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DRV8711: Unattended stop without fault sygnal

Pavlin Stoyanoff
Expert 1715 points
Part Number: DRV8711


Greetings! I am using your DRV8711 to control NEMA 23 stepper motor. Here is my schematic -> [url=https://drive.google.com/file/d/1rcTDDpATe-NKQgcMUN_ZAlIfxM6Nyr-C/view?usp=sharing]Click[/url]

I`ve supplied the driver with 12V and I am controlling SLEEP, RESET and DIR pins through 74LS373 octal buffer. I have respective pull up or pull down resistor 2.2k. Here are my settings->

#define CTRLRegisterValue 0x0C11//4 steps

#define TORQUERegisterValue2A 0x11CD//205 torque 2.00A
#define TOFFRegisterValue 0x20C8//100us
#define TBLANKRegisterValue 0x3000
#define DECAYRegisterValue 0x4580
#define DRIVERegisterValue 0x65F6
#define STATUSRegisterValue 0xF000

So here is the problem. I have 4 drives connected with ribbon cable to the main PCB. Sometimes on power up some of the motors don`t start. I have written the correct values the registers. I confirm it after every write, but the motor is not in a break mode(the shaft rotates freely), doesn`t move and there isn`t a fault sygnal. I`ve added some RC filters to the SLEEP, RESET, DIR and STEP inputs and it`s better. But it still happens. Any suggestions what can cause that?

Thanks!

  • 0
    TI__Guru 56650 points

    Pavlin,

    Change to another word, you want to know which signal holds the motor off after power up.

    Would you measure each DRV8711's SLEEP and RESET pin voltage to see which one is different than others?

  • 0 in reply to Wang5577
    Expert 1715 points

    I`ve measured them all -> the values were equal to 3.22V for high level and 2.2mV-4mV for low level. So increased the supply voltage to 3.44V but I don`t think there is a change. Do I need to go higher? My uC is operating on 3.3V with absolute max 4V. There are minor losses on the lines, the voltages on the Reset and Sleep pins are similar to the power supply.

    In reset I am setting both Sleep and Reset high to reset the driver. After 200ms I set Sleep high and reset low. After extra 100ms I am starting to setup the registers. I don`t think my power up procedure is wrong. And there is more, it did this trick while working. It happened only once so am not sure if it is isolated case. Usually it does it on power up. 

    Any other ideas?

    Thanks!

  • 0 in reply to Pavlin Stoyanoff
    TI__Guru 56650 points

    Pavlin,

    I cannot open the file with the schematic link. Please upload the schematic to here.

    "And there is more, it did this trick while working. It happened only once so am not sure if it is isolated case. Usually it does it on power up."

    "it did this trick while working" what does this mean?

    "It happened only once so am not sure if it is isolated case. Usually it does it on power up." When the abnormal case happens, would you measure VCP pin voltage also?

     

  • 0 in reply to Wang5577
    TI__Guru 56650 points

    Pavlin,

    Hope you have fixed the issue. Please let me know if you have some updates.