I'm running a stepper motor using a dual H bridge chip. I've previously done this and it worked fine. In order to get enough power, I did kind of a two stage power supply. On my breadboard, I connected one pair of rails to the highest wall wart I could find: 7.5V, 1A. I ran the chip's motor supply pin from that. Then I plugged a second, small power supply into that rail and ran the Arduino (an NG) from that supply.
More recently, I needed a little more power. I realized two things:
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I have a breadboard power supply unit I built myself. It's kind of big to use on my work surface, which is why I didn't think of it before. I can dial in any voltage from ~3 to ~36V. Not sure what it will supply but definitely more than an amp.
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Why am I doing a two stage power supply? Why not run the entire thing at, say, 9V and plug the Arduino (power supply socket) directly from that?
So I did that. It seemed to work with no problems....until suddenly I couldn't communicate with the Arduino anymore. The error:
avrdude: verification error, first mismatch at byte 0x0000
0x0c != 0x00
avrdude: verification error; content mismatch
I believe this is a missing bootloader problem. My questions are: Was this some other error or did I overpower the thing? How should I have done this? In particular, how can I run the Arduino and the stepper motor from wall power (I need it running 24x7)? Is there an example circuit?
It looks like even in the best case I need to buy/build a programmer to put the bootloader back on. (Worst case, could the chip or board be toast?) Given that cost and the fact that this is an NG, I'll probably just buy a new "bare bones" unit. But I don't want to do that until I know I'm not going to instantly fry it.