I'm assuming you have not designed the controller yet. To design a PD controller you can use the PIDTune function. It needs to be discretized using ToDiscreteTimeModel to get the equations that can be be used to program the Arduino.

Frank, A PID controller should have three gain constants ("P","I", and "D"). You can turn a PID controller into a PD controller by simply setting the integral gain "I" to zero. If you have found example of code for PID controllers that fit your configuration, you should try that. Then the difficult part of the problem becomes determining the values for the proportional "P" and derivative "D" gains. That is where the PIDTune and ToDiscreteTimeModel functions in the Wolfram Language can help. They do require that you have at least a rough approximation of a mathematical model for your system. Alternatively, there are purely experimental techniques for tuning PID gains, but those are outside of the scope of the this community.

thank you for your time & efforts but unfortunately those links were just too meaningless for my understanding/comprehension level, its just to symbolic and or vague, maybe something english will suffice? or even better in C++ / Arduino programming language will be best, i have gone thru many youtube videos dozens and just not clicking in again either they speak to vague or the application example is non related to my application, im dealing with a dc motor and a potentiometer for feedback close loop and what i need is the PD Controller and often you everything is about PID or PI