This document summarizes a project report on developing a real-time pulse detector. It introduces the components of the heart and how blood flows through it. The project uses a fingertip sensor with an infrared LED and photodiode to detect changes in blood volume and flow. An ATmega32 microcontroller processes the sensor signals and displays the measured heart rate on a 16x2 LCD display. The circuit diagram and code implementation are described. Test results on 10 subjects show an average error rate of 1.414% between the device's measured heart rate and a measurement using an oscilloscope. The conclusion discusses how the infrared sensor provides a more stable output signal than pressure sensors and how the device can help monitor heart rate during exercise or

1. A Minor Project Report On
“REAL TIME PULSE DETECTOR”
by: SHATRUGHAN PATEL
DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING
BRANCH: ELECTRONICS & COMMUNICATIONS

2. INTRODUCATION
• The heart is the organ that responsible for pumping blood throughout
the body. It is located in the middle of the thorax, slightly offset to the
left and surrounded by the lungs basically; the human heart is
composed of four chambers which are two atriums and two
ventricles. The right atrium receives blood returning to the heart from
the whole body. That blood passes through the right ventricle and is
pumped to the lungs where it is oxygenated and goes back to the
heart through the left atrium, and then the blood passes through the
left ventricle and is pumped again to be distributed to the entire body
through the arteries

3. MATERIAL AND TOOLS
• The fingertip sensor - The heart rate monitor builds to test the value of users’ heart rate
currently. The circuit will base on the non-invasive PPG sensor which detects the variation of the
blood flow in finger when the mechanical contraction of heart. The sensor contains an infrared
LED as an IR transmitter and photodiode as an IR receiver.
• ATMEGA32 Microcontroller - The high-performance, low-power Atmel 8-bit AVR RISC-based
microcontroller combines 16KB of programmable flash memory, 2KB SRAM, 1KB EEPROM, an
8channel 10-bit A/D converter, 2 capture/compare/PWM functions, 3 timers, a synchronous serial
port that can be configured as either 3-wire SPI or 2-wire I2C bus, a USART, and a Parallel Slave
Port. The device supports throughput of 16 MIPS at 16 MHz and operates between 4.5-5.5 volts

4. ATMEGA32 Microcontroller PIN DIAGRAM -

5. Fingertip sensor - Use of light to measure heart rate is a field of study where abundant research has been
done in the past few decades. Fingertip sensor relies on measurement of a physiological signal called
Photoplethysmogrpahy (PPG) [14.], which is an optical measurement of the change in blood volume in
the arteries. Fingertip sensor acquires PPG signals by irradiating wavelength of light through the tissue,
and compares the light absorption characteristics of blood under these wavelengths
High level design -
By high level design we mean to see the project from an
overall view point, then to get down and consider the
project as a system of main parts.
Fingertip sensor is used in the device as transducer converts
the physical PPG signal to into an electrical signal. This
electrical signal is applied to the microcontroller which is
the main brain of the heart rate monitor. The
microcontroller, according to the

6. CIRCUIT
DIAGRAM

7. • This project used LM358 two-class amplifier to adjust the voltage value to 5V for being received by ATMEGA32.
Because the signal acquisition is extremely weak and vulnerable to interference by the external circuit, high-pass
filter and low-pass filter are used for normal heart beat signals.
• The amplifier (see figure 4.9) uses an LM358 dual op amp to provide two identical broadly-tuned low pass stages
with the gain of each filter stage is set to 101 and a cut-off frequency of about 2.34 Hz. So the maximum HR that
could be read is approximately equal 150. The equations for calculating gain and cut-off frequency of the active
low pass filter are expressed as

8. LCD
• In this project, a 16×2 LCD display will be used for displaying the value of heart rate.
There are 16 pins in whole in LCD. The pin diagram of LCD is shown as below. From the
datasheet, it is known that pin 1 & pin 2 and pin 15 & pin 16 both functions as power
supply ports. However, just pin 1 & pin 2 needed, and the lightness of LCD should be
controlled by a 10kΩ variable resistor.

9. RESULT
gender Age HR on display HR on oscilloscope Error rate (%)
Male 22 97 96 1.03
Male 22 83 81 2.41
Male 20 78 78 0
Male 22 90 87 3.33
Male 20 80 79 1.25
Female 22 77 77 0
Female 22 104 103 0.96
Female 19 75 75 0
Female 20 69 71 2.81
The accuracy of the device depends on the testing performed is about
1.414. In general, the HR of females is higher than males. But this is not
true where difference in weight, daily life (i.e. kind of work, health,
inheritance of heart disease, doing exercises… etc).

10. CONCLUSION
Infrared sensor instead of pressure sensor was used in Heart Rate
Monitor, it has higher sensitivity, and the output signal is more stability.
The infrared sensor depends on the fact that the speed of blood is
proportional to heart rate. That is to say, when people are in high active,
the heart rate will change. As the same theory as previous research, heart
rate changes when people are excited. The HR value displayed on LCD
shows the information that when people took exercise, the heart rate will
increase; sometimes it is out of healthy range. When people take a break,
the normal heart rate will recover.
In totally, heart rate is physiological indicators to show what is going on in body.
People need to care about their healthy condition with the help of Heart Rate Monitor.

11. References
[1] Sokwoo Rhee “DESIGN AND ANALYSIS ARTIFACTRESISTIVEFINGER
PHOTOPLETHYSMOGRAPHIC SENSORS FOR VITAL SIGN MONITORING”
Massachusetts,U.S, 2001, chapter1,P9.
[2] World health organization, Mortality country fact sheet 2006, Sudan. .
WEB URL-
[3] Wikipedia – http://en.wikipedia.org/wiki/Main_Page.

12. THE END
THANK YOU