DRV8462EVM: STEP count fail

Higa-san,

We are investigating this.

Regards,

Ryan

Higa-san,

Few points of clarification here.  

As seen in the motor, is the position similar every time you issue 195 steps?  Meaning, does the motor move to the same amount every time.  

The timing in this mode may not be perfect as only the rising edge of the STEP signal is what triggers the DRV8462 to take a step.  So, I am wondering if the actual number of rising edge pulses generated is different OR just the timing is different.  

It would be much easier to test with a smaller number of steps like 5 or 10 and count the number of rising edges.

Regards,

Ryan

Hi Ryan-san

Thank you for your reply.

The amount of rotation of the motor was changing.
Sometimes the amount of change was small, and sometimes it increased significantly, and it was not constant.
Also, increasing the number of steps seems to increase the frequency of outputting the wrong number of steps.
For my clients, a setting of 195 steps is mandatory for evaluation.
Could you actually check it with EVM?

Best regards,

Higa

Higa-san,

Ok, that makes sense.  I will check with EVM.  

If it is an issue, I don't believe it is with the device.  Either a firmware or GUI issue that we will need to address.  

If your client has their own software, they can drive EVM with their MCU and preform the desired step count.

Regards,

Ryan

Hi Ryan-san

I also agree with your opinion.
If you can identify the cause, it would be very helpful if you could fix it.

Best regards,

Higa

Higa-san,

I have assigned this to Akshay who is working on confirming this behavior and the root cause so we can address it in firmware/GUI.

Please give us some more time.

Regards,

Ryan

Hi Ryan-san Akshay-san

Do you have any update?

Best regards,

Higa

Higa-san,

Not yet.  I will check with Akshay.  

Regards,

Ryan

Hey Higa-san,

I have tried to replicate your situation on our EVM and I am also noticing wrong number of steps being output. 

I also noticed that the higher step amounts led to more wrong steps. 

Are you always getting more steps than being set in the GUI or are you sometimes getting less steps?

We are going to investigate this further. I noticed that the acceleration setting seems to have some sort of relation to the frequency of getting wrong number of steps and needs to be investigated further.

Best,

Akshay

Higa-san,

I plan to keep this post open until we get a final conclusion on this.  The apps engineer responsible for this part is out of office until 02/13.  So, it will take some time to resolve this fully.  Please wait until then to post for follow-up.

Regards,

Ryan

Hi Akshay-san

Thank you for your confirmation.

>Are you always getting more steps than being set in the GUI or are you sometimes getting less steps?

I always got more steps than being set in the GUI.

Best regards,

Higa 

Hey Higa-san,

Thank you for the additional information. We will take note of this.

Best,
Akshay

Hi akshay-san

Do you have any update?

After that, I found some things that I think are probably bugs.

 1.“Current Steps for Learn”
Mismatch between window settings and register reserved values

2.Trque DAC Setting

Some intermediate setting values are not displayed and register settings cannot be made.

Best regards,

Higa

Hey Higa-san,

Not yet. I will check in with our apps engineer responsible.

Thanks for the additional information.

Best,

Akshay

Hi Higa-san,

I'm back in office and reviewing the firmware for the STEP count issue. I have not identified the firmware bug yet. I'll keep you posted. Meanwhile it would be better we have a separate thread for the new issues you mentioned. Could you also give specific examples for issues #1 and #2? Thanks.

Regards, Murugavel

Hi Murugavel-san

OK.

I will make a new post.

Best regards,

Higa 

Thank you, Higa-san.

Best,

Akshay

Hi Higa-san,

I assume the customer is using the desktop installation of the GUI version 0.1.0. This can be verified using the Help > About menu. See below.

I have found the firmware issue and have a fix to resolve this problem. I have attached the fixed firmware file in this post. Please use the following steps to replace the existing firmware with the new firmware for the desktop application. First unzip the attachment, you'll have a DRV84x2_DRV82x2_DRV89x2_EVM.out file. Close the desktop GUI app. Assuming the customer is using Windows 10 and used the default folder settings for installation navigate to "C:\Users\xxxxxxxx\guicomposer\runtime\gcruntime.v11\DRV84x2_DRV82x2_DRV89x2-EVM-GUI\target" folder. This folder will have an existing firmware file with the same name. Either delete or rename this file or move it to a different folder. Copy the new .out file to this folder. Now start the GUI app with the EVM connected and powered up. 

From the GUI Home page use the File > Program Device menu option. This will initiate an EVM firmware update. Note the firmware version will be unchanged. Programming will be indicated by the flashing red LED close to the USB port. After the programming is completed close the pop-up window. Click on the device tile and connect to the EVM. Try the "Step" control mode. Now the motor should move the desired number of steps correctly. Let me know if any questions.

DRV84x2_DRV82x2_DRV89x2_EVM.zip

Regards, Murugavel

Hi Murugavel-san

Thank you for your  support.

I have a question.

I think the latest version for GUI is 1.0.0(DRV84xx_DRV82x2_DRV89x2_EVM), is this incorrect?

Best regards,

Higa

Hi Higa-san,

The current EVM has pre-production silicon. For this silicon we recommend customer use v0.1.0 GUI. Do not upgrade to v1.0.0 GUI unless you change the driver IC on the EVM. Please refer EVM UG https://www.ti.com/lit/pdf/slou558. Please let us know if you or customer was able to use the firmware I sent for the v0.1.0 GUI and verify the STEP Control mode to work correctly. Thanks.

Regards, Murugavel

Hi Murugavel-san

I understood, but I have an additional question.

My customer plans to replace it with a production IC.
Is there STEP pulse issue with the latest Ver1.0.0?

Regards,

Higa

Hi Higa-san,

I have released a new version of the GUI for the production silicon, link for cloud version https://dev.ti.com/gallery/view/MotorDriversBSM/DRV84xx_DRV82x2_DRV89x2-EVM-GUI/ver/1.0.1/ and the link for the desktop windows app installer https://dev.ti.com/gallery/dl/MotorDriversBSM/DRV84xx_DRV82x2_DRV89x2-EVM-GUI/ver/1.0.1?platform=win. This comes with a new firmware version 0.25. When the GUI is connected to the EVM and clicked to the motor control page the GUI will popup a message saying a new firmware is available for updating the EVM. This information will be updated on the web this week.

Regards, Murugavel   .