I have two major projects that I have completed using an Arduino Uno. One is a data logger using an Uno, Sparkfun's sdsheild and a custom PCB for connectors. The other is a pet feeder using an Uno, DS1037 clock, servo, and photo sensor. In developing the data logger, I was successfully implementing my code until one time nothing worked. I finally realized I had to press the reset button on the Arduino after I moved it from the computer to the data recording location powered by a wall plug. Likewise, the pet feeder has been working for months by simply plugging it into the wall and the program would begin. Now, after some modifications, including adding the clock, it now requires me to press the reset button after I plug it in. That's not an issue when I plug it into the computer's USB port since when I bring up the serial monitor, it automatically sends a reset command.
My question is this - is it a surprise that I need to reset it every time it's plugged in to the wall or is there some command I'm missing in my sketch that would do it? Why didn't I need to press the reset before and now I do?
I'll include any parts of the code needed for the answer if requested.
Thanks for your effort!
Doug