I am working through a series of lessons on using the Raspberry Pi 3 Model B with the Osoyoo Raspberry Pi Starter Kit. The first lesson is to build a simple circuit in which GPIO #17 is used to power an LED off and on by toggling the pin low to turn the LED off and high to turn the LED on. A 200 ohm resister is part of the circuit. The lesson is available on the Osoyoo web site, Raspberry Pi Starter Kit Lesson 3: Prepare GPIO Tool-WiringPi Utility.
For the program itself I used C with the wiringPi library to access the GPIO board.
The first time I did the circuit and the program the LED would turn on when the pin was low and turn off when the pin was high. The LED was also very dim and the lit phase was difficult to see without cupping my hand around the LED to make the lighting more visible.
I retried that circuit and now the LED is much brighter and I had to change the program so that the LED is lit when the pin is high and the LED is off when the pin is low. This is the way it is actually supposed to work with the high pin providing 3.3v to the LED circuit to light the LED when the pin is set to high.
So now I am curious about the first circuit that I did and where my mistake was.
I assume that I had some kind of LED polarity problem along with some mistake in the circuit so that when the pin was high the LED was driven to be off. And I assume that when the LED was dimly lit by the pin being low it was due to induced currents with the pin floating because I did not have a pull down resistor to zero it out.
Can someone tell me an LED with 200 ohm resistor circuit that would give the previous behavior?