I have a simple project that sends out a 4-bit message accross 4 output pins. the message changes when a button is pressed.
If the button state is 0 the pins read, starting at pin 0 to pin 3, (1100). When the button is pressed the states become (1001).
My question is, why would the IDE give me an error when I try uploading the program when all the LEDs are hooked up to the Uno board, BUT when I disconnect all the LEDs from ground the program successfully uploads???