On 2 Jun 2010, at 21:38, James Bensley wrote:
As another test I used some digital inputs, when I press the left button "A IS ON" is displayed on the LCD, when I press the right button "B IS ON" is display, even though you can't make out the text, you can see in this video that just being near the button makes the Arduino sense enough voltage to indicate the button is pressed and display some text...
http://www.youtube.com/watch?v=jKuIDsq0WIQ
OMGWTFBBQ?
I have forgotten how I wired that pot but I ripped it all apart and started over with this small test but the problem still persists?
Is interference really that big a deal on these small circuits? To answer your question, it is powered off of a front USB socket on my PC, but I plugged it in the back and got the same result. I also tried unplugging all other USB devices, turning off my monitors and speakers to that just the computer was on giving the Arduino power but it is still going mad for EMI.
I turned my PC off and the main power socket so everything in the room went off, and ran the Arduino off of my laptop so it was using the laptop battery, same result. I used a 9v batter, same result!
If my Arduino is this susceptible to EMI its pretty much useless.
I dont think thats EMI.
Arduinos, like all machines, are susceptible to EMI, however in my experience, the only thing Ive manage to make it 'go wrong' on an arduino due to EMI is when I had it sitting on *top* of my Yeasu FT897 which was transmitting. I think the results of EMI upon an arduino would begin with the USB/Serial communication dropping out, so if you print lots (like an * every loop) and play and if you find it drops out continually (for several seconds as the chip fecks up) thats a good sign of EMI.
Having done a fair bit of LCD work (a few years back) I think what you have there is some other circuit or software issue - either you have a circuit issue (bad connection) or you are not sending exactly the right commands to the system.
The other thing to consider is whether the LCD is drawing too much power from the Arduino - You may want to consider powering the board's backlight etc seperatly instead of through the arduino, and seeing if that affects it. The other possibility is that the LCD display is having a dodgy effect on the ground supply.
Also, powering your Arduino from a power source instead of via USB is a possibility because again, your computer might be giving dodgy ground (althought that is very unlikley)
JT