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DRV8886EVM: How to Adapt This EVM for Different Interface Application

Lin Li
Prodigy 180 points
Part Number: DRV8886EVM
Other Parts Discussed in Thread: DRV8886, DRV8880, LM317

Hi ,

I am trying to adapt this DRV8886EVM  for stepper motor application  with such interface as below,  

36V for VM.  

5V signal on/off for enable /disable  of motor rotating.

5V signal  on/off  for direction,(forward /backward)

once our position  setting is achieved then just disable stepper motor  motion with enable/disable signal off,  if any difference has , internal logic  control circuitry compare setting position value with rear position value and decide to provide the corresponding enable and direction signal.  

while current DRV8886 EVM interface  with outside is GUI operation.

consider one solution , feel still has difficult for my point of view.

using the original  DRV8886EVM included , FT232RL  inner 3.3V  regulator  provide power for  MCU  for optimized step signal ,  and then  using  electrical signal only to automatically control this DRV8886 EVM,,

but without  need the manual function in the GUI to use  wake/enable/direction slide button,I wonder whether there is  certain  device  can transfer this signal to GUI matching control input automatically  ?

like:           5V  interface enable signal   on  match to turning on(getting green ) wake and enable control input inside the GUI;   also turning on (getting green )  at start/stop steps  button  for the continuous mode inside GUI. 

                  5V  interface  direction signal  on match to direction (getting green) control input inside the GUI.

if this approach is not possible, I also  think to choose another TPS62122EVM  for substitution of FT232RL , but  the  interface control signal  is still 5V .need convert to 3.3V for signal to extra spare I/O for MCU  inside this DRV8886EVM. , I have to redesign a  adapted board combination TPS62122EVM and DRV886 EVM  main components with more optoisolator  for MCU input  signal  for enable and direction  interface signal , but the cost and work is much more . 

Regards

Lin 

  • 0
    TI__Guru** 114905 points

    Hi Lin,

    I am not sure I understand exactly what you are trying to do. Can you provide a basic block diagram?

    FYI --The DRV8886 can be separated from the mcu and driven by signals connected to header J4. This would allow you to control the DRV8886 using another mcu if desired.

  • 0 in reply to Rick Duncan
    Prodigy 180 points

    Hi Rick,

    I provide a basic block schematics for your reference in attachment.

    This compare the original design for DRV8886EVM   with  my proposal way because of this interface request.

    I also know this DRV8886 can be separated thus  may connect another MCU through  header J4, but  with either proposal  there is a  waste for current MCU  or   3.3 V regulator inside this DRV EVM.

    So I ask for whether may have a better solution based on this EVM .

    Regards

    Lin DRV8886 Project.xlsx 

  • 0 in reply to Lin Li
    TI__Guru** 114905 points

    Hi Lin,

    Thank you for the block diagram.

    The DRV8886EVM was intended to:

    1) demonstrate the capabilities of the DRV8886 using the GUI
    2) allow external control of the DRV8886 by disconnecting the mcu on the EVM and providing external signals.

    The firmware in the mcu is written to respond to the GUI commands.

    Connecting as you proposed will probably create many unexpected issues and delays.

    Have you considered looking for some type of carrier or breakout board? A quick web search found a DRV8880 breakout board. The DRV8880 does not have the internal current regulation.

  • 0 in reply to Rick Duncan
    Prodigy 180 points

    Hi Rick,

    Thanks for your kindly reminder for the breakout board  for the DRV8880, which also may provide the LDO 3.3V regulator inside for potentially power the CPU  possible.

    But consider the overall cost  and performance  for my prototype board and limited experience and efficiency  ,I may choose below combination as a solution:

    1  LM317 adjustable voltage regulator as power for MCU of DRV8886EVM,

    2  two optoisolator terminal for enable/direction  signal ( 5V input side , 3.3v output side  to transfer  signal to IO of MCU of DRV8886EVM).

    3  Use the orignal JTAG interface for removing the original firmware program  of MCU of DRV8886EVM.

    4    Programming  new   simpler program for fixed  continuous motion mode like 1/16 microstep , 75% full scale etc once enable signal trigger step .

    5   test mostly based on  DRV8886 EVM hardware    . no more MCU involved .

    6   finally combine all above into one single PCB.    

    I want to try above .

    Regards

    Lin

  • 0 in reply to Lin Li
    TI__Guru** 114905 points

    Hi Lin,

    This sounds like a good plan.