I’ve been working on an arduino protoshield. It has been working fine until I added three resistors from pins 9, 10 and 11 to a multi color LED and then the other leg to GND. Now when I plug in the shield it shorts the Arduino. I pulled out my multimeter (which I’m only just learning to use) and found contuity from GND to 5V when not plugged into the Arduino. I looked hard and can’t find any solder bridge between these points as well as accidentally soldering to the wrong pads on the entire thing. Is it possible that two layers of the board came into contact inside the board?
Did you make any headway yet? I had a look at the Protoshield and there isn’t a lot that can go wrong in the area of pins 9-11. I’d investigate the area around the LED and see if the problem is there. Where did you connect the LED (BlueSMiRF header, power header, somewhere else)? It seems to me that this might be the culprit. I have never seen a case where a solder connection caused multiple layers to short together. Also, this is only a two sided board anyway, so you can see both layers. Good luck, and let us know how it turns out.
I just figured it out about 1/2 an hour ago, I think; it’s working properly at least.
I have 3 linear pots (and two normal pots) connected to it and all three were set at the least resistance point sucking all the power. At least that’s my theory. My understanding of these things is limited but in rapid development. I did scrape and push and run resistance tests across all sorts of areas to the board until it hit me that the sliding pots were just resistors and if they were wide open wouldn’t offer much resistance at all. If I understand this correctly, it would basically be like putting a wire between 5v and Gnd.
Does that make sense?
So I guess the real question is, should I be setting up my pots differently? I just have one pin to gnd, another to 5v and the third to an analog pin on the arduino.
As long as the center pin is to the arduino, that should not be a problem at all (unless the Arduino pin is driven high/low at startup before becoming an input).
Theatrus has it right. A common problem is connecting the power to the wiper (usually the middle connection) and then adjusting the pot until it gets near enough to the ground side to flame out. Sometimes the show can be pretty spectacular, a light show complete with smoke.
But, I was wondering where the LED’s from your first post were coming in. When I use them, I connect a resistor (330/470 ohm or so) from the Arduino pin to the LED’s anode and connect the LED cathode to ground. Setting the pin to “1” turns on the LED. Using a pot as a current limiting resistor is a bit of an overkill and could lead to exceeding the maximum current of the LED.
