Suggestion for Separate Invert Pins on Dual MC33926 Carrier

In preparation of comparing the current requirements between the two pulsing techniques, pulse/brake vs pulse/coast (as discussed with Ben in this thread), I wanted to understand the various pins on your dual MC33926 board. One pin which puzzled me was the “INV” (invert) pin. I couldn’t imagine why one would want to reverse the logic on the direction pins but then I realized the invert pin would allow pulse/coast control with two I/O pins by pulling one “IN” pin high and the other “IN” low, the invert pin could be used to set the direction of the motor and the “D2” pin could be pulsed with the PWM signal.

This two I/O pin control (using pulse/coast) would work with your single MC33926 board but by joining the two invert pins together on the dual carrier board, individual motor control with the invert pin is lost.

I hope Pololu will bring out the two invert lines separately in a future revision of the dual carrier board. IMO, access to the individual invert lines would be more helpful than having access to the “D1” pins (I haven’t figured out how these are useful yet).

As requested by Ben, I plan to post the results of my investigation into pulse/brake vs pulse/coast, but I wanted to get this request for a change in the Dual MC33926 Carrier Board as soon as possible. As part of the revision, possible jumper positions could be added next to the “IN1” and “IN2” pins to allow one to be pulled high and the other to be pulled low. IMO, having the option to control the MC33926 with two I/O pins in either pulse/brake or pulse/coast mode would be a useful addition to Dual Carrier Board.

I was going to suggest the two I/O pin alternative using the invert pin be mentioned on your single MC33926 board page, but I see it already is listed as a control option. This makes me wonder why this control option wasn’t preserved on the dual carrier board.


Hi, Duane.

Thank you for all the feedback. I think that when we originally made the Dual MC33926 carrier, we probably did not consider that way of using the INV pins, so we tied the two together to let the board be smaller. If we were to release a revision of that board, we would provide access to both INV pins. We have no current plans to make a new revision of that product, however, so a more immediate solution might be to use two of the single driver carriers.