On most Arduino boards (those with the ATmega168 or ATmega328), this function works on pins 3, 5, 6, 9, 10, and 11. On the Arduino Mega, it works on pins 2 through 13. Older Arduino boards with an ATmega8 only support analogWrite() on pins 9, 10, and 11.

The Arduino Due supports analogWrite() on pins 2 through 13, plus pins DAC0 and DAC1. Unlike the PWM pins, DAC0 and DAC1 are Digital to Analog converters, and act as true analog outputs.

On most Arduino boards (those with the ATmega168 or ATmega328), this function works on pins 3, 5, 6, 9, 10, and 11. On the Arduino Mega, it works on pins 2 through 13. Older Arduino boards with an ATmega8 only support analogWrite() on pins 9, 10, and 11. The Arduino Due supports analogWrite() on pins 2 through 13, plus pins DAC0 and DAC1.

You do not need to call pinMode() to set the pin as an output before calling analogWrite().

On most Arduino boards (those with the ATmega168 or ATmega328), this function works on pins 3, 5, 6, 9, 10, and 11. On the Arduino Mega and Due, it works on pins 2 through 13. Older Arduino boards with an ATmega8 only support analogWrite() on pins 9, 10, and 11. You do not need to call pinMode() to set the pin as an output before calling analogWrite().

The analogWrite function has nothing to do with the analog pins or the analogRead function.

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• analogWriteResolution()

• AnalogWriteResolution()

The analogWrite function has nothing whatsoever to do with the analog pins or the analogRead function.

analogWrite has nothing whatsoever to do with the analog pins or analogRead().

On most Arduino boards (those with the ATmega168 or ATmega328), this function works on pins 3, 5, 6, 9, 10, and 11. On the Arduino Mega, it works on pins 2 through 13. Older Arduino boards with an ATmega8 only support analogWrite() on pins 9, 10, and 11. You do not need to call pinMode() to set the pin as an output before calling analogWrite().

The PWM outputs generated on pins 5 and 6 will have higher-than-expected duty cycles. This is because of interactions with the millis() and delay() functions, which share the same internal timer used to generate those PWM outputs. This will be noticed mostly on low duty-cycle settings (e.g 0 - 10) and may result in a value of 0 not fully turning off the output on pins 5 and 6.

analogWrite has nothing whatsoever to do with the analog pins or analogRead.

analogWrite has nothing to do with the analog pins or analogRead.

The PWM outputs generated on pins 5 and 6 will have higher-than-expected duty cycles. This is because of interactions with the millis() and delay() functions, which share the same internal timer used to generate those PWM outputs. This will be noticed mostly on low duty-cycle settings (e.g 0 - 10) and may result in analogWrite(x, 0) not fully turning off the output on pins 5 & 6, as one would expect.

The PWM outputs generated on pins 5 and 6 will have higher-than-expected duty cycles. This is because of interactions with the millis() and delay() functions, which share the same internal timer used to generate those PWM outputs. This will be noticed mostly on low duty cycle settings (e.g 0 - 10) and may result in analogWrite(x, 0) not fully turning off the output on pins 5 & 6, as one would expect.

• Adjusting Arduino PWM Frequencies

• Adjusting Arduino PWM Frequencies?

• Tutorial: PWM

• Tutorial: Explanation of PWM

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite(), the pin will generate a steady square wave of the specified duty cycle until the next call to analogWrite() (or a call to digitalRead() or digitalWrite() on the same pin). The frequency of the PWM signal is approximately 490 Hz.

• analogRead()

analogWrite()

Syntax

analogWrite(pin, value)

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite, the pin will generate a steady square wave of the specified duty cycle until the next call to analogWrite (or a call to digitalRead or digitalWrite on the same pin). The frequency of the PWM signal is approximately 490 Hz.

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite, the pin will generate a steady square wave of the specified duty cycle until the next call to analogWrite (or a call to digitalRead or digitalWrite on the same pin). The frequency of the PWM signal is approximately 490 Hz.

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite, the pin will generate a steady wave until the next call to analogWrite (or a call to digitalRead or digitalWrite on the same pin). The frequency of the PWM signal is approximately 490 Hz.

On newer Arduino boards (including the Mini and BT) with the ATmega168 chip, this function works on pins 3, 5, 6, 9, 10, and 11. Older USB and serial Arduino boards with an ATmega8 only support analogWrite() on pins 9, 10, and 11.

value: the duty cycle: between 0 (always off) and 255 (always on).

The PWM outputs generated on pins 5 and 6 will have higher-than-expected duty cycles. This is because of interactions with the millis() and delay() functions, which share the same internal timer used to generate those PWM outputs.

The PWM outputs generated on pins 5 and 6 will have higher-than-expected duty cycles. This is because the internal timer used to generate the PWM signals on pins 5 and 6 is also used for the millis() and delay() functions.

• Explanation of PWM

Notes and Known Issues

The millis() and delay() functions apparently interfere with the PWM signal on pins 5 and 6 causing them to report a higher-than-expected average voltage.

You do not need to call pinMode() to set the pin as an output before calling analogWrite().

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

int ledPin = 9; // LED connected to digital pin 9

int val = 0; // variable to store the read value

Writes an analog value (PWM wave) to a pin. On newer Arduino boards (including the Mini and BT) with the ATmega168 chip, this function works on pins 3, 5, 6, 9, 10, and 11. Older USB and serial Arduino boards with an ATmega8 only support analogWrite() on pins 9, 10, and 11.

The frequency of the PWM signal is approximately 490 Hz.

Writes an analog value (PWM wave) to a pin. On normal Arduino boards (e.g. Arduino NG), this works on pins 9, 10, or 11. On the Arduino Mini, this also works on pins 3, 5, and 6.

Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite, the pin will generate a steady wave until the next call to analogWrite (or a call to digitalRead or digitalWrite on the same pin).

Writes an analog value (PWM wave) to pins 9, 10, or 11. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite, the pin will generate a steady wave until the next call to analogWrite (or a call to digitalRead or digitalWrite on the same pin).

value: the duty cycle: between 0 and 255. A value of 0 generates a constant 0 volts output at the specified pin; a value of 255 generates a constant 5 volts output at the specified pin. For values in between 0 and 255, the pin rapidly alternates between 0 and 5 volts - the higher the value, the more often the pin is high (5 volts). For example, a value of 64 will be 0 volts three-quarters of the time, and 5 volts one quarter of the time; a value of 128 will be at 0 half the time and 255 half the time; and a value of 192 will be 0 volts one quarter of the time and 5 volts three-quarters of the time.

Pins taking analogWrite (9-11), unlike standard digital ones (1-8, 12, 13), do not need to be declared as INPUT nor OUTPUT

analogWrite only works on pins 9, 10, and 11; on all other pins it will write a digital value of 0 or 5 volts.

Writes an analog value (PWM wave) to pin 9 or 10. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite, the pin will generate a steady wave until the next call to analogWrite (or a call to digitalRead or digitalWrite on the same pin).

value: the duty cycle: between 0 and 255. 0 corresponds to constant low output (no voltage); 255 is a constantly on output (5 volts). For values in-between, the pin rapidly alternates between 0 and 5 volts - the higher the value, the more often the pin is high (5 volts).

analogWrite only works on pins 9 and 10; on all other pins it will write a digital value of 0 or 5 volts.

The frequency of the PWM signal is approximately 30769 Hz

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. analogWrite only works on pins 9 and 10; on all other pins it will write a digital value of 0 or 5 volts.

Returns

Reference Home

analogWrite(pin, value)

Description

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. analogWrite only works on pins 9 and 10; on all other pins it will write a digital value of 0 or 5 volts.

Parameters

pin: the pin to write to.

value: the value between 0 and 255. 0 corresponds to constant low output (no voltage); 255 is a constantly on output (5 volts). For values in-between, the pin rapidly alternates between 0 and 5 volts - the higher the value, the more often the pin is high (5 volts).

This function returns

nothing

analogWrite

What it does

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds.

What parameters does it take

The pin to write to. analogWrite only works on pins 9 and 10; on all other pins it will write a digital value of 0 or 5 volts.

The value between 0 and 255. 0 corresponds to constant low output (no voltage); 255 is a constantly on output (5 volts). For values in-between, the pin rapidly alternates between 0 and 5 volts - the higher the value, the more often the pin is high (5 volts).

Note

Analog pins unlike digital ones, do not need to be declared as INPUT nor OUTPUT

Example

 
int ledPin = 9;   // LED connected to digital pin 9
int analogPin = 3;   // potentiometer connected to analog pin 3
int val = 0;   // variable to store the read value

void setup()
{
  pinMode(ledPin, OUTPUT);   // sets the pin as output
}

void loop()
{
  val = analogRead(analogPin);   // read the input pin
  analogWrite(ledPin, val / 4);  // analogRead values go from 0 to 1023, analogWrite values from 0 to 255
}

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

See also

• pinMode
• digitalWrite
• analogRead