BC2 with Basic Motor Control

I have basic motor control working.  Motor Port 2 has some issue in the forward direction.  Looking at the pin on a scope shows the waveform, only at a few hundred mVolts.  I suspect there is a short to ground somewhere but I have not spent the time to look for it.  The other 3 Motor Ports work so I moved on for now to testing and driver development. 

When I first started testing, the PWM frequency was 20KHz, but on the scope it did not seem as though LB1836M motor driver could handle it.  I eventually lowered the PWM frequency to 5KHz, which seemed to work better.  I have read where Lego is using 1150Hz.  After finishing some driver cleanup, I am going back to retest the PWM frequency and generate documentation for no load motor conditions.  Just so I have it for future reference.

Here is a video that shows the basic driver going forward and reverse.  The motor starts at 100% and then slows down 5% every second.  It is actually easier to hear the change than see it.  This particular MOC I use at shows for customer interaction.  I have the Android App (modified for show use) running on a small tablet and the customers, mostly kids, can rotate the turret left or right and then fire the cannon.  It also has a clear front so you can watch the large (multiple gears) gear train work.  Because the gear train is so large, there is a large amount of the slop and slip in it.  This slop was always obvious when it changed directions in that you could hear the motor turning but the turret was not moving.  Then once the gears caught up it would move in the new direction.  I suspect this is also happening even when going in the same direction.  As the motor slows down in small steps, the gear train takes time to catch up.  I need to run this test by increasing the motor speed and see what happens.