Hello, controlling a single LED at your command from the
computer was good but now the challenge is to control multiple LEDs from the
computer such that each LED is turned on and off at our wish.
Before this, you should read : Arduino Serial LED Control from Computer
We have to define a total of 12 variables, two
operations for each LED.
Mostly, alphabet/numeric keys from the computer keyboard are
used to give commands to the Arduino to control the output pins through the
serial communication.
Let’s get started with the Arduino multiple LEDs serial
communication project.
Things you will need:
1. Arduino Uno
2. Breadboard
3. Arduino Cable
4. LED 5V (red, yellow or green) *6
5. Jumper cables
6. Resistor – 220 ohm *6
Step 1: Making the Circuit
1. Fix the LEDs on the breadboard such that the two legs of the each LED do not short and the positive terminal (the longer leg) of each LED is not common with another LED.
2. Short or common the negative terminal (the shorter led) of
each LED and connect it to the Arduino Gnd.
3. Connect the pin 2 of the Arduino to the positive terminal of
the LED1 with jumper cable.
4. Connect the pin 3 of the Arduino to the positive terminal of
the LED2 with jumper cable.
5. Connect the pin 4 of the Arduino to the positive terminal of
the LED3 with jumper cable.
6. Connect the pin 5 of the Arduino to the positive terminal of
the LED4 with jumper cable.
7. Connect the pin 6 of the Arduino to the positive terminal of
the LED5 with jumper cable.
8. Connect the pin 7 of the Arduino to the positive terminal of
the LED6 with jumper cable.
Connect the 220 ohm resistor between each output pin and the
positive of the each LED so as to protect the LED from getting damaged.
Step 2: Uploading the Code
Enter the following code into the Arduino IDE or paste it. The
code would be called by the Arduino to check whether the value entered by us
matches. If it does, the corresponding operation would be performed.
In this
code, we use numeric commands in place of strings.
int incomingByte;
void setup(){
Serial.begin(9600);
pinMode(2,
OUTPUT);
pinMode(3,
OUTPUT);
pinMode(4,
OUTPUT);
pinMode(5,
OUTPUT);
pinMode(6,
OUTPUT);
pinMode(7,
OUTPUT);
}
void loop(){
if
(Serial.available() > 0) {
incomingByte = Serial.read();
if
(incomingByte == '1') {
digitalWrite(2, HIGH);
}
if
(incomingByte == '2') {
digitalWrite(2, LOW);
if
(Serial.available() > 0) {
incomingByte = Serial.read();
if
(incomingByte == '3') {
digitalWrite(3, HIGH);
}
}
if
(incomingByte == '4') {
digitalWrite(3, LOW);
incomingByte = Serial.read();
if
(incomingByte =='5'){
digitalWrite(4, HIGH);
}
}
if
(incomingByte == '6');
digitalWrite(4, LOW);
if
(Serial.available() > 0) {
incomingByte = Serial.read();
if
(incomingByte == '7') {
digitalWrite(5, HIGH);
}
}
if
(incomingByte =='8');
digitalWrite(5, LOW);
if
(Serial.available() > 0) {
incomingByte = Serial.read();
if
(incomingByte == '9') {
digitalWrite(6, HIGH);
}
}
if
(incomingByte =='10');
digitalWrite(6, LOW);
if
(Serial.available() > 0) {
incomingByte = Serial.read();
if
(incomingByte == '11') {
digitalWrite(7, HIGH);
}
}
if
(incomingByte =='12');
digitalWrite(7, LOW);
}
}
}
Now, connect the Arduino to the computer via the USB cable provided and choose the correct COM port. Click on the upload button from the toolbar. And, wait till the software says “Done Uploading”.
Step 3: LED Control from Computer
Now that the code is uploaded, open the serial monitor (Ctrl+Shift+M) from the
Arduino software, it may appear in a new window. The serial monitor would be
initially blank and has an input box on the top.
Enter “1”. The Led 1 should be turned on.
Whoa! Did you see that? The LED just turned on immediately
without delay.
Now, Enter “2”. The Led 1 should be turned off. Similarly, Enter “3”. The Led 2 should be turned on.
And so on...till the numbers hit 12.
All six LEDs may be turned on by hitting their respective
commands i.e 1,3,5,7,9,11 each at a time. So you get the idea that you may control the multiple output
pins from your computer and Arduino works as you wish.
Congratulations! You have just completed your Arduino Project
– simple, fun and easy.
Add or subtract the number of LEDs that may be maximum 14 (I/O
pins) by defining each pin as the output pin in the code. Example - pinMode(8, OUTPUT);
You may also read: Wireless Control of LED with Arduino andSmartphone
Stay Hungry! Stay Foolish!
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