Interfacing an LED to a microcontroller

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First identify which is the anode and cathode,the shorter leg is the cathode(negative) and longer leg is anode(positive).

Now we will see how to interface  a LED to a microcontroller. We can do this in two ways.

Method 1: Connect the anode to a microcontroller GPIO pin and cathode to ground with a resistor connected between anode and the microcontroller pin , to reduce current flowing into the led . The value of the resistor depends on the amount of the current that can be supported by the LED.In order to ON the LED we have to send a Logical High from the microcontroller pin.

Method 2:  Connect the cathode to the microcontroller GPIO pin and anode to the 5V with a resistor i between. Now we have to send a logical LOW from the microcontroller pin for making the LED glow


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