This document summarizes a student project to build a heart rate monitoring watch using an infrared sensor, ARM microcontroller, and Raspberry Pi. The system measures heart rate using an infrared sensor board, converts the analog signal to digital with an ADC, transmits data over WiFi, and calculates and displays the BPM on a web client. The goals are to analyze heart conditions for health monitoring, provide alerts for emergencies, and act as a personal health coach using a simple, low-cost device.

1. 105 嵌入式韌體工程師菁英班
Internet of Things
of
Heart Rate Watchdog
Group Members :
劉語文
高世宇
何裕鈞
王建凱
Special thanks for instructions given by 何文吉

2. You care about your health!
You care for your heart!
…Affecting heart rate and
pulse, moreover your health!

3. The ‘Why’ for
the project!
• For any possibilities:
– Analyze heart conditions for personal daily health
maintenance
– Red alert for emergencies
– Remotely observe the health welfare of those you love
– Smart software as personal health coach
– Easy-to-carry heart rate device
– Simple usage and low cost
P.S. Heart disease is the
NO.1 death factor in the world!

4. Sensor
Board
ADC
UARTs WiFi
Web Server
1.TCP socket
2.WebSocket
Heart Rate
Calculation
on PC
LCD
System Structure
Rasbberry Pi 2
ARM MCU
Client

5. Heart Beat
Calculation and Analysis

6. Heart Beat’s Waveform
• Diagram 1 – Animated plotting
• Diagram 2 – Recorded data points with peaks

7. BPM
(Beats per minute)
𝐻𝑒𝑎𝑟𝑡 𝑅𝑎𝑡𝑒 =
N𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝐵𝑒𝑎𝑡𝑠
(𝑇𝑎−𝑇𝑏) (𝑠)
∙
60 (𝑠)
1 (𝑚𝑖𝑛)
= 𝐵𝑒𝑎𝑡𝑠
𝑚𝑖𝑛
𝑇𝑎
(first beat at time 𝑇𝑎)
𝑇𝑏
(last beat at time 𝑇𝑏)

8. ARM MCU
&
Electronics

9. Sensor
Board
ADC
UARTs WiFi
Web Server
1.TCP socket
2.WebSocket
Heart Rate
Calculation
on PC
LCD
Client
Rasbberry Pi 2
ARM MCU
System Structure

10. Infrared Sensor CNY70 Board
Heart
pumps
Heart
relaxes
A. Signal detect B. Current Amp.
C. Volt. Amp.
Blood
thickens
Blood
thins

11. Physical Sensor Board
• Done with OrCAD schematic and Allegro layout

12. Sensor
Board
ADC
UARTs WiFi
Web Server
1.TCP socket
2.WebSocket
Heart Rate
Calculation
on PC
LCD
Client
Rasbberry Pi 2
ARM MCU
System Structure

13. Analog-to-Digital
Converter
ADC converts analog
signal every 20ms.
ADC Process

14. Sensor
Board
ADC
UARTs WiFi
Web Server
1.TCP socket
2.WebSocket
Heart Rate
Calculation
on PC
LCD
Client
Rasbberry Pi 2
ARM MCU
System Structure

15. ADC
Converted data
UART1
UART0
BPM calculation
Data to UARTs
Wifi
Data storage

16. Sensor
Board
ADC
UARTs WiFi
Web Server
1.TCP socket
2.WebSocket
Heart Rate
Calculation
on PC
LCD
Client
Rasbberry Pi 2
ARM MCU
System Structure

17. WiFi Transmittion
By UART0
Original Signal
UART0

18. Internet
Communications

19. Sensor
Board
ADC
UARTs WiFi
Web Server
1.TCP socket
2.WebSocket
Heart Rate
Calculation
on PC
LCD
Client
Rasbberry Pi 2
ARM MCU
System Structure

20. TCP
socket
HTTP
WebSocket
MCU
Server
Client
Internet Comm.
Broadcast
Broadcast
Clients

21. Using WebSocket
Over Polling
Source: http://www.websocket.org/quantum.html

22. WebSocket
Connection
Open
On_message
Close
Build and record connections
Start and transfer data for both
sides of client and server
Disconnect connections and remove records

23. WebSocket
Data Transmitting
HTTP
request
response
WebSocket connecting
Data sent at different times
Server Client
Chopped data 1
Chopped data 2
Chopped data 3

24. Webpage As Client

25. Sensor
Board
ADC
UARTs WiFi
Web Server
1.TCP socket
2.WebSocket
Heart Rate
Calculation
on PC
LCD
Client
Rasbberry Pi 2
ARM MCU
System Structure

26. Graph frame
setup
Requests data
from server
Receives and stores data
into array
Awaits until array saves
200 data points and
starts graphing
Graphs and refreshes by
adding 5 newest data
points to and removing
oldest 5 data points from
the graph
HTML WebSocket
JavaScript
JQuery
Design Process

28. Last, but not least…
Importance of heart rate analysis