There should be dots at the junctions between the 10K and 100K resistors.

You're right, I slipped up this time!

 

What does the L9100 driver do when both direction inputs go high at the same time??Now that I can see a circuit schematic it is clear that is what is happening now.

 

What does the L9100 driver do when both direction inputs go high at the same time??Now that I can see a circuit schematic it is clear that is what is happening now.

When both inputs are either high or low the chip goes into "Apply the Brakes" mode, as they term it, so I expect either both upper, OR both lower transistors/MOSFET's are turned on.

 

When both inputs are either high or low the chip goes into "Apply the Brakes" mode, as they term it, so I expect either both upper, OR both lower transistors/MOSFET's are turned on.

That appears to be what is happening when neither sensor is activared, based on the circuit in post #19. If neither transistor is conducting because neither sensor is activated, then both outputs are high.

 

Yes, but if the circuit is re-arranged as in my post #19, when a button is held closed, Q5 (or Q6) pulls an input low, so pulling low one or other of the driver outputs and allowing the motor to turn.

 

Ok, here's what I mean. I've drawn all the voltages as if connected to the same 5V supply, but if you wish to run the diode from a lower voltage, don't forget the resistor! Just make sure that it's a suitable value.

View attachment 314293

EDIT: Image corrected!

Thank you for this!

Although I am somewhat confused by this design. To my understanding the 5V running through the 1k Ohm resistor would result in almost no voltage flowing to the IA or IB pins. Also when the button is pushed down and the opto npn transistor is not active, the Q1 npn opens therefore setting the IB voltage to 0V when it shouldn't resulting in the motor not spinning. Please let me know if I am understanding this wrong.

 

Do we actually know the input versus output current/voltage relationships for this driver device?? Certainly that may have a great effect on the response. I have not looked up the data sheets on the L9100 driver, but the requirements should have been examined and verified as part of the design process.

 

Thank you for this!

Although I am somewhat confused by this design. To my understanding the 5V running through the 1k Ohm resistor would result in almost no voltage flowing to the IA or IB pins. Also when the button is pushed down and the opto npn transistor is not active, the Q1 npn opens therefore setting the IB voltage to 0V when it shouldn't resulting in the motor not spinning. Please let me know if I am understanding this wrong.

With my circuit attached, and the inputs IA & IB connected to the collectors of the transistors Q5 & Q6, and no buttons pressed, the voltage on both inputs should be pulled High by the 1k resistors to approximately+5v, and the motor should be stopped.
If either buttons is pressed, the corresponding input, either IA or IB should be pulled Low to nearly 0V, and the motor should rotate!

 

With my circuit attached, and the inputs IA & IB connected to the collectors of the transistors Q5 & Q6, and no buttons pressed, the voltage on both inputs should be pulled High by the 1k resistors to approximately+5v, and the motor should be stopped.
If either buttons is pressed, the corresponding input, either IA or IB should be pulled Low to nearly 0V, and the motor should rotate!

Ok thanks! I understand now, I appreciate the help!

 

Ok thanks! I understand now, I appreciate the help!

Is it working?