Arduino nano tachometer

Program Functionalities

This Arduino program is designed to interface with a two-channel incremental encoder and display the rotational speed of a roller on an LCD screen. The main functionalities of the program include:

Initialization of LCD and Encoder Pins

• The program initializes a 16x2 I2C LCD to display the calculated speed.
• It sets up two digital pins as inputs with internal pull-up resistors to read signals from the encoder.

Interrupt Handling for Encoder Pulses

• The program uses external interrupts on the encoder signal pins (CLK and DT) to accurately count pulses.
• Two interrupt service routines (ISRs) are defined: ai0() and ai1(). These routines increment the pulse counter based on the state of the encoder signals, ensuring the counter increases only in one direction to prevent negative values.

Real-Time Calculation of RPM and Speed

• The main loop of the program calculates the RPM (revolutions per minute) and the speed in meters per minute (m/min) every second.
• RPM is calculated using the formula:
  [ \text{RPM} = \frac{\text{counter} \times 60}{\text{pulses per revolution}} ]
• The speed in m/min is calculated using the formula:
  [ \text{Speed (m/min)} = \frac{\text{RPM} \times \pi \times \text{roller diameter}}{1000} ]
• After each calculation, the counter is reset for the next measurement period.

Displaying Speed on the LCD

• The calculated speed in m/min is displayed on the LCD screen.
• The LCD is updated every second with the new speed value, ensuring the display shows real-time data.