Hi. I see that the motor controller in question (product 3758) uses six GPIO pins (specifically, 5, 6, 12, 13, 24, and 25). I suspect several more are used for power transfer. I want to use direct wire connections between the controller and the Raspberry Pi instead of using the full 2x20 female header. Could you tell the minimal number of connections I’d need to make for the board to work properly? Thanks.
If you do not use the female header, you’ll also have to (With addition to the 6 connections you have mentioned above) connect 5V and GND pins of the controller with those of the Raspberry PI.
As shown in the schematic at the bottom of the Dual MAX14870 Motor Driver for Raspberry Pi product page, the 6 GPIO pins you mentioned, as well as a common ground are the only connections made to the Raspberry Pi by default. So, those are the only connections you need if you power both devices separately from one another.
Otherwise, if you want to power the Raspberry Pi from the motor driver board by adding an appropriately sized regulator to the motor driver board (as described in under the “Powering the Raspberry Pi from the motor driver board” heading on the driver’s product page), you will also need to connect the 5V output from the driver/regulator to one of the 5V pins on the Raspberry Pi header.