This project is about building a Line following robot but it non programmable so micro-controllers are not allowed. To sense the line we are using LED to reflect light and to sense the reflection we are using LDR. A variable resistor to control the the sensitivity of the LDR. Also resistors are used to compare the values of the LDR resistor and fixed resistor values. To do this we are using LM324 comparator. There are three sensors, two to detect the line and one to detect the background. This is because half of the track is black black background and the other half is white background. Logic gates are used to steer the robot left and right. From the logic gates the connection goes to h bridge L293dne. I want to know how to connect the wires from logic gates to the H bridge. I am confused because there is one output from the logic gate to the one half of the h bridge to control one motor. But the H bridge takes two input. Also how do i connect to 'enable' H bridge input. Outputs are two Dc motors 4 AA batteries are in series to power the robot. With this post i have attached a circuit diagram with the layout of the L293dne H bridge. Help would be much appreciated.

 

The circuit diagram and the L293dne layout

 

You didn't read far enough in the blog you took your first picture from.
http://developeraspirations.wordpress.com/2010/04/19/l293dne-h-bridge/

Go back and read the last two paragraphs in the text.


The L293 is a very old chip, and drops a lot of voltage across it. You may have a problem with your motors speed. There is a newer pin for pin replacement, the SN754410ne. Here is a link to it and it may give you more help understanding the L293 also. http://www.hobbyengineering.com/appHBridge1A.html