[Lvlug] arduino question

[Keith Erekson]

I slapped the meter on the garage door opener button; it idles at 8V
(seems like an odd choice) and dips drastically when the motor runs.
Maybe it's 9V nominal, or was at one point anyway. This thing is pretty
old-school. I think might be older than I am.

If TTL levels were enough to trip the garage door's relay, the Arduino
should be able to drive it, right? Maybe with a diode in front of it, so
that the 8V on the line doesn't cook it?

Of course, at the point where you're worried about damaging your
hardware, I guess the $2 relay is a worthwhile investment.

On a related note: has anyone played with 1-wire on the Arduino? I
currently have a 1-wire temp chip (Maxim DS1820?) in the garage (and a
few in other places), on a crappy 1-wire to serial adapter. I'd love to
replace it with the Arduino. A quick google seems to indicate that it's
possible (and that people have trouble with it).

I also ordered some magnetic reed switches yesterday. The idea is to
have something alert me when I leave the garage door open after midnight
or so, and let me close it without going "all the way" to the garage, or
be able to let people into my garage remotely without giving them the
PIN for it, etc. Has anyone attempted something like this? Any wisdom to
share?

-Keith

Mark Stanley wrote:
> Hi Keith,
>
> It is a very slim possibility that you could connect your Arduino directly to 
> the button contacts.  You would have to make certain that the garage door 
> controller uses a TTL input for the button.
>
> It's pretty risky if you are not certain or don't know what I mean by TTL.  If 
> you do know what I am talking about then you need to know that a port pin can 
> source 60mA and sink 50mA.
>
> If you use a relay then can you avoid all the problems with trying to figure it 
> out.
>
> -Mark Stanley
>
> On Tuesday 23 March 2010 01:28:41 pm Keith Erekson wrote:
>   
>> I'm hoping to do some dabbling in home automation, specifically
>> concerning my garage door. I was originally considering bit-banging a
>> parallel port, but this seems like a perfect opportunity to play with an
>> Arduino.
>>
>> I believe there are a handful or Arduino enthusiasts on this list... so,
>> my newb question: are any of the ports on a Duemilanove able to close a
>> circuit? Or do I need an external relay for that? (e.g., to emulate
>> pushing the garage door open/close button.)
>>
>> ~Keith
>>
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>
>