I need to know how the LED light of a USB card reader that indicates the data transfer works?

Is it possible to create such a light using transistors and putting that circuit parallelly with a data cable connected to a USB storage drive?



In this diagram how that LED connected with the GPIO0 pin works?

I was talking about the light that blinks in this video.

https://drive.google.com/file/d/1odw-TqbCfqCP_JEQI6smA7dSSWmZ1QNp/view?usp=drive_link

 

The LED is controlled by software to show that the desired operation is working.

 

When the GPIO pin is at a logic high level (3.3V), current flows through the LED via a current-limiting resistor (R6 for the R&W LED).
Welcome to AAC!

 

Is it possible to create such a light using transistors and putting that circuit parallelly with a data cable connected to a USB storage drive?

No.

The light is lit by the software if the micro when it has verified that it has read valid data. Nothing external to the micro could do the same. Even if it was able to verify the data, there is no guarantee that the micro did the same.