pwmWrite()

Writes a PWM wave to a pin. You can use this to make an LED get brighter or dimmer, control a servomotor, etc. After a call to pwmWrite(), the pin will output a steady square wave with the given duty cycle. You can change the duty cycle later by calling pwmWrite() again with the same pin and a different duty.

On the Maple, the pins which support PWM are: 0, 1, 2, 3, 5, 6, 7, 8, 9, 11, 12, 14, 24, 27, and 28.

The Arduino function analogWrite() is an alias for pwmWrite(), but it is badly named, and its use is discouraged.

Library Documentation

void pwmWrite(uint8 pin, uint16 duty_cycle)

Set the PWM duty on the given pin.

User code is expected to determine and honor the maximum value (based on the configured period).

Example

Sets the output to the LED proportional to the value read from the potentiometer:

int analogPin = 3;    // potentiometer connected to analog pin 3

void setup() {
  pinMode(BOARD_LED_PIN, OUTPUT);   // sets the LED pin as output

  pinMode(analogPin, INPUT_ANALOG); // sets the potentiometer pin as
                                    // analog input
}

void loop() {
  int val = analogRead(analogPin);        // read the input pin

  pwmWrite(BOARD_LED_PIN, val * 16);  // analogRead values go from 0
                                      // to 4095, pwmWrite values
                                      // from 0 to 65535, so scale roughly
}

See Also

• Maple PWM tutorial