Hello. I'm a beginner with this and I'm facing quite a few problems when attaching my motor shield with arduino uno..im currently making an obstacle avoiding robot and the 4 motors with the shield and also powering the arduino (with the external 9v supply to the shield) from the shield.
1st problem is that the program only runs when my usb cable is attached with arduino.. When the usb is removed the program stops working and everything stops. It doesn't work of the external power supply (9v battery)
2nd problem is that the yellow led starts flickering countinuosly on the contrary the on led of the arduino is stable.
I tried to search for solutions on the forum and found a chat from someone with a similar problem to mine. But replies and solutions given to hime were all deleted for somd reason.
Please I need help urgently to complete this project. I am using the L293D motor driver.
Your 9V battery is probably dead and even if it were not dead, it probably will not be able to supply enough current for Four motors and the UNO will stop
Remove the Motpr Shield from UNO. Upload the blinking sketch from the IDE Examples. Disconnect the USB Cable from PC. Connect 9V Battery using the Jack with UNO. Is the L (built-in LED of UNO) blinking?
Is it a small PP9 battery? Then no chance of it powering your motors - your USB power easily delivers twice the current than such a battery. Use a wall power supply or if you must use batteries 2s LiPo or 4-6s AA alkaline.
That driver is not the best thing around, it will lose about 3V (burnt as heat) when driving both legs of the motor. I suggest you get one that has MOSFET outputs. This heat loss is battery power you will never be able to use. You will get that back with a MOSFET output device.