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Pulse Width Modulation (PWM) is a technique used to control the amount of power delivered to electronic devices. It is commonly used in Arduino projects to manage motor speeds, LED brightness, and other applications requiring variable power levels. Understanding how to calculate the duty cycle and apply it effectively is essential for precise control.
What is Duty Cycle?
The duty cycle represents the percentage of time a signal is in the “high” state within one cycle. It determines the average power delivered to a device. A duty cycle of 100% means the signal is always on, while 0% means it is always off.
Calculating Duty Cycle
The duty cycle is calculated using the formula:
Duty Cycle (%) = (On Time / Total Period) × 100
For example, if the PWM period is 20 milliseconds and the signal is high for 5 milliseconds, the duty cycle is:
(5 ms / 20 ms) × 100 = 25%
Applying Duty Cycle in Arduino
In Arduino, the analogWrite() function is used to generate PWM signals. It accepts a value between 0 and 255, corresponding to a duty cycle from 0% to 100%.
The formula to convert a percentage duty cycle to the Arduino value is:
Value = (Duty Cycle % / 100) × 255
For a 50% duty cycle, the Arduino value would be:
(50 / 100) × 255 ≈ 127
Summary
Understanding how to calculate and apply duty cycle allows for precise control of electronic components in Arduino projects. By adjusting the PWM signal, users can effectively manage power delivery to various devices.