Connect GND and AGND?

[Heinz Hummel]

Hello,

at https://books.google.de/books?id=Udu6BQAAQBAJ&pg=PA344&lpg=PA344&dq=beaglebone+adc+op+amp&source=bl&ots=CZagSBqMui&sig=cLXCgstuc51TzoBRzMzB81RcJyU&hl=de&sa=X&ved=0ahUKEwjZ6-LovKTSAhXJXBQKHfktBio4ChDoAQhJMAk#v=onepage&q=beaglebone%20adc%20op%20amp&f=false a wiring scheme for the analog inputs is described which protects the BBB/BBG from overvoltage.

Amazingly they connect AGND and GND with each other. Is this really a good idea?

Thanks!

[John Syne]

Well, at some point they are always connected. What you want is for them to connect only at one point and that point should be closest to the power source. Think of a star connection, with the center of the star as the reference ground point. What you don’t what is digital signals flowing through the analog ground and that occurs when you connect AGND to DGND at more than one point. 

Regards,

John

Thanks!

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[Heinz Hummel]

2017-02-23 7:55 GMT+01:00 John Syne <john...@gmail.com>:

Well, at some point they are always connected. What you want is for them to connect only at one point and that point should be closest to the power source. Think of a star connection, with the center of the star as the reference ground point. What you don’t what is digital signals flowing through the analog ground and that occurs when you connect AGND to DGND at more than one point. 

So when I understand this correctly: in layout of a board they should be connected with each other as close as possible to the BBB/BBG expansion header connector?

[roberts...@yahoo.com]

--------------------------------------------
On Thu, 2/23/17, John Syne <john...@gmail.com> wrote:

Subject: Re: [beagleboard] Connect GND and AGND?
To: beagl...@googlegroups.com
Date: Thursday, February 23, 2017, 8:55 AM

On Feb 22, 2017, at 10:14 PM, Heinz
Hummel <heinz.h...@gmail.com>
wrote:
Hello,
at https://books.google.de/books?id=Udu6BQAAQBAJ&pg=PA344&lpg=PA344&dq=beaglebone+adc+op+amp&source=bl&ots=CZagSBqMui&sig=cLXCgstuc51TzoBRzMzB81RcJyU&hl=de&sa=X&ved=0ahUKEwjZ6-LovKTSAhXJXBQKHfktBio4ChDoAQhJMAk#v=onepage&q=beaglebone%20adc%20op%20amp&f=false
a wiring scheme for the analog inputs is described which
protects the BBB/BBG from overvoltage.
Amazingly they connect AGND and GND
with each other. Is this really a good

idea?Well, at some point they

are always connected. What you want is for them to connect
only at one point and that point should be closest to the
power source. Think of a star connection, with the center of
the star as the reference ground point. What you don’t
what is digital signals flowing through the analog ground
and that occurs when you connect AGND to DGND at more than
one point. 

Regards,John

Thanks!




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onducerea partidului comunist a devenit in Romania in perioada regimului Ceausescu o casta politica fiind controlata de familia Ceausescu prin intermediul unei grupari de activisti. in 1987 partidul numara 3 6 milioane de membri in marea lor majoritate luptand sa supravietuiasca in conditii grele de munca si de viata. in martie 1989 gratie unor uriase eforturi materiale Romania si-a achitat datoria externa. Zecile de reorganizari de posturi la nivelul conducerii superioare urmareau de fapt punerea intregii

[John Syne]

As close as possible to the power source GND. So if you intend to use the barrel connector to power the board, the GND and AGND should connect at the barrel connector GND pin, or if you use the expansion connector to power the board, then connect GND and AGND at a single GND pin on the expansion connector. I does not matter that several GND pins are connected to the GND plane. I hope this helps. 

Regards,

John

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[woody...@yahoo.com]

--------------------------------------------
On Thu, 2/23/17, John Syne <john...@gmail.com> wrote:

Subject: Re: [beagleboard] Connect GND and AGND?
To: beagl...@googlegroups.com

Date: Thursday, February 23, 2017, 9:33 PM

To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/E32D58CB-DFA6-4A84-8291-4323E6E7316D%40gmail.com.

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stfel au fost incheiate o Conventia comerciala pe termen de 10 ani cu \ustro-Ungaria si un act similar cu Rusia prin care se profita insa de catre tarile are faceau parte din Alianta celor trei imparati Rusia Austro-Ungaria si Sermania de pozitia strategica favorabila a Romaniei. Chiar daca unele actiuni comerciale erau dezavantajoase aducand grave prejudicii economiei romanesti ile reprezentau totusi un castig in plan politic fiind un pas spre independenta.

[Heinz Hummel]

This helps - thanks John!​