I cannot upload my program to an Arduino Nano due to a loop definition error code

Question

I was tasked with a college project which involved programming an Arduino board to flash two LEDs , which would display a number in binary code. I am about halfway through, but when I attempt to upload the program it keeps flashing the following error message. I have attached the code I have written so far and the error message below.

 void setup()
{
  // Set pin D2 as a digital output to control the LED
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
}

// The loop routine runs over and over until the power is switch off.
void loop()
{
  digitalWrite(2, HIGH); // Turn the LED on
  delay(1000);           // 1000 ms delay
  digitalWrite(2, LOW);  // Turn the LED off
  delay(1000);           // 1000 ms delay
 }
void loop()
{
  digitalWrite(3, LOW);
  delay(10000);
  digitalWrite(3, HIGH);
  delay(5000);
  digitalWrite(3, LOW);
  delay(2000);
digitalWrite(3, HIGH);
delay(1000);
digitalWrite(3, LOW);
delay(1000);
digitalWrite(3, HIGH);
delay(1000);
digitalWrite(3, LOW);
delay(8000);
digitalWrite(3, HIGH);
delay(8000);
digitalWrite(3, LOW);
delay(4000);
digitalWrite(3, HIGH);
delay(1000);
digitalWrite(3, LOW);
delay(5000);

Error:

C:\Users\matth\OneDrive\Documents\Arduino\flash\flash.ino: In function 'void loop()':
C:\Users\matth\OneDrive\Documents\Arduino\flash\flash.ino:21:6: error: redefinition of 'void loop()'
 void loop()
      ^~~~
C:\Users\matth\OneDrive\Documents\Arduino\flash\flash.ino:14:6: note: 'void loop()' previously defined here
 void loop()
      ^~~~

exit status 1

Compilation error: redefinition of 'void loop()

I tried removing the second void loop command, and also moving the digital input designation from between the two loops to above the first. However, I have no experience whatsoever with programming so I don't really know how to troubleshoot.

As the error message says, you simply cannot have two functions with the same name. You need to move both sets of code into a single void loop() { ... } structure - I can't tell you what form that would take, since I have no idea how your two current sets of code are supposed to interact. — jasonharper
– jasonharper, Commented Jan 26, 2024 at 21:42

lostbard · Accepted Answer · 2024-01-26 21:42:19Z

0

You have 2 loop functions - you can only have one. Remove one and it should compile and load fine.

Then it is just a matter of doing whatever you want it to do in the loop codewise.

Currently look like one loop is to turn on/off pin 2.
The other loop setting pin 3 high and low with various delays between the on/off
more information on how you are expecting the value to be flown on the pins would be needed.

answered Jan 26, 2024 at 21:42

lostbard

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1 Comment

mculleton04 Over a year ago

the idea is to have both LEDs flashing at the same time, as i will be using a camera based validator to verify that it displays the right number

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