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1  Using Arduino / General Electronics / Re: The ants come marching in (and release magic smoke) on: February 12, 2013, 08:11:49 am
Maybe the ant bridged the pins and died causing a faulty input/output logic that caused the high power device to be powered to long, overheat and melt solder. It could also have been dead some time but damp air absorbed into it's body made it conduct.
I have seen a working PC stored in the loft for a few weeks fail to boot properly when removed and powered on. The accumulated dust on the internals was fine when PC was used daily (probably overheated the thing slightly) but storage in the loft had allowed the dust to get damp and cause problems. A quick vacuum out and it started working again.

This is what I suspected - logic problem leading to overcurrent of a high power component.  I hadn't thought of absorption of moisture, but that is probably what  happened.  It seems like the ant have been in there a while since it is winter now, and I haven't seen any ants for months.  We did have a major ant problem in the summer.
2  Using Arduino / General Electronics / The ants come marching in (and release magic smoke) on: February 12, 2013, 12:01:25 am
This doesn't have anything to do with an Arduino, but I am wondering if anyone has a theory about what happened to the circuit board on my dishwasher.  The writeup is here:  https://sites.google.com/site/boschdishwasherrepair

Basically, it appears that ants shorted out pins on a microprocessor causing a major current surge and melting the solder off a large current carrying lead (not sure the exact component).  Can the body of an ant carry enough voltage to short circuit a microprocessor?  Thoughts?  Comments?

Dan
3  Using Arduino / Project Guidance / Broad concepts- Motor pwm and multiple servo control over xbee on: November 01, 2012, 12:31:17 pm
I need help understanding some concepts about wireless using xbee and using multiple "simultaneous" outputs.

My proposed project: Build an rc model aircraft carrier with a variety of working parts.

For remote control I am considering using xbee.  What I want is the ability to control multiple outputs (mostly servos) for things like elevators (4), ramps (4), catapults (4), crane, anchor, bow thruster (reversible motor), several different lighting schemes, and others that maybe I would add as the project progresses.  I am thinking I would put an arduino mega on the boat since as I understand there are up to 48 outputs.  I could also have a mega on the transmitter end to handle all the switches and buttons. What I don't know: it is possible to control 20+ outputs wirelessly.  I understand xbee has 8 digital outputs.  Does this mean that I could effectively only have 8 "channels" (if digital pin 0 on the transmitting xbee is set high then the receiving pin 10 on the mega for example is set high)   Or is there a way (multiplexing?) to say if pins 0 and 1 on xbee are high then, for example, pin 21 on the receiving mega is set high, and if pins 0 and 2 on the xbee are high then activate pin 22 on the mega, etc.  Or does it not work that way?

My second question has to do with operating these devices while running the motors (I have the motors hooked up to an H-bridge I made and am controlling with PWM).  Obviously I would want the portside and starboard motors along with the rudder servo to have priority. And it is not like all of the servos would operate at the same time.  In reality, probably only 1-2 would be operating at any one time.  But, for example, I would like to be able to keep the motors at a constant speed  and control the rudder (to keep the deck into the wind) while firing the catapult to launch the plane.  It seems like operating one of the peripheral devices might interfere with the motors or rudder or would the few milliseconds to set a pin high not really be noticeable?

Thank you for any suggestions or assistance in helping to understand these concepts.
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