Difference between revisions of "S17: Smart Health Gear"

Revision as of 04:51, 25 May 2017

Grading Criteria

Project Title

Smart Health Gear

Abstract

Smart Health Gear is a wearable device which will help in monitoring various aspects of a person's health like heart rate, foot steps count and body temperature. It will come with a compatible android application which will notify the user on completion of daily activities and log all the data from the Smart Health Gear to provide a history chart.

Objectives & Introduction

Show list of your objectives. This section includes the high level details of your project. You can write about the various sensors or peripherals you used to get your project completed.

The objectives are as follows:

1. To be able to calculate and continuously monitor the heart rate
2. To be able to calculate the oxygen level in blood
3. To be able to calculate the body temperature
4. To be able to calculate the step count of the person
5. To be able to view all the vital details on a wearable device having LCD
6. To be able to view the same details on an Android app

Team Members & Responsibilities

• Aniket Dali
• Jean Mary
• Manoj Ramesh Rao
• Neha Biradar
• Sushma Macha

Schedule

Show a simple table or figures that show your scheduled as planned before you started working on the project. Then in another table column, write down the actual schedule so that readers can see the planned vs. actual goals. The point of the schedule is for readers to assess how to pace themselves if they are doing a similar project.

Parts List & Cost

• Total Cost: 153.79$

Design & Implementation

The design section can go over your hardware and software design. Organize this section using sub-sections that go over your design and implementation.

Printed Circuit Board

The PCB design was one of the challenging part of this project. The PCB design was created in Autodesk Eagle v8.1.0. Before proceeding with the schematic, we had decided to design a PCB that matches with the size of the SJ one board such that it could be mounted over it. Considering designing a wearable device, we had to keep in mind the form factor of the PCB. Initially we designed a PCB which turned out to be four-layer PCB including the blood pressure monitoring subsystem. However due to budget constraints we had to give up the blood pressure system as printing the same required a licensed version of Eagle.

Before starting the PCB schematic design, we decided on the location of sensors as it was vital for a wearable health monitoring device with a LCD display facing the user. Since surface mount soldering was not an option we decided to design the schematic with through hole connections. Another challenging part for our design was the libraries needed for schematic design. Since we didn’t have libraries for heart rate sensors, we had to design by creating it from scratch. However, we had some libraries from sparkfun, Eagle and Adafruit, the entire process took most of our time.

The first step in PCB design is to import all the libraries of the components that we would be using and create a schematic using the same. We made use of the Dimension tool in Eagle to match the PCB size with that of the SJ one board. We created the schematic by placing the required components and wiring them. The tutorial on Sparkfun website was very helpful in designing the same. It was very important for to ensure that all connections are verified properly before it gets printed. This was done using “DRC” Design Rule Check in Eagle which would show if any consistent errors existed.

EAGLE Schematic

PCB schematic

EAGLE Connector List

Once the schematic is created that can be easily converted to Board Layout using the Generate/Switch to board option in Eagle. But this would create the board by randomly placing the parts at different locations. Since we had to have an LCD mount over the PCB as well as match the 17x2 connectors with that of SJ one board we created the design accordingly. After ensuring that everything was in place we placed order for the PCB and verified the same again using a multi-meter if all the connections were correct.

PCB board layout

Hardware Design

Discuss your hardware design here. Show detailed schematics, and the interface here.

System block diagram

Heart Rate Sensor

Temperature Sensor

LCD

The LCD interface is used to display the information collected from all the sensors to the user. ILI9340 supports a TFT liquid crystal display with a resolution of 240RGB*320 dots. It supports full color, 8-color display mode and sleep mode as well as precise power control by software. Moving pictures can be independently displayed in an address window such that only that window displays moving picture even if the rest of space displays static data.

SPI0 peripheral is initialized as master and the LCD is interfaced as slave. LCD is initialized by sending commands to set the power, frame rate, pixel depth etc., The display is activated by giving vcc to its LED input. The commands are sent along with parameters via SPI in the pre-defined sequence in order to perform actions like setting the row and column index to position the pixel appropriately. The data and commands are distinguished by d/cx input pin which can be written 1 for data and 0 for command.

To display characters or lines or any shapes we need to fill up the screen pixel by pixel by positioning the pixels in appropriate location using the row set and column set commands. The commands and its parameters are sent to LCD via SPI interface and are then followed by the data i.e., the pixel color. There are two screens – The default screen will display the Time Stamp and the next screen will display the sensor data. These two screens are swapped either after timeout or after a button press. A timer is initialized to count every micro second and after counting 300 times the timer gives a binary semaphore which is captured a task which swaps the screens. The LCD is interfaced to two switches using two GPIO pins. One switch is used to power off and power on the LCD and the other one is used to navigate between the two screens.

There are two tasks running, Display Task, Button Task at equal priority. The Display Task is waiting for a screen_change semaphore which is given by timer or button press. It checks for any update to be made in the clock screen i.e., if any of sec, min, hour, day, month or year is changed if so it updates the same. If and when the semaphore is given the task takes it and changes the screen based on the value of a variable which represents the current screen. Button Task is waiting on a sensor_button semaphore which is released by an interrupt triggered by the button press.

HC-05 Bluetooth Module

HC-05 module is an easy to use Bluetooth SPP (Serial Port Protocol) module, designed for transparent wireless serial connection setup. Serial port Bluetooth module is fully qualified Bluetooth V2.0+EDR (Enhanced Data Rate) 3Mbps Modulation with complete 2.4GHz radio transceiver and baseband. It uses CSR Bluecore 04-External single chip Bluetooth system with CMOS technology and with AFH(Adaptive Frequency Hopping Feature). It has the footprint as small as 12.7mmx27mm.

Hardware Features

• Typical -80dBm sensitivity
• Up to +4dBm RF transmit power
• Low Power 1.8V Operation, 1.8 to 3.6V I/O
• PIO control
• UART interface with programmable baud rate
• With integrated antenna
• With edge connector

Software Features

• Default Baud rate: 38400, Data bits:8, Stop bit:1,Parity:No parity, Data control: has.

Supported baud rate: 9600,19200,38400,57600,115200,230400,460800.

• Given a rising pulse in PIO0, device will be disconnected.
• Status instruction port PIO1: low-disconnected, high-connected;
• PIO10 and PIO11 can be connected to red and blue led separately. When master and slave

are paired, red and blue led blinks 1time/2s in interval, while disconnected only blue led blinks 2times/s.

• Auto-connect to the last device on power as default.
• Permit pairing device to connect as default.
• Auto-pairing PINCODE:"1234" as default
• Auto-reconnect in 30 min when disconnected as a result of beyond the range of connection.

Software Design

Show your software design. For example, if you are designing an MP3 Player, show the tasks that you are using, and what they are doing at a high level. Do not show the details of the code. For example, do not show exact code, but you may show psuedocode and fragments of code. Keep in mind that you are showing DESIGN of your software, not the inner workings of it.

Heart rate sensor:

• The heart rate (bpm) is calculated by sensing the photoplethysmograph signal from the Pulse and Oximeter Sensor. By connecting the sensor on I2C interface we get the raw values and collect about 100 samples every second.
• Initialize the sensor settings like enabling HR mode, SpO2 configuration, interrupt 1 and interrupt 2, FIFO write and read pointer, FIFO configuration by writing appropriate values into the registers as specified in the datasheet.
• The raw values contain noise as well so it is eliminated by finding derivative of the signal. For this purpose, we find the slope of the signal which would be series of either positive or negative numbers.
• To this derivative signal, a hamming window is applied to smoothen out all edges and the signal is like a sine wave.

Algorithm Pseudocode:

• Read values from FIFO register whenever interrupt occurs.
• Continuously take samples from MAX30102. The heart rate and SpO2 are calculated for every 1 second.
• Eliminate the first 100 samples from the register and calculate for every 500 samples by sliding the frame as samples occur.
• Find moving average of the sample raw values i.e slope calculation
• Apply hamming window to the signal with window size as 5.
• Find peak height, peak distance and the maximum number of peaks.
• Find at most MAX_NUM peaks above MIN_HEIGHT separated by at least MIN_DISTANCE
• If number of peaks < 2, find peak interval sum.
• Find the peak interval sum = time of last peak – time of next peak.
• Based on the sampling rate, calculate the heart rate 6000/ peak interval sum and loop back to finding peak.
• For SpO2 calculation, we need to assess DC and AC value of ir and red PPG.
• Find maximum between two peaks and use ratio between AC component of Ir & Red and DC component of Ir & Red for SPO2.
• The accurate SPO2 is precalculated and save in uch_spo2_table[] per each ratio
• Ratio = -45.060*n_ratio_average* n_ratio_average/10000 + 30.354 *n_ratio_average/100 + 94.845
• Match the ratio as per the the values in table to get the correct SPO2 value.

Implementation

This section includes implementation, but again, not the details, just the high level. For example, you can list the steps it takes to communicate over a sensor, or the steps needed to write a page of memory onto SPI Flash. You can include sub-sections for each of your component implementation.

Testing & Technical Challenges

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Include sub-sections that list out a problem and solution, such as:

My Issue #1

Discuss the issue and resolution.

Conclusion

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Project Video

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Project Source Code

• Sourceforge Source Code Link

References

Acknowledgement

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References Used

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Appendix

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