The following chip seems to be acting funny.
I have one DC motor hooked up to 1Y and 2Y and the other to 3Y and 4Y.
Could the behavior be because I connected the VCC1 (logic supply voltage) and 1,2EN and 3,4EN all together? NB. No resistor between them either (see page 6 of link). What might happen?
The weird behavior is the following:
When driving a DC motor in one direction (1A = 5V, 2A =0V), I'd expect 1Y to be VCC2 (output supply voltage) and 2Y to be 0V. Instead with a VCC2 of 9V, 1Y is around 7V and 2Y is over 1V. Making the voltage drop between the DC motors leads only 7-1 = 6V. What is happening here?
When activating two motors at the same time. They start to drive as normally and then slow down to a stop and twitch. This might be a software issue, but I'm not sure...
Also is it normal that the inputs of the H-bridge chip are floating values. Up to 1.3V-ish if I don't hook them up to the controller and set them to zero from there. I would expect them to take the 0 from ground
Finally, what is the purpose of all the diodes on the page 6 graph? I have the outputs hooked up directly to the DC motor.
Page 6 graph: