Help. LCD Stopped working when DC Motor is connected

I'm building an alarm clock on a motorized vehicle. Vehicle moves and buzzer sounds when alarm goes off.

I programmed the clock and it is displayed on an Arduino LCD. The display and buzzer work fine.

When I add the two DC motors into the mix, they spin when the alarm goes off, however, the LCD goes fuzzy simultaneously.

I'm using an Arduino Rev3 Motor Shield.

The whole project is powered by 4 AA batteries (6V). I though maybe it was not enough voltage so I tried a 9V and with that when the alarm sounds the LCD resets itself.

Any thoughts guys and gals?? This is a school project due in a week!

Any thoughts guys and gals?? This is a school project due in a week!

You could try searching this forum for other similar cases. The same problem crops up with relays, solenoids, and anything else that's basically a coil of wire.

The search function provided with this forum software is slightly better than useless. Try a Google search using this syntax: --> search phrase site:arduino.cc

Don

How do you connect the motor ? Seems that you got an "Out-of-Power"-Error ;)

I have the motor leads going into the Motor Shield channels. The Arduino board is powered by a 9v battery and the LCD is powered by a separate 9V battery.

I also tried connecting a capacitor across Vcc to ground on the board to help eliminate a drop in current when the motors turn on but still no luck.

Thanks for the tip Don I found some similar situations on the forum tried a few things people have done but still getting the same error.

but still getting the same error.

Try to connect at least the motor power with an own power supply/batterie

You have a complex problem here.

I am not sure what you mean by "the LCD is powered by a separate 9V battery" because you would have to be regulating the LCD supply to 5V for it to work, presuming it to be a common 1602-type display which requires 5V; not 6V and preferably not 4.5V though that might just work.

You need to run the motor shield supply from 6V, four AA should be OK, but nothing else runs from this supply.

Now powering the Arduino gets a trifle tricky. You need either 7V to the regulator - 9V will do but the tiny 9V common sort of batteries will probably not last too long - or 4.5V (three AA batteries) directly to Vcc without the regulator. If you do the latter, you can run the LCD backlight from it as well, so you could use a little 9V battery and regulator to power the LCD (or you might get away with 4.5V given some difficulty with the contrast).

That sounds like three separate batteries to provide for the three different requirements of those parts, but that may be the best way to have it work for the present.

Sorry my explanation was a bit confusing. I have the the motor shield and the the Arduino board running on two different power supplies and the Arduino supplies the LCD with power. I'm starting to think that maybe its a software issue rather than hardware. Because the backlight of the LCD remains on even though the display goes blank.

Because the backlight of the LCD remains on even though the display goes blank.

The backlight is a completely separate system from the LCD.

Don

floresta: The backlight is a completely separate system from the LCD.

The backlight is less critical in terms of the voltage, and immune to transients.

As is so often said, I think we will need a photograph of the "fuzzy" LCD, need a description of whether it recovers correctly afterward, and really, a photograph overall. Attached here (icon to the left of the "world") in a reasonable resolution (1024 by 768 maximum), perfectly focused.

And presumably, this problem happens only when the motors are actually connected, but not when not connected but the same code?

you need to add a capacitor across the motor

I think the problem has probably been resolved by now.

Don