[En-Nut-Discussion] ground difference

[Lars Andersson]

> -----Original Message-----
> From: en-nut-discussion-bounces at egnite.de 
> [mailto:en-nut-discussion-bounces at egnite.de] On Behalf Of emjay
> Sent: Tuesday, 17 January, 2006 11:24
> To: en-nut-discussion at egnite.de
> Subject: [En-Nut-Discussion] ground difference
> 
> 
> i have an ethernut 1.3 supplied by 12 V
> 
> why is there a diffenrence between the grounds (GND and 
> supply ground) 
> of ~0.8V?

Because there is diode in between there.
The diode is part of a rectifier bridge so you can use
AC feed, it also prevents some stupid mistakes ;-)
 
> how can i realize a measurement (INT0) of an external 
> rectangle signal 
> 0-5V, without connecting (shortening) the grounds (GND and ground of 
> rect.=supply ground)?

If your power supply is 12V DC (it probably is) I think you *should* 
connect your grounds together. It is the easiest solution to 
your problem. 

// Lars H. Andersson
 
> 
> thx emjay
> 
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