How much Voltage will be present at the GPIO pin for a Microcontroller which has a Vcc(Input Supply voltage) of 3.3V ?
Suppose I need to connect an LED at this GPIO what are the factors or calculations that I have to consider ?

And, How much voltage should I apply to an LED to turn it on? What should be its supply voltage?

 

You don't mention which microcontroller you are using. Generally such information about voltage is in the electrical specifications section of the datasheet. If you are talking PIC's, here are data for the 12F509, which has a GPIO port:


Remember that the maximum allowed current from a pin is 25 mA (also in the electrical specifications)

John

 

How much Voltage will be present at the GPIO pin for a Microcontroller which has a Vcc(Input Supply voltage) of 3.3V ?
Suppose I need to connect an LED at this GPIO what are the factors or calculations that I have to consider ?

And, How much voltage should I apply to an LED to turn it on? What should be its supply voltage?

Look at the specs for the microprocessor in question. What is the output voltage. How much current?
Same with the LED. Get a data sheet for that LED and look at what voltage and current are required.

Finding data sheets ... there are a lot of places on the WWW to find data sheets. A personal favorite of mine is www.alldatasheet.com.

 

LEDs are current devices not voltage devices. What does that mean? It means you can drive them from any voltage at all, as long as you use a resistor to set the current.

 

LEDs are current devices not voltage devices. What does that mean? It means you can drive them from any voltage at all, as long as you use a resistor to set the current.

Basically true. If he only has 3 Volts white, blue, UV and such LEDs are a problem. They all like more than 3 Volts for full brightness.

 

How much Voltage will be present at the GPIO pin for a Microcontroller which has a Vcc(Input Supply voltage) of 3.3V ?
3.3V

Suppose I need to connect an LED at this GPIO what are the factors or calculations that I have to consider ?
LED forward voltage.
LED maximum current.
GPIO maximum current.

And, How much voltage should I apply to an LED to turn it on?
This information is supplied by manufacturer.

What should be its supply voltage?
LED forward voltage.

 

How much Voltage will be present at the GPIO pin for a Microcontroller which has a Vcc(Input Supply voltage) of 3.3V ?
3.3V

Suppose I need to connect an LED at this GPIO what are the factors or calculations that I have to consider ?
LED forward voltage.
LED maximum current.
GPIO maximum current.

And, How much voltage should I apply to an LED to turn it on?
This information is supplied by manufacturer.

What should be its supply voltage?
LED forward voltage.

DESIRED LED current. You don't have to run it at maximum. If the GPIO pin can only drive 5 mA you are limited to that, or use a buffer transistor. Can you drive the LED at 2 mA and get sufficient brightness? Try it.

 

How much Voltage will be present at the GPIO pin for a Microcontroller which has a Vcc(Input Supply voltage) of 3.3V ?
3.3V

Suppose I need to connect an LED at this GPIO what are the factors or calculations that I have to consider ?
LED forward voltage.
LED maximum current.
GPIO maximum current.

And, How much voltage should I apply to an LED to turn it on?
This information is supplied by manufacturer.

What should be its supply voltage?
LED forward voltage.

Crisp and clear. Thank you.