Analog In, Out Serial

This example shows you how to read an analog input pin, map the result to a range from 0 to 255, use that result to set the pulse width modulation (PWM) of an output pin to dim or brighten an LED and print the values on the serial monitor of the Arduino Software (IDE).

Step 1: What You Need?

1 x Arduino Board (Arduino UNO used in this tutorial)
1 x Potentiometer (10k)
1 x LED (Red)
1 x 220 Ohm Resistor 

Female-to-Male Jumper Wires 

Optional 
Male-to-Male Jumper Wires 
1 x Mini Breadboard

Don't have components? Don't worry. Just click the component's name. 

Step 2: Build Your Circuit.

Connect one pin from your potentiometer 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.

Step 3: Upload The Code.

1. Select the Arduino board type: Select Tools >> Board >> Select your correct Arduino board used.

2. Find the port number by accessing device manager on Windows. See the section Port (COM&LPT) and look for an open port named "Arduino Uno (COMxx)". If you are using a different board, you will find a name accordingly. What matters is the xx in COMxx part. In my case, it's COM3. So my port number is 3.

Select the right port: Tools >> Port >> Select the port number.

3. You can find this code in the example of Arduino IDE.
Select File >> Examples >> 03.Analog >> AnalogInOutSerial

Click press the "upload" button (see the button with right arrow mark).

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

Next, in the main loop, sensorValue is assigned to store the raw analog value read from the potentiometer. Arduino has ananalogRead range from 0 to 1023, and an analogWrite range only from 0 to 255, therefore the data from the potentiometer needs to be converted to fit into the smaller range before using it to dim the LED.

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

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 values of the input data, and the low and high values for that data to be remapped to. 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 Software (IDE) serial monitor window, in a steady stream of data.

Download: 

Arduino software

Sources:https://www.arduino.cc/en/Tutorial/AnalogInOutSerial

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Author & Editor

My Robot Education Sdn. Bhd. (Robotedu.my) was founded in 2015 as the first robotics education centre in Malaysia to provide Arduino-based robotics courses for youths. Our vision is to be able to provide robotics education to every youth in Malaysia.