I am new to bldc motor control and recently purchased the EVAL6235Q evaluation board. Instead of buying the suggested communication board I am attempting to control by directly manipulating the input pins. Can this be done?

[RGarc.646]

Specifically I am pulling the 'motor direction' pin high, setting voltage reference pins accordingly and then setting the 'enable pin' high. The motor runs but I have no control to as the speed. Can this be accomplished or can this board only work with the suggested communication board? Does this communication board send a PWM signal to accomplish the different speeds? Any and all help will be greatly appreciated. Thank you.

[Thomas L.]

Well according to the datasheet the speed is set by setting VREF to some voltage. The datasheet also gives an example on how to build a control loop around VREF and TACHO but I haven't really worked with this part yet.

[Cristiana SCARAMEL]

​You can refer to AN1625 where you can find more details on the L6235 operation and how to implements an analog speed loop, a fine tuning of parameters is necessary (refer to page 25 and following).

A better solution is to implement an external digital loop (PLL or FLL) and use the integrated PWM current controller for the current loop limit.