E&TC / ECE · Embedded and digital electronics · Final year project
Automatic BMI Calculator Using Load Cell & Height Sensing
A machine that measures BMI without any input. A load cell measures weight and an ultrasonic sensor overhead measures height, and a microcontroller calculates BMI and shows the body type on a display.
What is the Automatic BMI Calculator Using Load Cell & Height Sensing project?
A machine that measures BMI without any input. A load cell measures weight and an ultrasonic sensor overhead measures height, and a microcontroller calculates BMI and shows the body type on a display.
Key facts
- Branch
- Electronics & Telecommunication (E&TC / ECE); also suits Electrical
- Type
- Final year project · Intermediate
- Suitable for
- Diploma capstone and B.E / B.Tech final year
- Build time
- 4 to 6 weeks
- Estimated component cost
- ₹2,600 – ₹3,800
- Guidance from
- ₹9,999 (Hardware / IoT Final Year)
How the Automatic BMI Calculator Using Load Cell & Height Sensing works
- 12 V power adapter / step-down transformer supplies the circuit; a regulator gives the controller and sensors a steady 5 V.
- The Load cell with HX711 amplifier measures weight.
- The Ultrasonic sensor measures distance to an obstacle or a liquid surface using sound echoes.
- The Push buttons and switches provide manual inputs and the power switch.
- The 8051 microcontroller with board runs the embedded C program that scans inputs and controls the outputs through its four I/O ports.
- The 433 MHz RF transmitter-receiver pair sends the remote's button press wirelessly to the receiver circuit.
- The 16×2 LCD with I2C adapter shows readings, status and messages to the user.
- The LEDs indicate status.
Block diagram
Inputs
Load cell with HX711 amplifierUltrasonic sensorPush buttons and switchesController
8051 microcontroller with boardCommunication
433 MHz RF transmitter-receiver pairOutputs
16×2 LCD with I2C adapterLEDsComponents list and cost
Typical prices from Indian online stores and electronics markets (Lamington Road, Budhwar Peth, SP Road). Buy from one store where you can to save on shipping.
| Component | Qty | What it does | Approx. cost |
|---|---|---|---|
| 8051 (AT89S52) microcontroller with board | 1 | Runs the embedded C program that scans inputs and controls the outputs through its four I/O ports. | ₹300 |
| Load cell with HX711 amplifier | 1 | Measures weight. | ₹350 |
| Ultrasonic sensor (HC-SR04) | 1 | Measures distance to an obstacle or a liquid surface using sound echoes. | ₹90 |
| Push buttons and switches | 1 | Provide manual inputs and the power switch. | ₹40 |
| 433 MHz RF transmitter-receiver pair | 1 | Sends the remote's button press wirelessly to the receiver circuit. | ₹150 |
| 16×2 LCD with I2C adapter | 1 | Shows readings, status and messages to the user. | ₹220 |
| LEDs (assorted) | 1 | Indicate status. | ₹20 |
| 12 V power adapter / step-down transformer | 1 | Supplies stable low-voltage power from the mains. | ₹250 |
| Passive components, PCB and wiring kit | 1 | Crystal oscillator, resistors (assorted), capacitors (assorted), transistors / MOSFETs, cables, connectors and jumper wires, diodes and PCB / breadboard. | ₹385 |
| Wiring, PCB, soldering and enclosure | 1 | Project overhead | ₹450 |
| Demo model base / mounting board | 1 | Project overhead | ₹500 |
| Testing spares and replacements | 1 | Project overhead | ₹300 |
| Estimated total | Varies with brand, quality and city | ₹2,600 – ₹3,800 |
Prices are estimates for budgeting. We confirm the bill of materials when your design is frozen, and components are charged at actual cost with bills.
How much does this project cost?
| Option | What you get | Cost |
|---|---|---|
| Components only | You buy the parts and build it yourself | ₹2,600 – ₹3,800 |
| Hardware / IoT Final Year | Working model or guided build, Circuit diagram and bill of materials, Firmware / code with explanation | from ₹9,999 + components |
| Capstone Project (CPE) | Working project or model, Black book in MSBTE format, Step-by-step explanation | ₹9,999 + components |
| Diploma ITR | 100% working source code, Project report PDF, PPT | ₹1,999 + components |
No GST and no hidden charges. Use the cost calculator for a quote with your deadline and add-ons, or see all plans.
Download the project brief (PDF)
Summary, working, components and cost and viva questions on one branded PDF to show your guide or team. To get it developed, contact us on WhatsApp.
What you submit with this project
- Working model with circuit diagram and program code
- Project report or black book in your university's chapter order (block diagram, circuit, calculations, results)
- Presentation for the review and final viva
- Synopsis for topic approval, if your college asks for one
E&TC / ECE viva questions on this project
What is the aim of the Automatic BMI Calculator Using Load Cell & Height Sensing project?
A machine that measures BMI without any input. A load cell measures weight and an ultrasonic sensor overhead measures height, and a microcontroller calculates BMI and shows the body type on a display.
Explain the working of your project in short.
12 V power adapter / step-down transformer supplies the circuit; a regulator gives the controller and sensors a steady 5 V. The Load cell with HX711 amplifier measures weight. The Ultrasonic sensor measures distance to an obstacle or a liquid surface using sound echoes. The Push buttons and switches provide manual inputs and the power switch.
What is the architecture of the 8051 microcontroller?
The 8051 is an 8-bit Harvard-architecture microcontroller with 4 KB ROM (8 KB in AT89S52), 128 bytes RAM, four 8-bit I/O ports, two 16-bit timers, a UART and five interrupt sources.
How does a load cell measure weight?
Strain gauges bonded to the metal beam change resistance as it bends. They form a Wheatstone bridge whose tiny output is amplified and digitised by the 24-bit HX711.
How does the ultrasonic sensor measure distance?
It sends a 40 kHz pulse and measures the time until the echo returns. Distance = (time × speed of sound 343 m/s) ÷ 2. The HC-SR04 works from 2 cm to about 4 m.
Why is a pull-up resistor needed with a push button?
Without it the input pin floats and reads random values. The pull-up keeps it HIGH until the button connects it to ground.
Why are encoder and decoder ICs used with the RF module?
The HT12E encoder converts parallel button inputs into a serial code with an address, and the HT12D decoder on the receiver checks the address and restores the outputs. This prevents interference from other remotes.
Explain the block diagram of your project.
The input section senses the real-world quantity, the 8051 microcontroller with board processes it according to the program, and the output section acts locally and sends the data or alert wirelessly. The power supply section feeds every block.
Which communication protocols are used between the modules?
I2C for the display, RTC or motion sensor (only SDA and SCL lines). Each protocol was chosen because the module supports it and it uses the fewest pins.
What is the operating voltage of the circuit?
The controller and most sensors work at 5 V (ESP boards and some modules at 3.3 V). A 12 V adapter powers the board, and a regulator steps it down. Motors and relays get their own supply line so they do not reset the controller.
How did you calculate the power rating of your system?
Using P = V × I for each load, adding a margin of 20 to 25%.
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