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Microcontroller-Based Heart-Rate Meter
Prof. K. Padmanabhan
introduction
Heart rate can be measured either by the ECG waveform or by the blood flow into the finger (pulse method). The pulse method is simple and convenient. When blood flows during the systolic stroke of the heart into the body parts, the finger gets its blood via the radial artery on the arm. The blood flow into the finger can be sensed photoelectrically. To count the heart beats, here we use a small light source on one side of the finger (thumb) and observe the change in light intensity on the other side. The blood flow causes variation in light intensity reaching the lightdependent resistor (LDR), which results in change in signal strength due to change in the resistance of the LDR.
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sir,
i have selected this topic as my project.i need some information of the components used in this project. the procedure to assemble them, its working and details.
i will be glad to seek your help.
thanks
ronald.
(ronald.dias35[at]gmail.com)
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for more on Microcontroller-Based Heart-Rate Meter, please download the attached file.
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Hello sir,
m interested in this project.
approximately how much funding will be required for this project?
thanking you in advance.
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full report Microcontroller-Based Heart-Rate Meter
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Hello sir, i m doing this project....but i m in the requirement of its HEX code....so will u be able to send it please....
thanking you in advance....
my email id is - teja.puranik[at]gmail.com
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CHAPTER 1
INTRODUCTION
1.1 OVERVIEW
Heart rate can be measured either by the ECG waveform the finger (pulse method). The blood flow into the finger (pulse method). The pulse method is simple and convenient. When blood flows during the systolic stroke of the heart into the body parts, the finger gets its blood via the radial artery on the arm. The blood flow into the finger can be sensed photo electrically.
To count the heart beats, here we use a small light source on one side of the finger (thumb) and observe the change in light intensity on the other side. The blood flow causes variation in light intensity reaching the light-dependent resistor (LDR), which results in change in signal strength due to change in the resistance of the LDR.
1.2 BENEFITS
Low Cost
Low power Consumption
Reliability
Easily accessible
User Friendly
Portability
1.3 SOFTWARE AND HARDWARE TOOLS
1.3.1 SOFTWARE
The Cross Assembler takes an assembly language source file created with a text editor and translates it into a machine language object file. This translation process is done in two passes over the source file. During the first pass, the Cross Assembler builds a symbol table from the symbols and labels used in the source file. It's during the second pass that the Cross Assembler actually translates the source file into the machine language object file. It is also during the second pass that the listing is generated. In this project we use ASM 51 cross assembler.
1.3.2 HARDWARE TOOLS
• AT89C2051 Microcontroller
• LM358 Operational amplifier
• ULN2003 current buffer
• Light dependent resistor
• Seven segment display
• Cathode ray oscilloscope
CHAPTER 2
Project description
2.1 CIRCUIT COMPONENTS
Semi conductors
Resistors
Capacitors
Miscellaneous
2.1.1 Semiconductors
• IC1 - LM358 operational amplifier
• IC2 - AT89C2051 microcontroller
• IC3 - ULN2003 current buffer
• T1-T3 - BC557 pnp transistor
• D1 - 1N4007 rectifier diode
• DIS1-DIS3 - LTS542 commonanode,7segmentdisplay
• LED1, LED2 - 5mm LED
2.1.2 Resistors (all ¼-watt, ±5% carbon)
• R1, R8 - 10-kilo-ohm
• R2 - 47-kilo-ohm
• R3 - 100-kilo-ohm
• R4, R5 - 1-kilo-ohm
• R6, R7 - 330-ohm
• R9-R11 - 1.2-kilo-ohm
• RNW1 - 10-kilo-ohm resistor network
2.1.3 Capacitors
• C1 - 470nF ceramic disk
• C2, C5, C8 - 0.1μF ceramic disk
• C3, C9 - 470μF, 16V electrolytic
• C4 - 10μF, 16V electrolytic
• C6, C7 - 22pF ceramic disk
2.2.4 Miscellaneous
• S1, S3 - On/Off switch
• S2 - Tactile switch
• XTAL - 11.0592MHz crystal
• BATT1, BATT2 - 6V battery
2.1 CIRCUIT DESCRIPTION AND OPERATION
The circuit of microcontroller based heart-rate meter setup shown in fig.2.1 uses a 6V electric bulb for light illumination of flesh on the thumb behind the nail and the LDR (Light Dependent Resistor) as detector of change in the light intensity due to the flow of blood. The photo-current is converted into voltage and amplified by operational amplifier IC LM358 (IC1). The detected signal is given to the non-inverting input (pin 3) and its output is fed to another non-inverting input (pin 5) for squaring and amplification. Output pin provides detected heartbeats to pin 12 of the AT89C2051 microcontroller. Preset VR1 is used for sensitivity and preset VR2 for trigger level settings.
Microcontroller IC AT89C2051 (IC2) is at the heart of the circuit. It is a20-pin, 8-bit microcontroller with 2 KB of Flash programmable and erasable read-only memory (PEROM), 128 bytes of RAM, 15 input/output (I/O) lines, two 16-bit timer/counters, a five-vector two-level interrupt architecture, a full duplex serial port, a precision analogue comparator, on-chip oscillator and clock circuitry. Port-1 pins P1.7 through P1.2, and port-3 pin P3.7 are connected to input pins 1 through 7 of IC ULN2003 (IC3), respectively. These pins are pulled-up with 10-kilo-ohm resistor network RNW1. They drive all the segments of the 7-segment display with the help of inverting buffer IC3
The displays are selected through port pins P3.0, P3.1 and P3.2 of the microcontroller (IC2). Port pins P3.0 down through P3.2 are connected to the base of transistors T3 through T1, respectively. Pin 6 of IC2 goes low to drive transistor T1 into saturation and provide supply to the common-anode pin (either pin 3 or pin 8) of DIS1.
Similarly, transistors T2 and T3 drive common-anode pin 3 or 8 of 7-segmentdisplays DIS2 and DIS3, respectively. Only three 7-segment displays are used. IC2 provides segment-data and display-enable signals simultaneously in time-division-multiplexed mode for displaying a particular number on the 7-segment display unit. Segment- data and display-enable pulses for the display are refreshed every 5ms. Thus the display appears to be continuous, even though it lights up one by one.
Switch S2 is used to manually reset the microcontroller, while the power on reset signal for the microcontroller is derived from the combination of capacitor C4 and resistor R8. An 11.0592MHz crystal is used to generate the basic clock frequency for the microcontroller. The circuit is powered by a 6V battery. Port pin P3.6 of the microcontroller is internally available for software checking. This pin is actually the output of the internal analogue comparator, which is available internally for comparing the two analogue levels at pins 12 and 13. As pins 12 and 13 of IC2 can work as an analogue comparator, these are used for sensing the rise and fall of the pulse waveform and there by evaluate the time between two peaks and hence the beat rate.
The output of the pulse pick-up preamplifier is fed to pin 12 of the microcontroller. Pin 13 of the microcontroller is connected to the preset for reference-level setting of the comparator. Thus voltages at pins 12 and 13 are always compared. The signal rise and the fall at pin 12 are sensed by the program.
The internal timer of the microcontroller is used to find the time taken for one wavelength. This time is converted into the heart beat rate in beats per minute by a pre-calculated look-up table. The program notes the time between the high-to low and low-to-high transitions of the wave.
This time in microseconds is converted in steps of 4 ms for comparison with the values already stored in the look-up table. This number is used to find (from the look-up table) the heart rate in beats per minute. The number so obtained is converted into a 3-digit number in binary-coded decimal (BCD) form. The same is output to the 7-segment LED displays in a multiplexed manner. The display shows the rate for a while and proceeds to another measurement. Thus beat rates obtained from time to time are visible on the display
CHAPTER 3
AT89C2051 MICROCONTROLLER
3.1 Description
The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer With 2 Kbytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51Ô instruction set and pin out. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.
The AT89C2051 provides the following standard features: 2 Kbytes of Flash,
128 bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, a precision analog comparator, on-chip oscillator and clock circuitry. In addition, the AT89C2051 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power Down Mode saves the RAM contents but freezes the oscillator disabling all other chip functions Until the next hardware reset.
3.2 FEATURES
1. Compatible with MCS-51Ô Products
2. Kbytes of Reprogrammable Flash Memory
3. Endurance: 1,000 Write/Erase Cycles 2.7 V to 6 V Operating Range
4. Fully Static Operation: 0 Hz to 24 MHz
5. Two-Level Program Memory Lock
6. 128 x 8-Bit Internal RAM
7. 15 Programmable I/O Lines
8. Two 16-Bit Timer/Counters
9. Six Interrupt Sources
10. Programmable Serial UART Channel
11. Direct LED Drive Outputs
12. On-Chip Analog Comparator
13. Low Power Idle and Power Down Modes
3.3 PIN CONFIGURATION
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28-11-2011, 08:50 PM
Thanks.
For Help Me.
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RE: Microcontroller-Based Heart-Rate Meter using pic
sir,
i have selected this topic as my project.i need some information of the components used in this project. the procedure to assemble them, its working and details.
i will be glad to seek your help.
thanks
deepu.d
(deepukgr[at]gmail.com)
