How to count positive electrical pulses? I have a device that has one blinking LED.
I want to count the number of blinks. I planned to do it using Arduino. I will connect two terminals of LED input to Arduino digital input pins, and I will count the number of positive voltage pulses
I just want to know if it is possible? and if yes then can you please hint the code for the same?
You should not count the number of pulses, but the number of transition from 0 to VCC volts or VCC to 0 volts (called rising resp. falling edge).

If you don't want to solder, you can also use a light dependent resistor (LDR) very close by the LED to measure the difference in brightness. See also chrisl's remark below.

The counting you can do manually (in a loop, check as often as possible or needed), or by setting up a timer to check for either rising or falling edges.

I will give the pseudo code so you can figure out the actual code:

bool _ldrPin;
unsigned long int _counter;


setup()
{
   // Set Serial
   Serial.begin(9600);

   // Set LDR
   setAnalogPin(X, INPUT);
   _ldrPin = readAnalog(X);
}

loop()
{
    if (!_ldrPin &amp;&amp; readAnalog(X) == HIGH)
    {
        // Rising edge, increase counter
        _counter++;
        Serial.Write(_counter);
        _ldrPin = true;
    }
    else if (ldrPin &amp;&amp; readAnalog(X) == LOW)
    {
       // Falling edge, reset status
        _ldrPin = false;
    }
}