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I'm designing a PCB with a standard arduino ATMEGA328 DIP IC. Do I need to make a connection to the reset pin?

blarg
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  • You absolutely need one! What if you have to reset your processor but you can't detach from the power supply? – Stefa168 Jun 12 '15 at 17:26

2 Answers2

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"Atmel AVR042: AVR Hardware Design Considerations"

AVR reset connections

Ignacio Vazquez-Abrams
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  • +1 for the ref. “The reset line has an internal pull-up resistor, but if the environment is noisy it can be insufficient and reset can therefore occur sporadically.” So it seems one could possibly live without in “quiet” environments... – Edgar Bonet Jun 12 '15 at 15:52
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    Certainly. None of my prototypes use the above circuit, but my final products do. – Ignacio Vazquez-Abrams Jun 12 '15 at 15:58
  • I don't get the diode however, if you only connect a button. Can noise really cause it to enter high-voltage-programming-mode? – Gerben Jun 13 '15 at 12:53
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Yes, you do. The pin needs to be pulled up to Vcc via a pullup resistor - typically 10KΩ. Also, if you are using the Arduino bootloader and want to program via serial then this pin should be connected to your serial interface's DTR pin through a 100nF (typically) capacitor. It is also often desirable to provide a reset button which switches this pin to ground.

You should examine the Arduino Uno's schematics and use them as a reference.

Majenko
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