The project involves the design and implementation of a system that measures the rotational speed (RPM) of a spinner using a hall magnetic sensor. The measured RPM is then displayed in real-time on an LCD screen, providing an intuitive interface for monitoring rotational speed.

Hall Magnetic Sensor: Detects the presence of a magnetic field, generating pulses with each rotation.

Microcontroller: Processes signals from the Hall sensor and calculates the RPM.

LCD Display: Shows the calculated RPM in a readable format.

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🛠️ เจาะลึกเบื้องหลังการทำงาน (Deep Dive / Technical Analysis)

Whether you are matching spindle speeds on a CNC machine or testing an RC motor, you need an exact RPM readout. The RPM Tracker utilizes light reflection and high-speed hardware interrupts to build a digital tachometer.

Optical Interrupt Mathematics

1. The Setup: You place a tiny strip of highly reflective silver tape onto the black spinning shaft of your motor.
2. The Sensor: You point a TCRT5000 IR Reflective Sensor at the shaft. Every time the silver tape spins past the laser, the sensor pin flashes HIGH for a microsecond.
3. The Hardware Interrupt: To ensure the Arduino doesn't "miss" the flash, you attach the pin to attachInterrupt(0, countPulse, RISING);. The Arduino increments a hits variable every single time it sees a flash.
4. The Calculation: Every 1,000 milliseconds (using millis()), the code stops counting.
   • RPM = (hits / holes_in_disc) * 60;
   • It prints 3400 RPM to an LCD, resets the hits variable to 0, and starts counting again!

Hall Effect Alternative

If the environment is covered in dirt or oil (like a real car engine), optical IR sensors will get blocked. You swap the sensor for a Magnetic Hall Effect Sensor and glue a tiny neodymium magnet to the spinning shaft. The code remains exactly the same!

Required Parts

• Arduino Uno/Nano: The calculator.
• TCRT5000 IR Obstacle Sensor OR Hall Effect Sensor.
• 16x2 Text LCD Screen.
• A 12V PC Fan or DC motor to test it on!