the circuit of microcontroller-based heart-rate meter. The setup uses a 6V electric bulb for light illumination of flesh on the thumb behindthe nail and the LDR 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 7 provides detected heartbeats to pin 12 of the 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 a 20-pin, 8-bit microcontroller with 2 Kb of Flash programmable and erasable read-only memory (EPROM), 128 bytes of RAM, 15 input/output (I/O) lines,two 16-bit timer/counters, a five-vector two-level interrupt architecture, a fullduplex 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 ofinverting buffer IC3.
• The main application of this equipment is to calculate the heart rate of a human body just by a finger tip .the heart rate is measured to monitor the blood circulation of the human body through heart.
• The rate when the pulse returns to normal is an indication of the fitness of the person.
• Lower than normal heart rates are usually an indication of a condition known as bradycardia
• while higher than normal heart rates are known as tachycardia.
The project ËœHeart Beat Monitorâ„¢ is a very useful project especially for medical field. This can be used to monitor the heart beat in digital display format. In this project two electrodes were used to sense the blood pumping done by heart which is proportional to heartbeats. The sensing electrodes sense the blood pumping cycles and send the signal to current amplifier. The amplified signals are processed to extract the number of cycles of blood through our body. The average value of sensed cycles of blood pumps are displayed per minute interval. Microcontroller AT89S51 is used to process and displayed on 16x2 LCD display
sbit lcd_d7 = P2^3;//LCD...