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106  Using Arduino / Installation & Troubleshooting / When you burn out one pin... on: July 02, 2012, 01:38:53 am
I was working with an Arduino clone (Osep) controlling an electric pump, when I accidentally fried digital pin 9.  It read zero volts no matter what I did.  Since I needed to use PWM, I switched to pin 10 and continued on.  After I got everything working OK, I noticed the motor would start briefly during program upload, and also whenever I opened the serial monitor.  I tried a 10K resistor between pin 10 and ground, but it didn't change anything.  I was new enough to the Arduino that I just assumed this was normal behavior. 

Eventually I got tired of disconnecting the motor every time I wanted to use the serial monitor, so I started investigating.  I found there was .35 volts on pin 10 even when it was set to LOW!  Here's the strange part - the motor didn't run all the time (as one would expect) because this model has a brake functon that activates when the voltage is below .4 volts.

Moral:  When you burn out a pin, get out your voltmeter and check the other pins!  Happy troubleshooting!

107  Using Arduino / Programming Questions / Re: Tracking Distance on one Axis with an Accelerometer on: June 27, 2012, 03:30:47 pm
Unfortunately, once the potato exits the barrel it will basically be in free-fall until it hits something. During free-fall, the accelerometer will experience "weightlessness" and should read zero. Not sure how to measure flight distance with an accelerometer. In the Olympics, they just walk over to the javelin and measure the distance it was thrown...
108  Community / Bar Sport / Re: Password restriction stories? on: June 26, 2012, 10:23:18 pm
Here's my password restriction story...and my solution.  I have been using this system for 3 years now, and it works great.
109  Development / Suggestions for the Arduino Project / Re: integer values for HIGH and LOW on: June 26, 2012, 12:37:26 pm
Thank you all for the responses, especially the one about all non-zero values .  Looks like experienced people already know such things, which is to my point that beginners should be able to learn about it by reading it in the reference documentation. 
110  Development / Suggestions for the Arduino Project / integer values for HIGH and LOW on: June 25, 2012, 11:55:06 pm
I just discovered (by accident) that 1 and 0 work the same as HIGH and LOW for pin output values. I wish I had known this earlier! Please consider mentioning this in the online reference. Using integers allows you to set pin output values with the result of a calculation - very handy in certain situations. You can even write statements like this:
digitalWrite(pin, a > b ? 1 : 0);
Thanks for considering my suggestion, and thanks for creating the Arduino!
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