Arduino Auto Reset: Disable an Enable at run time

Modern Arduinos have a Auto Reset circuit: There is a 0.1uF capacitor between the #DTR (not DTR) pin of the USB/UART chip and the reset pin of the Atmega.

This circuit resets the Atmega microcontroller each time a new serial connection is established, it is possible in this way to upload new sketches at any time. THe new connection resets the microcontroller and then the new firmware can be uploaded.

The drawback of this circuit is that it is not possible to support services that must survive new serial connections.

For example I am designing a Home Automation unit controlling some lights based on Arduino Nano. The lights can be turned on and off using some buttons, the state can be queried and changed using a serial connection.

I have designed the following circuit to Enable and Disable auto-reset using an output pin of the Arduino itself or from another controller.