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DRV8711 eval: no function at all

Other Parts Discussed in Thread: DRV8711, DRV8711EVM, BOOST-DRV8711

I purchased a DRV8711 EVM to so if the DRV8711 is a possible replacement for the A4988. I had some trouble with the first board like the FAULTn LED not being lit as mentioned in another thread. Apart from that, I can not even activate the output stage. I did some measurements and found V5 not beeing present. According to the datasheet this is the 5V output from the DRV8711, so this voltage should be present even when the device is in sleep mode?!

The only function I see is the blinking status LED. I'm also not sure if communication between PC, microcontroller and DRV8711 is working as expected. Is there any way to check that? E.g. a simple SPI read to a certain register? Should the blink frequency of the status LED change during a transfer?

I already returned one board with V5 not beeing present and purchased a new one, but the problems still exist with the new board. J1 was missing on both boards, but adding a jumper to "JTAG" position doesn't make a difference.

Power supply is 24V= from a smal lab supply. Operation system is Win7 (32bit!).

With kind regards,

Thorsten Ostermann

  • Hi Thorsten,

    The DRV8711EVM initially powers up with nSLEEP driven to a logic low by the MSP430. When VM is applied, the V5 supply is inactive due to nSLEEP.

    Once the GUI is connected and the nSLEEP button is set to green, the MSP430 will drive to a logic high. This will enable the V5 to an active state and 5V can be observed on the V5 test point.

    The datasheet is unclear in this area, and will be updated. Thank you for pointing this confusion out.

    The easiest method to determine that everything is working properly is to set the nSLEEP to  "green". This will indicate that the PC, microcontroller and DRV8711 is communicating without the SPI. To confirm SPI communication, use the ENBL bit in the control register. It is checked by default, so a write to the control register will enable the AOUTx and BOUTx outputs. If no motor is connected one of the AOUTx pair will be high (at VM) and the other will be low. The BOUTx pair will also be enabled at this time.

    The JP1 jumper does not make any difference in operation. It is used when re-programming the micro.

  • Hi Rick,

    I assumed that V5 would be switched off when the device is in sleep, but I didn't realised that this signal is switched by the MCU. Shame on me ;) So I need to check the communication. The nSleep button gets green in the GUI, but the device remains switched off.

    For my application I planned to use V5 to supply my MCU and therefor tie nSleep to +5V, But according to your statement this wouldn't work? How can V5 be used for an MCU when you need +5V to activate the device?

    Regards,

    Thorsten Ostermann

  • Hi Thorsten,

    I am assuming you have the DRV8711EVM user guide. If not, it can be found at the DRV8711 product page. Scroll down to User's guide.

    There are two additional items required for V5 to power up. VM must be powered, which I am assuming it is.

    Also, the com port must have communication established. This could be where the problem is. If the incorrect port is connected, the GUI appears to communicate but does not.

    Check the device manager as you connect the EVM to the PC. Look under Ports (COM & LPT) for "USB Serial Port (COMx)" appearing and disappearing as you connect and disconnect.

    Next, select the COMx port in the previous step in the pulldown menu at the top of the GUI.  Then select "Connect" to the left of the pulldown menu. At this point, you should have communication.

    Note: An alternative approach without using the device manager exists.
    1) Open the GUI without the EVM connected to the PC
    2) Select the down arrow on the toolbar like area and note the COM ports available
    3) Connect the EVM to the PC using the USB connection
    4) Select "Refresh Com Port"
    5) Repeat step 2 noting the new COM port.  Select the new COMx port
    6) Select Connect to the left of the COM port pulldown
    Communications should now be established

    Let me know if this allows communication.

    Using the 5V regulator can still be done, but requires additional circuitry. A switch is required to set nSLEEP to a logic high. This switch uses VM clamped to <5.5V. Once the switch is activated, nSLEEP will transition to a logic high. This activates the V5 regulator powering up the MCU. Now the MCU can drive nSLEEP to a logic high, and keep V5 alive. If desired, the MCU can release nSLEEP and place the DRV8711 and the MCU in a power down mode until the switch is pressed again. This is a simple description of the circuit. The circuit may require some additional components such as debouncing of the switch and a diode to prevent the MCU output seeing the voltage from the switch before the MCU powers up.

  • Hi Rick,


    it seems that I used the wrong COM port. We have different USB2serial devices on that development machine. :(

    It would be nice to have some kind of feedback to see if the application established communication to the MCU. This would help to avoid these stupid errors.

    Thanks a lot,

    Thorsten Ostermann

  • Hi Thorsten,

    I am glad to hear it is working.

    Also, thanks for the feedback. I am not sure anything changes will be made on this GUI, but we will incorporate user feedback to improve future GUIs.

  • BOOST-DRV8711_GUIv1.0.exe not opening in my system, what can be the problem?
    system is Win7 64bit
  • Hi Vipin,

    Can you provide some more information?

    Is this the first time you have tried to open the GUI?
    Did you follow the instructions in the User's Guide?
    What do you mean "not opening"? Does any image or message appear? If so, can you provide the image?
  • yes, i didnt read the manual
    now I download the GUI Composer Runtime and try

    Thanks for the support
  • It's not good style to enter someone elses thread to open new questions. I was wondering why I got several email notifications from this forum. Now I see that you posted your request into my old question which was solved long time ago. Please stop this.

    Best regards
    Thorsten Ostermann
  • Sorry Thorsten Ostermann

    I was intended not to waste the space in TI forum by opening a new thread