duō cān shù jiān hù yí
Multi-Parameter Weight Monitor is able to provide important information about the patient for the clinical diagnosis of the medical science, and it can detect in real time the human body's electrocardiographic signals, heart rate, oxygen saturation and other important parameters such as the blood pressure, respiratory rate and body temperature, and realize the supervision and alarm of each parameter, blood pressure, respiratory rate and body temperature and other important parameters, to realize the supervision and alarm of each parameter. Information storage and transmission, is an important equipment to monitor the patient, but the current domestic monitor is generally a single function, mostly CRT display, large volume, mobile inconvenience, there are shortcomings.The portable microcomputer parameters physiological monitor, detection parameters, compact design, compact size, easy to carry, can be used in the ward, can also be used for outdoor, can be timed, continuous, long time to detect the patient's important life characteristics of the parameter, it is in the protection of the patient's life safety has an important clinical use value.
2 Working Principle 2.1 1.System Working PrinciplePortable microcomputer multi-parameter physiological monitor host consists of two 16-bit microcontroller 80C196.
The system converts biomedical signals into electrical signals through the signal detection and pre-processing module, and performs pre-processing such as interference suppression, signal filtering and amplification. Then, it samples, quantizes, and calculates and analyzes each parameter through the data extraction and processing module, compares the result with the set threshold, supervises and alarms, and stores the resultant data in real time into RAM and can be transmitted in real time to a PC, where the value of each parameter can be displayed in real time.
2.2 2. System StructureThe system block diagram is shown in Figure 1. The monitor consists of two microcontrollers to form a dual-CPU system.
MCU 1 completes the signal detection, processing, data storage of body temperature, ECG waveforms, and pulse shape, and displays and alarms the waveforms and parameters at regular intervals through the LCD display.
MCU 2 to undertake the time-consuming measurement of blood pressure and oxygen saturation detection, so that it does not affect the normal work of the entire system, but also to undertake the heart rate, respiratory rate determination.
The information exchange between the two microcontrollers is carried out through an 8-bit parallel port, and the communication control is realized by two I/O ports. Specifically, the P1 port, with two high-speed input and output I/O ports (HIS.0, HSO.0), is used as a data transfer between the two microcontrollers. This continuous way between the two machines belongs to the loosely coupled multiprocessor system (Ref. 8), which is relatively simple in hardware implementation, and only needs to design the necessary communication protocols, data transmission methods, etc. for its communication method during software programming.
2.3 3. System Hardware Design(1) The system uses EEPROM 28C64 as the program memory; a piece of non-volatile static memory (NASRAM) is used as the data memory.NASRAM has the advantages of static memory, and at the same time, it has the characteristics of non-volatility. The feature of non-volatility means that the memory chip is able to save all the data correctly and without error for up to 10 years in case of power loss. The non-volatile features of the chip can be used to realize power-down data protection without providing power-down backup power for the chip.
(2) LCD module
In order to display ECG waveforms, pulse waveforms and other physiological parameters, and the waveform display has sufficient resolution, the system uses a graphical LCD. In order to reduce the size of the instrument, to achieve the system low cost, low power requirements, the choice of monochrome LCD display is particularly suitable for portable monitors.
The display for the Hitachi LMG70520XNGR LCD, the number of dots for the 640 × 200, the point size of 0.22 × 0.30, and its drive power supply for the +5V and 20 ~ 21V, power consumption of only 8mW, to meet the requirements of the system.
In order to control the display of the display, we selected for the display of the display controller SED1330. the chip is used for computer commands and data, and produce the corresponding timing and data control LCD display. The controller comes with RAM, self-management of the display buffer, and the CPU through the 8-bit data parallel transmission, and the display is 4-bit data parallel transmission.
(3) Keyboard Input Module
The system is designed to use interrupt input for the function keys. When any function key is pressed, a keyboard interrupt is generated, and the CPU executes the interrupt program, reads the key code, and performs the corresponding operation; when there is no key pressed, it does not take up the CPU's running time, which improves the CPU's running efficiency.
The keyboard uses two 74LS373 to form a matrix software coding keyboard, the keyboard part is directly hanging on the bus of the microcontroller 1. Does not occupy the microcontroller I / O port line, and do not have to expand the system I / O port for this purpose, can reduce the system power consumption.
By assigning the corresponding I/O address to the keyboard, the key code can be obtained by reading or writing the address. Hardware implementation is simple and software programming is easy.
(4) power supply system
Based on the consideration of low power consumption and easy to carry and use, the system adopts the battery power supply and external ACDC conversion device power supply. The design uses three 1.5V batteries for power supply. The voltage is supplied through a voltage regulator to provide +5V for the system to work. At the same time, the DCDC voltage converter +5V voltage converter to 18 ~ 24V voltage, to provide the LCD display work.
The choice of battery as a power source was based on the following considerations: high output capability, small form factor, standard size, and low price.
(5) peripheral device control
The system peripheral device chip selection signal by the 74LS373 latched address signal, the chip GAL16V8C decoding generated. GAL chip is a programmable logic array, through the programming of its pins, it will be used as a decoder, based on the P4 port high byte 8-bit address for the selection of the chip, which is easy to program, and flexible to use. In addition to being used as a decoder, the system is also used as a switch to control the air pump and air valve in MCU 2.
Through the cluster has been assigned to the air pump or valve I / O port address, write "0" or "1", the output pins OUT1, OUT2 for low or high level. The level will be maintained until the same address again to write "1" or "0", so that you can regularly control the air pump or valve switch.
2.4 4. System software designThe main feature of the system software is that the real-time data as the core, to function independently, modular structure for the software design mode. System development adopts a structured, top-to-bottom module division and bottom-to-top hardware function encapsulation of the software development design method. The system uses C96 language for software system development.
(1) Data Acquisition Program
Data acquisition to the entire system is the most important issue. How to realize data acquisition, to ensure real-time data acquisition, and can be efficient data acquisition, as little time as possible to occupy fewer system resources, for multiple parameters at the same time guardianship, is to ensure that the system processing of real-time important factors.
In the software design, we utilize hardware timers and software timers for timed interruptions to carry out the design of the data acquisition process for multiple channels and sampling points. Due to the slow change of human physiological signals, this method has been used to ensure high-precision, real-time data acquisition.
(2) LCD control
The realization of the system display function, in fact, is the programmed control of the display controller SED1330. SED1330 controller has a system control, display operation, drawing operation, storage operation, etc. **** 15 commands.
When programming the system display module, we use the C96 language to classify and combine the functions of the SED1330's instructions, encapsulate them, and compile a basic display control chart function library. Through the call to the sub-function, it is very convenient to realize the complex human-machine interface program design.
Designed sub-functions are as follows:
lnitCD(); /* Initialize SED1330 */
ClearDispBuffer(); /* Clear the display buffer */
ChooseScreen(screen); /* Choose the display buffer */
SetCsrAbsAddr(addr); /*Set the absolute cursor position*/
SetCsrDir(dir); /*Set the direction of cursor movement*/
PutChar16xy(x,y,data); /*Display the dot matrix as a 16×16 font*/
SetPutPixel (x,y); /* show a point on the display*/
H_line(x1,x2,y,linestyle); /* draw horizontal line*/
V_line(x1,y1,x2,y2); /* draw vertical line*/
lnvert(x1,y1,x2,y2); /* to rectangle area Invert(x1,y1,x2,y2); /* draw vertical lines */
lnvert(x1,y1,x2,y2); /* on rectangular area
Part of the LCD subroutine example is as follows:
# include 80c196.h
# include "data.dat "
# include init.c
# define UP 0x4e
# define DOWN 0x4f
# define LEFT 0x4d
# define RIGHT 0x4c
# define AP 80
# define SA1 0
# define SAD2 0x3e80
# define Max_X 640
# define Max_Y 200
# define ECQ_Y 128
# define PLUSE_Y 50
# define NORMAL ox4f
# define DOT_1 0xaa
# define DOT_2 0x66
unsigned char * m_reg;
unsigned char * pram_reg;
unsigned int_sad;
/************************/
/* var screensvalue is:1 or 2.*/
ChooseScreen(screen)
Unsigned char screen;
{
switch(screen){
case 1:
_sadSAD1;break;
case 2:
_sadSAD2;break;
defaulf:
_sadSAD1;}
}
/*************************/
lnitl_CD()
{
* m_reg0x40; /*SYSTEM SET */
* pram_reg0x34;/P1 CGRAM font dot array(now is:8x16)*/
* pram_reg0x87; /*P2 */
* pram_reg0x07;
* pram_reg80;
* pram_ reg93; /*P5 93 */
* pram_reg200;
* pram_reg80; /*P7 */
* pram_reg0; /*P8 */
* m_reg0x44; /*SetSooll() */
/*set SAD1 */
* pram_reg0x0; /*P1 */
* pram_reg200; /*P3 */
/* set SAD2 */
* pram_reg0x80; /*P4 */
* pram_reg0x3e;
* pram_reg200; /*P6 */
/*set SAD3 */
* pram_reg0x00; /*P7 */
* pram_reg0x7d; /*P8 */
/*set SAD4 */
┆
* m_ reg0xf58; /*Set Display(OFF)*/
/* *pram_reg0; */
* m_reg0x5d; /*SetCsrForm()*/
* pram_reg6;
* pram_reg0x86;
* m_reg0x5a; /*set HDOT SCR*/
* pram_reg0; /*must be clear*/
* m_reg0x4c; /*set csr dis is:RIGHT*/
* m_reg0x5b; /*SetOvlay */
* pram_reg0x1c; /*three graphics display zone*/
* m_reg0x5c; /*SetCGRAM(addr)*/
* pram_reg0xf0; /*turn off the CGAM */
* pram_reg0xf0;
* pram_reg0;
* m_reg0x59; /*SetDisplay(ON)*/
* pram_reg0x16;
ClearDispBuffer();
}
... ...............
The problem to be solved when utilizing an LCD display is to clear graphical discontinuities. The analog waveform is a continuous graph, but the display shows it as discrete dots, which results in breaks along the rapid rise and fall of the waveform.
To do this, we designed a comparison subroutine. When the amplitude difference between two neighboring columns of points is greater than 2, all the points between the two points will be "lit", so that the display of the graphics continuous.
(3) the application of the interrupt system
The realization of the functions of the system, mainly by the interrupt program program. Such as the use of keyboard input interrupt, data acquisition interrupt, dual-computer communication, communication between the upper and lower computer interrupt service. Interrupt service in the whole system software plays an indispensable role.