The realization of the intelligent body fat weighing scheme

I. Overview

as people live more and more attention to the quality of life, the emergence of intelligent body fat can be measured by measuring body fat, body moisture, body weight, and a series of data to provide users with reference. To achieve the goal of testing fitness outcomes or health indicators.

Two. Power supply circuit design

Power circuit design: Powered by four 1.5v fifth battery. The voltage regulator chip provides 3.3v to the MCU, while the MCU pin monitors the battery charge change. In addition, through the chip LM2776 power supply to the human body impedance detection circuit amplifier to power supply.

Three. Weight detection circuit

The change of the voltage is detected by the change of the load cell and the resistance stress. Weighing sensor A module can be measured 50kg, here four modules measured together can measure the weight within 200kg. The sensor module consists of a full bridge circuit, which is transmitted to the MCU through the chip CS1237 to sample the change of the value.

Four. Human body impedance detection circuit

the principle of impedance detection is through the human body through an electric current, because the body of fat is almost non-conductive, and the water in the muscle tissue is easy to conduct electricity, therefore, the body's fat can be measured by the user's bio-resistance and estimated. So four electrodes are placed on the plate to power the body. The voltage flowing out of the human body amplifies the signal through an amplifier, and after ad sampling, the data is transmitted to the MCU via the IIC bus.

Five. LCD data display Circuit

the chip TM1723 is used here to drive the LCD. This is more stable than a single-chip microcomputer to drive the LCD directly. The display relationship for the 4-bit 8 segment is as shown.

Six. MCU system circuit

The main control MCU is St's stm32 single-chip microcomputer series, stm32f103c8t6,stm32 single-chip microcomputer technology mature, community support is good. and the development prospects and the Internet of things industry is very close. Here is an MCU minimum system and includes a download circuit and a debug circuit.

Seven. Data transmission circuit (Bluetooth or WiFi)

the use of the HC-05 Bluetooth module for data transmission, can be connected to the mobile phone Bluetooth, the data transfer to the app record. The app is passed into the cloud to analyze or record data. Or you can use WiFi to upload data directly to the cloud. is a schematic diagram of the Bluetooth module.

Eight. Software design

(to be added)

Nine. Programme summary

Some of the solutions also require sample validation. Now on the market, the intelligent body fat weighing scheme, the hardware form is basically fixed. So a variety of functions can be achieved in software. For example, through the big data analysis of the user for a period of time of body fat, moisture, weight and other data changes, through the algorithm to give users recommend sports fitness programs and healthy diet programs. To achieve one purpose of physical health. Have seen a body fat weighing evaluation analysis report, which Huawei and millet body fat said the highest accuracy, many other fundamental no gap is large. The special body fat in the hospital says that in addition to the feet to contact the electrodes, the hands should also contact two electrodes, which should make the test results more accurate. However, in daily use, one is to take into account the body fat weighing volume, easy to organize and carry. Or the use of only foot contact to the program. I think a product design not only to consider the completion of the function, more importantly, to meet the needs of users. If it's just a developer who thinks or plans a feature that fits his or her product, even if the technology is high, it doesn't necessarily make the user feel comfortable. Therefore, the birth of a consumer-grade product, to do a good job in this market research. Seize the user most want to add features, so that the product will sell well. A plan needs to take into consideration a variety of factors, the gradual change, will become a good solution.

The realization of the intelligent body fat weighing scheme