Simple exercise, push NO button and LED goes HI and after delay time goes LO, LED between D12 and GND. NO button between 5VDC and D7. D7 to gnd through 10k resistor w/ 100nF cap across the resistor(external pulldown instead of software)? What is this cap doing? Circuit works fine without the cap and resistor pulls down spurious inputs. The resistor I understand, but what is purpose of cap?
Removing both cap and resistor will cause D7 to trigger the LED to go HI. Putting the scope probe on D7 will pull it down and eliminate spurious inputs. Cap alone or resistor alone prevents spurious inputs on D7. Seems they used the belt and suspenders method of eliminating spurious inputs, unless I am missing something here.
No I was wrong. With cap alone, when button is pushed LED goes HI and does not time out. Code must believe the button is being held closed. Even more of a reason for me to question why the cap?