GPS global positioning technology in medical monitoring unit (1)

Summary

This article on GPS global positioning technology in medical care in the preparation of a GPS, medical monitoring location device which mainly consists of single-chip control module and GPS receiver module of two parts, with high precision, good stability, resistance to decay ability is strong, small power consumption, enables outdoor need care.

1. preface

At present, China has approximately 3 billion needed care care groups, mainly for children and elderly people.

Because of the tensions of modern life rhythm, parents are busy working, children have more free space, often find lost children, were injured; hospital patients such as dementia patients is also lost. How to enable the groups at any time, has become a vast number of caregivers were very interested and eager to solve the problem.

GPS (global positioning system) [1] is the United States from 1970s began developing, which lasted 20 years, the $ 200 billion, fully completed in 1994, with the sea, land and air for Omni-directional real-time 3D navigation and positioning satellite system, the ability to have good performance, high precision, wide application, is free to use, was by far the best navigation system.

As the global positioning system of continuous improvement, hard and software continues to improve, application areas are constantly develop, present throughout the various departments of the national economy, and begin to step down people's daily lives. We use GPS technology used in the preparation of care to meet the positioning device family children, hospital patients, real-time care, so that the work of parents at ease and prevent hospital patients lost to improve patient care in hospitals, extended the scope of activities.

2. the device hardware design and implementation

The medical monitoring device (fig. 1) consists of two major components: MCU control module and GPS receiver module, the module through the serial port the interaction mechanisms for information.

Figure 1 the structure of medical care system

2.1 MCU Module (Figure 2):

By extending the external circuit, realized on the physiological parameters of data acquisition, keyboard operation, physiological parameters LCD display and automatic alarm, etc.

LCD we use G191 LCD module, 192 x 128 dot-matrix, the point size of 0.33 × 0.33mm, dot pitch to 0.04mm, driving power for + 5V and-20V. We use the LCD controller, the controller used SED1335 received from control module of instructions and data, and produce the appropriate timing for the LCD display for control, SED1335 software is powerful, but with data RAM and self-managed display cache so that we can use.

Figure 2 microcontroller circuit module

2.2 GPS receiver module:

From the GPS satellites (space segment) to receive information and real-time data to be sent via the UART serial MCU Module, in the design process, through analysis and comparison, we picked a Taiwan company GR-85 serial HOLUX GPS receiver.

In signal capture and signal accuracy, GR-85 has its unique advantages. Its signal recapture time only need 100ms, the minimum speed update rate can reach 1s.

GR-85 receiver module, a serial communication mode, the data format is defined as follows: 9600b/s, 8 data bits, 1 stop bit, output polarity.

GR-85 supports six NMEA-0183 protocol information: GGA, GLL, GSA, GSV, RMC, VTG. The six types of information are distinguished by the user can receive information types vary, for example in the RMC format in the speed of information in other formats do not. Designers can choose the response message format, the experimental use of RMC format. Table 1-GPS receiver module PIN. Receiver module with single-chip communications mainly through TXA feet.

Table 1 GPS receiver module pin

3. system software design and implementation

GPS receiver status as long as the work is in power will continue to receive and the calculated GPS navigation and position information through a serial port to the micro system.

On GPS information extraction must first clear the frame structure, the data frame is mainly composed of frame, frame tail and frame data. All frames are carriage <CR>和换行符<LF> as frames, identifies the end of a frame. Frame processing, the data is to be judged on the frame header, and then on the desired frame for data extraction. As the data segments within the frame is a comma-separated, so when receiving data in processing is generally the first search "$" ASCII codes to determine whether the frame header, then the frame header to identify the categories, and then again based on the recognition of frame type, and a comma ', ' number to determine the current reading is which parameters and make the appropriate extraction and storage. We use the interrupt method to obtain the GPS data.

In order to keep receiving and processing time and longitude latitude data in memory, we set aside a fixed space.

Which 3BH-5FH used for storing the received time and longitude latitude data, 6BH-7FH used to deposit processing time and longitude latitude data.