Tachometer with LED display using Arduino

This digital tachometer system calculates and displays the rotational speed of an object in revolutions per minute (RPM) using an Arduino Uno as the central processing unit. The primary sensing mechanism relies on an infrared (IR) sensor module, which emits an infrared beam and detects its reflection. As a small rod attached to the rotating object spins past the sensor, it periodically interrupts or reflects the IR beam, generating a pulsed electrical signal corresponding to each complete rotation. The Arduino Uno reads these incoming digital pulses via its general-purpose input/output pins, utilizing a software routine to count the transitions over a fixed time interval or measure the time elapsed between consecutive pulses. Once the rotational frequency is computed into standard RPM units, the Arduino transmits this numerical data to a TM1637-based 4-digit LED segment display. The TM1637 driver handles the multiplexing and segment illumination required to render the digits clearly on the screen. Power and signal routing between the Arduino Uno, IR sensor, and display module are established using jumper wires, creating a self-contained embedded instrumentation tool suitable for real-time speed monitoring.