user1296: How to make an input from computer using processing (like a password form) and trigger pin in arduino?
If you let some link to read more that would be very helpful.

user679: On the processing side you need to communicate with the arduino using the Serial class. To set up use something like the following. It is a bit of guess work 
to find which of the serial ports to use
Serial myPort;  
void setup() {
  // List all the available serial ports:
  println(Serial.list());

  // Open the port you are using at the rate you want:
  myPort = new Serial(this, Serial.list()[6], 9600);
  myPort.buffer(2); // sets the size of the buffer, I send two bytes at a time
}

You can read a write using the Serial.read() and Serial.write() see https://processing.org/reference/libraries/serial/index.html for the processing serial references.

1296: <p>How to make an input from computer using processing (like a password form) and trigger pin in arduino?
If you let some link to read more that would be very helpful.</p>
 679: <p>On the processing side you need to communicate with the arduino using the Serial class. To set up use something like the following. It is a bit of guess work 
to find which of the serial ports to use</p>

<pre><code>Serial myPort;  
void setup() {
  // List all the available serial ports:
  println(Serial.list());

  // Open the port you are using at the rate you want:
  myPort = new Serial(this, Serial.list()[6], 9600);
  myPort.buffer(2); // sets the size of the buffer, I send two bytes at a time
}
</code></pre>

<p>You can read a write using the <code>Serial.read()</code> and <code>Serial.write()</code> see <a href="https://processing.org/reference/libraries/serial/index.html" rel="nofollow">https://processing.org/reference/libraries/serial/index.html</a> for the processing serial references.</p>
