analogWrite - Power Control
Background
analogWrite() uses PWM or Pulse Width Modulation to control how much power is being delivered via a digital pin. PWM is a technique for getting pseudo-analog results with digital means. It does not write a true analog value. Digital control is used to create a square wave (signal switched between on & off). The average power is increased or decreased by pulsing the voltage at a very fast rate and controlling the "on" time. Used to control intensity like the speed of motors or brightness of LEDs.
Hardware Description
- Only specific pins on the Arduino can do PWM. These pins are typically labeled with a tilde ~.
- On the Arduino Uno, the pins are 3, 5, 6, 9, 10, 11.
- The frequency is 490 Hz (pins 5 and 6: 980 Hz).
Software Description
analogWrite(pin, value)- sends a PWM wave only works on pins with tilde ~ (pins 3, 5, 6, 9, 10, 11)pin: the Arduino pin to write to.value: the duty cycle: between 0 (always off) and 255 (always on).
Project Ideas
- Use it to control the brightness of an LED.
- Use it to color mix an RGB LED.
- Use it to control the speed of a motor.