Part Number:DRV8308EVM
I recently purchased a DRV8308EVM, and I have successfully got it spinning in PWM mode, this works no problem. I have not been able to get it working at all in closed loop speed mode. I am using the EVM GUI software.
I have followed section 3.2 of the users manual - "3.2 Quick Guide to Spin With Speed Control" to the letter. I think that the GUI software is not working properly though, because pressing any of the buttons in the second tab does nothing at all, except for the buttons that are also in the first tab. To clarify:
-Changing the "control mode select" button does nothing - A PWM signal continues to come out of the MCU.
-Changing the CLK frequency dial does nothing - The frequency of the signal coming out of the MCU is always 25KHz, and I have never seen it be anything else
-Changing any of the gains etc in the side panel does nothing. I can change the SPDGAIN and LOOPGAIN to 0 and the motor continues spinning, so clearly something is wrong.
In addition to this, if I go to the third tab "all registers" and try changing the mode to closed loop (SPDMODE to 0 instead of 1) then the gui immediately switches the option back to "1 - PWM" This is frustrating as the GUI is not letting me change mode at all. I tried manually writing to this register using the box at the bottom of the GUI, and confirmed I had done so correctly by reading it back but there was still not change the motor only spins in PWM mode. I know it is in PWM mode because the RPM changes with both the supply voltage VM and the load I place on the motor.
At this point I am all out of ideas. Can you provide advice on how I can put the DRV8308 in closed loop speed mode? The main reason that I bought this product is because of the feature, so I cannot really use it in my product unless I can get it to work.