15. System Integration

Task of System Integration

• Design and document the system integration for your final project

This week of system integration I focused on integrating various subsystem into my project which is BMI Calculator; by unifying electronics, mechanics, and programming within a whole working device. The goal was to create a system that can precisely measure a person's weight and height, then compute their BMI and show it. Additionally; The divice send data to dashboard. These date will in turn be used to track the progress of people especially in school.

Subsystems

1. Load cell and its frame

Load cell is one of critical component which provides weight measurement. It is connected to an HX711 amplifier and an ESP32 microcontroller. The load cell was calibrated to ensure accurate weight measurements across a range of values.

The metal frame structure was thoroughly tested to ensure that load cell will be rigid. Metal plate holding it to the frame is 6mm thick. I previously used 3mm before but it was twisting and flexing considerably.

I then added extension to hold vertical beam.

This is supporting all other components including pcb and screen holder as well as that of ultrasonic sensor.

Cutting mechanical structure

All pieces were cut with cnc machine in 9mm MDF.

2. Ultrasonic Sensor

The ultrasonic sensor measures height of the person. It is positioned at the top of the device and communicates with the ESP32 via digital I/O. Its distance measurement is used to compute the person’s height. It is also enclosed in a 3D printed box for ease installation and disassembly.

3. Keypad

The keypad allows user input for setup, user identification, or starting the measurement. It connects to the ESP32 via a matrix interface, making it easy for the user to operate the device.

4. Screen

I used Nokia 5110 lcd screen to displays the results. After obtaining both weight and height, the ESP32 calculates the BMI and displays it clearly for the user.

Power button

I also included power button to power on and off the device.

System Architecture

The ESP32 serves as the central processor:

• Reads weight data from the load cell.
• Reads height data from the ultrasonic sensor.
• Processes the results using the BMI formula.
• Displays the calculated BMI

Data Flow Diagram:

        
          Load Cell --> HX711 --> ESP32 --> LCD
          Ultrasonic Sensor --> ESP32 --> LCD
          Keypad --> ESP32 --> LCD
        
      

Integration Process

Throughout this week:

• I verified individual component operation especially calibrating load cell which was the most challenging.
• I also created a pcb board for common wiring.
• I developed a combined program in Arduino IDE that deads weight and height, Processes user input from the keypad and then calculates and displays BMI of a user.
• After that, I tested with the machine in real-world by taking measurements.

Testing

This video show the machine in action taking measurements

Dashboard