Disable auto-reset Mega 2560 on serial monitor open using 60 ohm resistor
A 22uF cap between reset and ground does work on my Mega 2560 - opening the serial monitor will not restart the program. However, the Mega is then not downloadable. Therefore, I grounded the cap thru a normally closed relay and connected its control to a digital output. I normally operate with the relay closed. When I want to download a new program I open the relay first. It works great :-)