According to Texas Instruments, the L293D has the following setup
Enable 1, 2 Driver Channels (5V) [ u ] Chip Power (5V) Driver Input 1 [ ] Driver Input 4 Driver Output 1 [ ] Driver Output 4 Ground 1 [ ] Ground 4 Ground 2 [ ] Ground 3 Driver Output 2 [ ] Driver Output 3 Driver Input 2 [ ] Driver Input 3 Motor Power (12V) [ ] Enable 3, 4 Driver Channels (5V)
Where the u in the middle top represents the divet present on the top of the motor driver to tell which side is "up."
For my project specifically, I will strictly only be needing the left side motor control logic (1, 2) and since I am not running a DC stepper motor, I will only run the following two states (i.e. I want output 1 to always be the +12V and output 2 to behave as the ground, or for no current to be flowing at all):
I) [OFF] Input 1: Low | Input 2: Low II) [ON] Input 1: High | Input 2: Low
Now according to the tutorial I am following, I should just ground 1 and 2 back to the Pi. However, my concern is that that would cause a problem because the motor powering circuit is powered by a 12V supply. Hence, should I ground 1 and 2 back to the Pi (bottom)? or Back to the Ground for the 12V circuit? (at the top).
Thank you and much love!