I'm a little confused here and I hope that you can help me with this. On the main page it says that the IO pins of the Leonardo operate at +5V. I'm using many of these on my board and one thing I find confusing:
I've connected several IO-pins to a motor controller, one to a led and some others to a BT chip (HC05).
Now, I measure +5V on the L293D, thats good. But I only measure 2,75V on the led. How is it possible that I do not burn the LED when setting the pin to high? It should apply 5V and thus the led should be fried, right? Instead I measure 2,75V and the led is working. Wouldn't I need a resistor to operate the led?
Besides my curiosity, I'm asking since I want to bring the BT device to the at mode with the key pin. This pin needs 3,3V and not 5V. I do not want to try to just connect it and set the level to high, since I'm afraid that it could burn the chip...
Maybe you can help me with this supposedly simple question.