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Subject: 
Re: Question on analog(). Negative voltage
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Wed, 5 Jun 1996 13:37:18 GMT
Original-From: 
Fred G. Martin <fredm@media.mit.eduSTOPSPAM>
Viewed: 
3606 times
  
> Last time, I learned that the values of analog() corresponds to the
> voltage between 0 and 5.  What if the signal to the analog port is
> a negative voltage.  For example, -2 volt ?  In that case, does that
> mean I have to use another formula or make some electronic circuit ?
> One application of this is to capture the signal from the speaker
> and then use the robot to recognize the signal.

DO NOT SEND NEGATIVE VOLTAGES INTO THE 6811, you will destroy the
analog input circuit.  Any voltage outside of the 0 to 5 v range is
hazardous, unless it is current-limited to a few milliamps.

> As for the Rug Warrior, it has such function.  For example 0 volt
> means analog()=128 and watever of negative voltage is analog()<128.
> Whatever of positive voltage is analog()>128.

Are you sure about this?  On page 49 of my copy, it states pretty
clearly that the input range is 0 to 5 v.

So anyhow you need a circuit to convert your desired input range to
the 0 to 5v range.  If your application is audio, you could just
rectify the signal to ignore the negative component.

-Fred



Message is in Reply To:
  Question on analog(). Negative voltage
 
Last time, I learned that the values of analog() corresponds to the voltage between 0 and 5. What if the signal to the analog port is a negative voltage. For example, -2 volt ? In that case, does that mean I have to use another formula or make some (...) (30 years ago, 5-Jun-96, to lugnet.robotics.handyboard)

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