Two ways/shematics ON/OFF Led Using Arduino

There are two ways to ON and OFF led using arduino:

1. Make schematic as follows:
   • Connect anode of led to pin 13 of arduino
   • Connect cathode of led to pin GND of arduino
   • Add resistor (example 150 Ω) series with led
   
   Then upload sketch as follows:
   
   int led = 13;
   
   void setup()
   {
     pinMode(led, OUTPUT);
   }
   
   void loop()
   {
     digitalWrite(led, HIGH); //led ON, change HIGH with LOW to led OFF
   }
   
   
2. Make schematic as follows:
   • Connect anode of led to pin 5V of arduino
   • Connect cathode of led to pin 13 of arduino
   • Add resistor (example 150 Ω) series with led
   
   Then upload sketch as follows:
   
   int led = 13;
   
   void setup()
   {
     pinMode(led, OUTPUT);
   }
   
   void loop()
   {
     digitalWrite(led, LOW); //led ON, change LOW with HIGH to led OFF
   }
   
   seem pin digital of arduino in condition LOW can be functioned as pin GND, really? not also know. ???(confuse...)

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