Re: [Gumstix-users] Robostix ADC flakey power

[/<evin <kev...@ya...>]

Hi Dave,

I guess I will try and compensate for it in software.
I have done this before (2001) but I guess I did not realize how lucky I was
in my teams decision to purchase hardware (in all fairness I believe we paid
150-200$ for our PC/104 IO board):
http://www.cs.dartmouth.edu/~spl/Academic/ProgrammingProject/Fall2001/docs/LabyrinthMapperBrochure.pdf

LOL we had 7 gp2d12 and did not notice these issues!

Thank you for the help (and I will be looking into a subscription to SERVO
mag)!

BTW what are peoples thoughts on the $169 o-scope from www.hobbylab.us?

Regards,
Kevin


Dave Hylands wrote:
> 
> Hi Kevin,
> 
>> Following your advice and subsequent reading of the gp2d12 data sheet a
>> cap
>> is recommended (they say 4.7uf).  I had some 10uf caps lying around and
>> tried those.  No noticeable improvement.
> 
> Yeah - but the data sheet also doesn't mention the 400 ma
> instantaneous current spikes either.
> 
>> Why might I not be able to power either sensor independently of the
>> robostix
>> and still collect an analog reading?
> 
> There should be nothing wrong with having the sensor powered
> indepandantly of the robostix. You just need to make sure you have a
> common ground.
> 
> In fact, many of the guys doing the fire fighting bots, which often
> have a dozen of the GP2D12's on them, have a separate voltage
> regulator for each sensor, just because of their spikey current draws.
> 
> The August 2004 edition of Servo, in the "Ask Mr. Roboto" column has a
> really good discussion about the Sharp sensors along with some scope
> captures showing the current draws.
> 
> -- 
> Dave Hylands
> Vancouver, BC, Canada
> http://www.DaveHylands.com/
> 
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