In recent years, wearable devices have become more and more concerned in the health field, from the original smart bracelets, pedometers to smart watches, motion monitoring, smart glasses, heart rate oxygen detectors, smart hearing aids, etc. The form of wearable device products already covers almost all possible forms. At the same time, the health monitoring function of wearable devices has also expanded from the initial step counting and blood pressure monitoring to blood sugar, heart rate, pulse, weight calculation, hearing aids, etc. Many well-known brands have also launched health monitoring directions for wearable devices. Various solutions to actively play the role of wearable devices in mobile healthcare.
The following small series is simple to take a look at everyone, at this stage several popular wearable devices in the health monitoring solutions.
1, Freescale MMA9553L step counter sensor
MMA9553L block diagram
The MMA9553L is a countertop sensor from Freescale. You may have seen the MMA955xL. What does it have to do with the MMA9553L? Simply speaking, the MMA955xL is a generic term that includes the MMA9550L, MMA9551L, MMA9553L, and MMA9559L. Model, in fact, these four sensors are the same in hardware. It is mainly composed of ColdFire core, analog front end, Flash, IIC and SPI interface.
The difference is that the internal firmware is different. Firmware is already solidified in the chip when the chip is shipped. Different firmware has different functions. The MMA9553L introduced here is mainly used as a pedometer function.
Customers often ask the difference between MMA9553 and MMA9555. From the above figure, it can be seen that the MMA9555 has more Six-DirecTIon detection and GPIO Input/Output functions than the MMA9553. The other features are the same.
The MMA9553L and the MCU can communicate via the IIC interface or the SPI interface, so the first prerequisite for using the MMA9553L is to tune the MCU's IIC or SPI. This sensor can be operated after the interface is tuned.
2, TI blood glucose detector with MSP430 microcontroller as the core
Based on the MSP430 microcontroller, Texas Instruments (TI) designed a portable wearable blood glucose meter for test sensors through glucose oxidase electrodes.
The program is divided into three parts. The first is the blood glucose measuring circuit. When blood is dropped into the electrodes at both ends of the enzyme electrode, free electrons are generated. Since there is an excitation voltage across the electrode, an directional current flows through the electrode. The excitation voltage uses the ADC module, and the A/D conversion module measures the voltage, so the directional current needs to be converted into a voltage and a certain amplification is performed.
Followed by the temperature detection circuit, because the blood glucose test uses bioelectrochemical reactions, the important factor affecting the reaction is temperature. Glucose oxidase activity is different at different temperatures. Even for blood of the same blood glucose concentration, the same excitation voltage is used, and the magnitude of the current generated by oxidation of glucose oxidase is different at different temperatures. Therefore, it is necessary to compensate according to the temperature to obtain the correct blood glucose concentration value. When the temperature is too high or too low, the glucose oxidase will completely lose its activity. At this time, the blood glucose meter needs to give an alarm, prompting the user that the meter can not operate at this temperature, and avoiding the wrong detection value.
The specific temperature test circuit is as follows:
Finally, the data storage circuit, the system can store up to 1000 historical data, each historical data needs 8B to save, the data contains two information of blood glucose concentration and test date, thus requiring 8000B of storage space. The 24LC64 is an E2 PROM chip produced by Microchip, which can store 8KB. Therefore, it is enough to select a 24LC64 chip.
Starting from low power consumption and high precision, Texas Instruments' blood glucose testing instrument is designed with the MSP430 series as its core. It can quickly measure blood glucose concentration and is very convenient for users to read measurement data.
3, Nordic nRF52832 low-power Bluetooth dynamic heart rate real-time monitoring
In June 2015, Nordic introduced the nRF52832, the first product of its next-generation nRF52 series of ultra-low power wireless solutions, and redefines single-chip Bluetooth products.
nRF52832 comes with the class's first 64MHz ARM® Cortex®-M4F processor, 512kB flash and 64kB RAM, best-in-class ultra-high performance, ultra-low-power multi-protocol Bluetooth intelligence, ANTTM, proprietary with -96dB RX sensitivity 2.4GHz radio, 5.5mA peak RX/TX current, and an on-chip RF balun (RF Balun). The unique fully automated power management system also allows designers to easily achieve optimal power consumption. The nRF52832 is available in an advanced 55nm process including 6 x 6mm QFN and micro 3.0 x 3.2mm CSP package options.
Compared with the nRF51 series, nRF52832 is the biggest highlight of power consumption reduction and performance improvement. The nRF51 series consumes about 8.3mA to 10mA, while the nRF52832 has a peak power consumption of 5.5mA.
Nordic's nRF52832 SoC features the best low-power Bluetooth performance, as well as large memory and storage space, making it ideal for next-generation wristband platforms, and the SoC's powerful hardware floating-point arithmetic unit helps with dynamic heart rate and motion. The recognition accuracy is improved, and its ultra-low power consumption helps achieve longer standby times.
4. Texas Instruments (TI) has a body composition measurement that supports a BLE-connected weight scale
Program description
This reference design is suitable for a full range of weight scale terminals (with body composition function) using TI signal chains, power supplies and connection components. With TI's AFE4300 scale/body composition AFE, you can accelerate the design of your scale or quickly add body composition measurement to your existing platform. The reference design also includes a full BLE connectivity design for easy connection to BLE-enabled smartphones, tablets, and more
Function and characteristics
1. Simultaneous bioelectrical impedance body composition measurement and body weight measurement using AFE4300
2. The MSP430F5528 microcontroller is used to retain calibration data and calculate weight, TBW, ECW, and body composition analysis.
3, using the BLE module connection of TI CC2541
4. The design has been tested and provides everything needed to complete the design (including schematics, layouts, and Gerber files and BOM).
to sum up
Nowadays, the market for wearable devices is very promising, and it can fundamentally bring the latest cutting-edge technology to improve the health of human beings in the mobile medical field. Wearables, especially in the medical field, have been favored by consumers in recent years, and major technology giants are actively deploying wearable medical fields through acquisitions or financing, and releasing health care wearable devices that meet market needs. Expanding the mobile medical market share and making an indelible contribution to the development of the medical electronics industry.
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