensure that the display does not appear obvious gaps, do not appear in the video, the video phenomenon appears to be accurate at the time of the error response. One of the key design didn't give each press to use a hardware interrupt, because in this system, a LCD display driver task priorities within an application is the highest, press the uniform use of a hardware interrupt, then use the software on the key to a software interrupt, identify software priority; another reason more because of the press, not enough hardware interrupt set to press the break, if set to break extended, in addition to hardware scaling, but also a software extension that will waste a lot of resources.

This design, LCD drivers need to write two files, one of which is a C language file and the other is a C language header files.

C language file is the communication interface and Protocol file, needs and other modules for data exchange. And header files is to design some basic parameters, LCD in system operation, these parameters will remain basically unchanged.

3.2 USB communication software design ideas

This system design USB communication software interrupt response to achieve that aim is the CPU does not have a USB device or a USB device is not required, you can do other work, save the resources of the CPU and operating system.

It helps to protect the CPU.

3.3 FLASH reads and writes software design ideas

The entire program files including chip erase, chip for write and read, data effectiveness, etc.

Erase to memory to be able to reuse rather than replace the chip; chip writes and reads the entire file centre responsible for storage of data write, at the appropriate time to read the data; effectiveness is to ensure that data is correct, error alert.

This design, storage, there are three memory address entry, all data will need to go through these three address entry, therefore, must ensure that the three address entry at all times and other address, address cross-cutting.

3.4 μ C/O S-Ⅱ operating system of the transplantations

C/O μ S-Ⅱ real-time operating system is a portable, can be cured, you can crop and deprivable multi-task real-time kernel (RTOS), suitable for a variety of microprocessors and microcontrollers.

Its performance comparable to a variety of foot commercial core, in some ways better performance. All code is written in ANSI c, it has good portability.

C/O μ S-Ⅱ, unlike other real-time operating system, he provides to the user is a standard API functions, program developers use API functions provided by the operating system for application development.

To μ C/O S-Ⅱ kernel on application development, you need to program developers in the real time kernel based on building your own real-time operating system. First, the C/O μ S-Ⅱ portable to your own hardware target Board, write out the appropriate driver and the graphical user interface; in these interfaces function above, plus your own application, constitutes the embedded software.

C/O μ S-Ⅱ is a condition of the transplantations: processor C compiler can generate reentrant-code; processor support, and a scheduled interruption; c language can be on, off; processors support a certain number of data storage hardware stack; processors have the stack pointer and other CPU storage content to read, and saved to the stack or in memory of the directive, these five requirements.

Philips company LPC2292 chip and the C compiler ADS1.2 together can meet above five conditions, so the design is fully portable operating system, to improve the functionality of the system.

C/O μ S-Ⅱ software architecture as shown in Figure 4:

Although the C/O μ S-Ⅱ most source code is written in c language, but complete and the processor concerned some code, or must be implemented in Assembly language.

Register for reading and writing only through the store and load the Assembly language instruction.

Transplantation μ S-C/O Ⅱ to a new architecture requires the following three files to modify:

(1), c language header files OS-CPU.H;

(2) C language source file OS-CPU.C;

(3) to compile the source file program OS-CPU-A.ASM.

4 closing

The human physiological parameters monitoring system based on ARM7 microprocessor hardware platform implementation, using the current popular μ C/O S-Ⅱ real-time multi-tasking operating systems, real-time detection of user of ECG, blood pressure, oxygen saturation

And temperature, and can be data analysis, when an exception occurs, it can automatically alert the user to receive timely treatment. The system scalability is high, you can direct the system to scale with GPS, GPRS, CDMA capabilities of the remote human physiological parameter monitor.