On Thu, Dec 27, 2007 at 09:34:37PM -0500, Nick Holland wrote:
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> I've got a little project I'm working on here.
> It involves stuffing a computer in a donation box with a
> money detector, so every time someone tosses money in the box,
> it plays an MP3 file.
> 
 
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> However, this is the first time I've ever done an OpenBSD system
> that wasn't going to be attached to some kind of network for
> (hopefully) years at a time.  In fact, hopefully, it will NEVER
> be attached to a network.  And, while I got a 1G CF device, I
> could imagine doing something stupid and having it slowly fill
> the CF media and six months from now getting a call saying, "It
> died.  Come fix it", and since it will be in another country and
> probably a ten hour drive away, I'd like to avoid that. :)
> Once this thing is deployed, I won't have access to it at all,
> so I'll have no ability to spot a potential problem or fix it.
 
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> What have I forgotten?  Is there anything else I can do to avoid
> slapping my forehead and saying, "D'oh! Forgot to ..." before I
> ship it out fully detached?  The good news is I'm pretty sure
> there is at least one OpenBSD developer near-by, but that's just
> all the more reason to make sure I don't screw it up, I'll never
> live it down. :)

I'd wire in a hardware-type heartbeat detector that will power-cycle the
computer if it stops working.  I'd have a door over the money slot
powered by the computer so that it only accepts money when its working.
You could have a "Please wait" light to be lit during the reboot.

Or, you could just rewire an MP3 player to play a tune when it is
powered on, then just hook the money-detector to the power switch.
Money turns it on, a timer just longer than the tune turns it off.  No
computer needed (just a 556-dual-555 timer IC and some spare parts).

What about a built-in modem set up to allow a login.  Then if something
_does_ go wrong, you can ask the user to provide a phone line to the box
and you with the phone number.  With this, you can fix or even upgrade
the box over the phone.  Add a hardware cycle-counter; if the heartbeat
causes a reboot and the cycle counter doesn't get reset, it lights a
"please call for service" light.

Doug.