A complete solution for portable electronic doctor system, portable medical care is not a problem

Market demand analysis

　　With the continuous improvement of living standards and the increase in the proportion of urban aging, people pay more and more attention to their personal physical health and medical care. In addition, with the continuous advancement of national medical reform in recent years, the home use of medical testing equipment has gradually become a trend.

　 　However, the medical testing equipment currently available on the market is expensive and not affordable for ordinary people. Moreover, they are bulky and inconvenient to carry, which is not conducive to popularization and family promotion. This design makes full use of the CapSense touch sensor technology of the Cypress chip and its embedded high-performance MCU characteristics, as well as high-precision AD and rich on-chip digital-analog mixed programmable peripherals. In this way, only a small number of peripheral devices are needed to achieve real-time measurement and storage of human body temperature, pulse, high blood pressure and low blood pressure. Thus, a portable electronic doctor design scheme that integrates practicality and multi-functions is realized.

　　From the above analysis, it can be seen that this design has huge market demand and development space.

　　Overall design

　　The overall architecture of this design is shown below:

　　Figure 1. Overall architecture diagram

　　As the main control board, the CY8CKIT-003 PSoC 3 FirstTouch Starter Kit development board provides a wealth of on-chip peripheral resources and on-board digital-analog mixed signal acquisition, transmission and communication modules, which can achieve the following functions with the expansion of a small number of peripheral devices:

　　1. Pulse measurement function

　　2. Blood pressure measurement function

　　3. Body temperature measurement function

　　4. Watch functions

　　5. Data transmission and data collection functions

　　The data can be transmitted to the PC via a USB interface or wireless transmission, and then compared and analyzed with a pre-designed related database to obtain the corresponding doctor's prescription or suggestion.

　　The results of the first four functions can be intuitively displayed on the LCD display under the control of the function buttons, realizing real-time data collection and display. It is expected that the final product of the entire system will be simple to operate, powerful and practical, and have a friendly human-machine interface.

　　Key module design

　　Pulse measurement

　 　According to the division of functional modules, the system hardware structure block diagram is shown in Figure 2, which includes the following parts: ① Sensor: converts the pulse beating signal into the corresponding electrical pulse signal. ② Amplification and shaping circuit: amplifies the weak signal of the sensor and shapes it to remove stray signals. ③ Frequency multiplier: increases the frequency of the pulse signal obtained after shaping. For example, if the signal frequency obtained by the sensor within 30 seconds is doubled, the corresponding number of pulses per minute can be obtained, thereby shortening the measurement time. ④ Reference time generation circuit: generates a short-time control signal to control the measurement time. ⑤ Control circuit: used to ensure that the doubled pulse is sent to the counting decoding display circuit under the control of the reference time. ⑥ Counting decoding display circuit: used to read the pulse number and display it on the LCD in the form of a decimal number.

　　In the above measurement process, since the pulse frequency is doubled, the timing time is also shortened by 2 times (30 seconds), but the digital display is the number of pulse beats per minute. The error measured by this scheme is ±2 times/min. The shorter the measurement time, the greater the error.

　　Figure 2. Pulse measurement hardware block diagram

　　Blood pressure measurement

　　The block diagram of the blood pressure measurement module is as follows

　　Figure 3: Blood pressure measurement module implementation framework

　 　The process of measuring blood pressure once is as follows: press the activation key ADC output to control the air pump to inflate to 200 mmHg, and then slowly deflate at a rate of about 5 mmHg per second. The output signal of the pressure sensor is converted into a single-ended signal after the differential amplifier, and sent to the MCU ADC to monitor the DC component, and the other way is sent to the 0.8 Hz second-order high-pass filter to filter out the DC component; the AC component is amplified 200 times and input to the 38 Hz second-order low-pass filter to remove the high-frequency noise and power frequency interference of the power supply and the friction between the skin and the cuff, and the signal is maintained between 0 and 5 V. The filtered AC component is sent to the blood pressure pulse trigger and then triggers the MCU ADC to work, and the other way is sent to the MCU ADC to calculate the amplitude. First find the maximum amplitude value Amax, and then find the transient position with an amplitude of 0.5Amax in the front, which corresponds to the blood pressure DC component, which is the systolic pressure, and find the transient position with an amplitude of 0.8Amax in the back, which corresponds to the blood pressure DC component, which is the diastolic pressure. The calculated systolic and diastolic pressure results are output to the LCD driver for display. The blood pressure signal and the locations of systolic and diastolic pressures are shown in FIG4 .

　　Figure 4. Blood pressure DC signal and systolic and diastolic blood pressure positions

Temperature measurement

　 　Body temperature measurement can be easily achieved using the temperature sensor and internal ADC circuit of the CY8CKIT-003 PSoC 3 FirstTouch Starter Kit development board. The figure below is the circuit diagram of the temperature sensor design of the CY8CKIT-003 PSoC 3 FirstTouch Starter Kit development board.

　　Figure 5. PSoC 3 development board onboard temperature sensor and body temperature measurement circuit

　　Watch features

　 　Since the core chip CY8C3866AXI-040 of the CY8CKIT-003 PSoC 3 FirstTouch Starter Kit does not have its own RTC module circuit, we have expanded it with a Philips PCF8563 real-time clock chip, which uses the I2C bus to achieve control and real-time clock data transmission. It has year, month, day, hour, minute, second, setting and timing functions, and can independently assume all the functions of a watch. In addition, the CY8C3866AXI-040 chip integrated I2C bus interface can also be conveniently used for data communication.

　　The PCF8563 real-time clock circuit is as follows:

　　Figure 6. PCF8563 clock chip circuit schematic

　　System software design

　　Software design is the key to realize the function of this design, but Cypress provides a series of software development tools:

　　a. PSoC Creator 1.0

　　b. PSoC Programmer 3.10

　　c. Keil C51 Compiler (Cypress edition)

　　d. GNU GCC Compiler (for PSoC 5 development)

　　e. PSoC 3 FirstTouch Starter Kit example projects and documentation

　　It is convenient for us to build the software platform for this design, especially the PSoC designer 5.0 IDE integrated software development environment of Cypress, which can automatically generate driver functions for all on-chip peripherals according to the circuit, making it convenient for us users to operate and control the on-chip peripherals.

　　Considering the large number of peripheral modules and multiple control algorithms used in this design, C language is used for software design, which makes programming easier. The software design flow chart of the entire system is as follows:

　　Figure 7. Software flow chart of portable electronic doctor system