The blood pressure of automatic monitoring system design principles

0 introduction

Currently, the hospital is using automatic blood pressure monitor system mostly imported equipment, expensive, high cost of medical treatment.

This article discusses the system cheap, measurement accuracy, has its unique characteristics, with high practical value.

1 system function and composition of the

The system consists of a PC for data reception and data management, with each room individually using automatic blood pressure monitor (in automatic blood pressure monitor and control the internal installation of single-chip Board converted), constitute the complete and automatic blood pressure monitor system.

As shown in Figure 1.

Management PC settings, nurses ' station on PC can be set using the ward's blood pressure monitor startup and measurement of time, and press set time to control blood pressure monitor, blood pressure monitor then receive back of measurement data; eventually the ward 24 hours back data drawn graphics or form for medical reference.

The market can do automatic measurement of blood pressure monitor, but you can only complete stand-alone measurement and a small amount of data storage, unmanned operation cannot be completed at the time of the scheduled start and automatic measurements and measurement data communication transmission function. Automatic blood pressure monitor for design, is equipped with automatic blood pressure monitor internal MCU control plate for receiving PC machine instructions, directives started automatically, measurement, and from automatic sphygmomanometer LCD screen sampling measurement signal, after analyses, decoding, and finally get the measurement data and transfer to the PC for storage, statistics and analysis.

2 automatic sphygmomanometer LCD works

Japan precision automatic blood pressure monitor LCD consists of seven digital tube and 1 sign bit, one of six eight-segment led displays high-voltage, low voltage and pulse number, 1-bit small digital works to display measurements; 1 sign bit displays 4 types of symbols, as reflected in four different working state.

The test observations and logical analysis found that each LCD paragraph digital tube consists of two signal pin control, the sign bit is 1 signal pin, 1 x synchronous signal pins, as signal synchronization benchmark. See Figure 2. LCD signal pin timing relationships as shown in Figure 3.

LCD pin of pulse signal every four synchronization signals up to 1 signal cycle.

In 1 signal cycle can take control of the digital control of four fields, these four fields in the time series of control on the use of the small way; sign bit only show four different symbols, so just one signal pins. In each pin of periodic signals, there are four pulse and synchronous signal pulses, each pulse corresponding control 1 field, when the location is pulse time, the corresponding field will be lit. In this way, four different location pulse waveform to be digital tube 4 different fields (such as a, b, c, d). Therefore an eight digital control only needs 2 signal pins, as in Figure 3 pins 1, 2, shown in waveform as number 3 (see Figure 2) of the pulse signal waveform. 3-chip hardware design

Microcomputer control panel work need automatic blood pressure monitor workflows.

Hardware circuit shall meet the following features:

SCM-a) by two i/o ports send control signals, complete startup and measuring blood pressure cuff.

B) plastic and level conversion.

Microcontroller from sphygmomanometer LCD signal pins on sampling of signal level and microcontroller I/O interface level consistently, and remove the PIN signal on the rising and falling edge of serrations interference, through analog voltage comparator implementation of plastic and level conversion function.

C) signal sampling.

To obtain digital LCD display, 16-pin signal sampling, that is to occupy the microcontroller 16 ports, in order that the Board cannot be placed inside the sphygmomanometer, minimize the circuit board, reducing the footprint microcontroller input channel, 16-pin signal after 2 eight selected a simulation data selector into 2-channel output signal, so you only need to use single chip 2 x I/O ports, three I/O ports as eight selected a simulation data picker control signal decoding, with software scanning method to complete the PIN signal sampling, which significantly reduce the I/O port is in use.

D) and PC communication.

To construct a RS-232 serial communication ports, using a single-chip 3 i/o port and 1 slice IC MAX232.

E) SCM selection.

Comprehensive analysis, selection on with 10 I/O port of SCM meets system requirements. As the signal waveform shaping to fit the needs of single-chip level, requiring multiple analog voltage comparator. Because PIC16C622 MCU 13 I/O ports, internal also has a comparison module, take full advantage of the features of this not only eliminates the more pieces the comparer integrated chip and its I/O ports to meet system requirements. Hardware circuit diagram shown in Figure 4.

4-chip-chip design of the software to accomplish, one is to receive the management of computer instructions, press set time to turn on the power, start the sphygmomanometer is measured; the second is to monitor the whole measuring process.

This not only requires the appropriate hardware circuit, also need software to filter out interference signals, and in the correct sequence, each digital tube pin signal and the sign bit signal from the corresponding pin out, control the synchronization signals with different pin signal of correspondence, use software scan method, use the same digital tube with 2 pin signals together, after analyses, decoding final measurement result. Finally, to complete single-chip and PC communications, the measurement results to management. The main program block diagram as shown in Figure 5.

5 procedures for debugging

Program debugging difficult is how to press

According to the LCD pin signals correctly display time-series data accurately and check-out, not only with hardware circuit, and observe the LCD pin signal timing and the need to repeatedly test and measurement, adjustment software parameters to identify the exact time series data, completely remove the display number of waveform data, and then through the summary of the waveform data, the correct decoding of measurement data. Finally, single-chip and PC communication, you need accurate fit to complete the data transfer.

6 closing

Since the current hospital use automatic blood pressure monitor system mostly imported equipment, expensive, high cost, thus doctor than automatic ECG monitor, automatic blood pressure monitor is far from being universal.

This article discusses automatic blood pressure monitor system is a PC for data reception and data management, design ideas for unique, system structure is simple, and easy to use, compared with similar equipment, cost-effective, accurate measurement, has a high utility value.