(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/03.Analog/AnalogInOutSerial/AnalogInOutSerial.ino lang=arduino tabwidth=4:)

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/3.Analog/AnalogInOutSerial/AnalogInOutSerial.ino lang=arduino tabwidth=4:)

(:source http://github.com/arduino/Arduino/raw/new-extension/build/shared/examples/3.Analog/AnalogInOutSerial/AnalogInOutSerial.ino lang=arduino tabwidth=4:)

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Analog In, Out Serial

In order to scale this value, use a function called map()

(:source lang=arduino tabwidth=4:) outputValue = map(sensorValue, 0, 1023, 0, 255); (:sourceend:)

• map()
• analogRead()
• analogWrite()
• serial()

• AnalogReadSerial - read a potentiometer, print the state out to the serial monitor
• AnalogInput - use a potentiometer to control the blinking of an LED
• Fade - use an analog input to fade an LED
• Calibration - calibrating analog sensor readings

Next, in the main loop of the code, sensorValue is assigned to store the raw analog value coming in from the potentiometer. Because the Arduino has an analogRead resolution of 0-1023, and an analogWrite resolution of only 0-255, this raw data from the potentiometer needs to be scaled before using it to dim the LED.

In the program below, after declaring two pin assignments (analog 0 for your potentiometer and digital 9 for your LED) and two variables, sensorValue and outputValue, the only thing that you do will in the setup function is to begin serial communication.

outputValue is assigned to equal the scaled value from the potentiometer. map() accepts five arguments: The value to be mapped, the low range and high range of the raw data, and the low and high values for that data to be scaled too. In this case, the sensor data is mapped down from its original range of 0 to 1023 to 0 to 255.

The newly mapped sensor data is then output to the analogOutPin dimming or brightening the LED as the potentiometer is turned. Finally, both the raw and scaled sensor values are sent to the Arduino serial window in a steady stream of data.

This example shows how to read an analog input pin, map the result to a range from 0 to 255, and then use that result to set the pulsewidth modulation (PWM) of an output pin to dim or brighten an LED.

Code

In the program below, after declaring two pin assignments and two variables, sensorValue and outputValue, the only thing that you do will in the setup function is to begin serial communication.

Next, in the main loop of the code, sensorValue is assigned to store the raw analog value coming in from the potentiometer. Because the Arduino has an analogRead resolution of 0-1023, and an analogWrite resolution of only 0-255, this raw data needs to be scaled before using it to dim the LED.

In order to scale this value, a function called map() will be used. In the following line of code:

outputValue = map(sensorValue, 0, 1023, 0, 255);

outputValue is assigned to equal the scaled value from the potentiometer. map() accepts five arguments: The value to be mapped, the low range and high range of the raw data, and the low and high values for that data to be mapped too. In this case, the sensor data is scaled down from its original range of 0 to 1023 to 0 to 255.

Finally, the newly mapped sensor data is outputted to the analogOutPin dimming or brightening the LED as the potentiometer is turned. Both the raw and scaled sensor values are sent to the Arduino serial window in a steady stream of data.

Serial.println(sensorValue, DEC)

Now, when you open your Serial Monitor in the Arduino development environment (by clicking the button directly to the right of the "Upload" button in the header of the program), you should see a steady stream of numbers ranging from 0-1023, correlating to the position of the pot. As you turn your potentiometer, these numbers will respond almost instantly.

Connect one pin from your pot to 5V, the center pin to analog pin 0, and the remaining pin to ground. Next, connect a 220 ohm current limiting resistor to digital pin 9, with an LED in series. The long, positive leg (the anode) of the LED should be connected to the output from the resistor, with the shorter, negative leg (the cathode) connected to ground.

This example shows how to read an analog input pin, map the result to a range from 0 to 255, and then use that result to set the pulsewidth modulation (PWM) of an output pin, dimming and brightening an LED.

• Potentiometer
• LED
• 220 ohm resistor

analoginoutserial_sch.png

(:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/3.Analog/AnalogInOutSerial/AnalogInOutSerial.pde lang=arduino tabwidth=4:)

Examples > Analog

Example Name

Description

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Hardware Required

• Arduino Board

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Circuit

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image developed using Fritzing. For more circuit examples, see the Fritzing project page

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Schematic

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Describe what's going on here

(:div class=code :) (:source http://github.com/arduino/Arduino/raw/master/build/shared/examples/2.Analog/AnalogInOutSerial/AnalogInOutSerial.pde lang=arduino tabwidth=4:) (:divend:)

See Also:

• Reference page for this command?
• Other example in this category?