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I am creating a simple robot that is controlled by an Arduino UNO, and given instructions by a button matrix.

One can press 4 buttons for Forward, Backward, Left and right on on the matrix array, which are translated into signals for a custom L293 module (PCB) attached to the UNO. The L293D module is powered by a desktop SMPS at the moment, which is connected to its 5V and 12V pins, while I power the UNO with USB power.

The problem I am facing is that motors don't move even when correct signal is given, which I have verified through Serial Monitor in the Arduino IDE. But they do move if I attach any of the 4 data pins to SMPS' ground line or just touch it with bare hands.

My knowledge of practical electronics is minimal and unsystematic, but I think it has something to do with common ground. I would like to know how I can resolve this problem and can I power both L293D and UNO from a single power source, such as a 12V battery, and if so, how?

Here is the schema of the setup (power sources not shown): Schema

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  • \$\begingroup\$ 1. The circuit cannot work because there is no power source connected in your artwork. 2. The vertical rails are not continuous over the full length. 3. Arduino is a controller not a power station. 4. Add a decent circuit diagram instead of clip art, nobody knows the pinouts of your devices from top of mind. 5. I don't see any extra decoupling, which is interesting with so much inductive loads added. \$\endgroup\$ – jippie Mar 14 '15 at 13:57
  • \$\begingroup\$ Actually the schematic does not show power sources. As I mentioned The L293 is connected to a desktop SMPS (for 5V and 12V) and Arduino to a laptop. \$\endgroup\$ – c.sh Mar 14 '15 at 15:00
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if i was you i would leave the motors where there at and just use 4 transistors in connection with the motors and connect 2 or 3 9v in place with transistor at this point you should be using your multimeter to check that your power source is being regulated to each individual motor and the arduino as well tho the arduino can be power thru VIN 12v if im not mistaking, then leave the rest to the code, "allow electron flow thru pin listed as -int- OUTPUT and using this method u should be able to control the motors Dir "use a hbridge connection using only wires (like a DPDT Switch typical internal connection)unless you can buy and setup the use of a actual IC chip

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