Hi Barry,

1) OK. You can always run some mod wires on the one you've got to verify before committing to new FR4.

2) Yes. At startup you set your dutycycle register so that you get a 50% dutycycle output. If pid_Out is positive you ADD it to the 50% value, if pid_Out is negative you subtract the ABSolute value of pid_Out from the 50% value.

3) Well, in locked antiphase mode it's not only when YOU reverse direction. If the speed setpoint is changed (even though it is still in the same direction) the PID filter will react to this sudden error and, depending on the tuning of the filter, do more or less violent things with the output to bring the actual speed back to the setpoint. This can in reality mean that the polarity of the average voltage applied to the motor is reversed, ending up in series with the EMF. I'm not saying it's GOING to be an actual problem, just be aware of it. Of course you can always clamp the output to either positive or negative IF it turns out to be an issue in the future.

In locked antiphase mode the full rail voltage is always applied across the motor (except during the dead time period). It's either applied in one polarity or the other.
* If the duty cycle is 50% and the motor is stationary and you measure the average voltage across the motor you'll read 0V.
* If you use a differential probe and look at the voltage with a 'scope you'll see voltage swing of +/- the rail voltage.
* If you measure the average voltage from either motor terminal to ground (still at 50% dutycycle, stationary motor) you'll measure half the rail voltage.
* If the dutycycle is 0% or 100% (don't do that you'll probably fry the high side driver) the voltage across the motor will obviously be + or - the full rail voltage.

/Henrik.