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Topic: gnd question (Read 797 times) previous topic - next topic


Mar 03, 2013, 10:24 am Last Edit: Mar 03, 2013, 11:11 am by Rohitchampion Reason: 1
Is there any difference between analog ground and digital ground?? If yes what? if no why there are two grounds??
How can i decide which one to use??
I am asking about ATmega328P.


With what chip ?
The ATmega328P ? or with a radio chip ?

Normally both grounds are connected to the ground layer of a pcb board.
The analog power supply (The 5V or 3.3V) is sometimes filtered to reduce ADC noise.
However, there is more to it.
I know that TI has written (difficult to understand) documents about it, but I can't find it right now.


"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

Nick Gammon

Mar 04, 2013, 05:20 am Last Edit: Mar 04, 2013, 05:45 am by Nick Gammon Reason: 1
Wow, 22 million hits. That's more than my pages get. :)
Please post technical questions on the forum, not by personal message. Thanks!

More info:


Try this article.

I have a link to a very good TI article also somewhere, not sure where I saved i.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


Often on designs using analog I/O there is a separate ground used for the analog signals that does tie to the main system ground. The purpose is to prevent electrical current from flowing in the analog ground path and corrupting (adding noise) to the analog signals being brought back to or going out of the system. I have worked with Plasma cutting  and welding systems where this was very important because noise in the analog circuits could affect machine motion and produce quality problems with welds.

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