I am trying to control the speed of a dc motor with VNH5019 and Arduino using open loop controller just to see the open loop characteristics. I'm changing the pwm signal to vary the speed of the motor, but it does not. I changed the duty form 0 to 1 (arduino pwm reference from 0 to 255), even driver gets correct pwm signal from Arduino, motor driver output voltages has reached to max quickly and get saturated.
If I am correct it should show a linear variation of speed with pwm.
I have attached the experimental result with this. Can any one give me some suggestions to get it correct.