DRV8824: Step frequency can not reach 20K

Hello,

How fast are you trying to spin the motor, and with what microstepping level? I see in the schematic MODE0/1/2 all pulled up to 3.3V, so that should be 1/32 microstep.  

Often this occurs when your power supply voltage or current is not enough to spin the motor for the given load, or the motor is too small for the load.

Does it exhibit the same behavior with no load on the motor?  

Make sure your step signal follows the pulse duration set in 6.6 Timing Requirements, with a high and low time of at least 2.8us.  

Cheers,

Jacob

Hi Jacob,

    Customer use DRV8825 to replace 8824, is the same problem in step frequency is higher 10K.

    The load of motor can't be unload, they test the Output of A&B, Can you determine the cause according to the waveform.

    locked,

normal,

Yellow is A+, blue is STEP

Hello,

Are these current waveforms? They do not appear to be 1/32 uSteps. Please send us the current waveform of the motor phase either A or B when you run the motor at 1k PPS and 10k PPS. Do you happen to have the motor datasheet? Specifically with speed vs. torque plots at various supply voltages? Do you use an acceleration profile to ramp up the speed in the application? Load inertia often times will not allow a stepper motor to spin if spun from 0 to 10k PPS with load.

Regards, Murugavel

Hi,

   Motor specific

Hello,

Can you please give us a little more information so we can better assist you?  Such as the below info: 

• Do you use an acceleration profile to ramp up the speed in the application? Load inertia often times will not allow a stepper motor to spin if spun from 0 to 10k PPS with load.
• Do you happen to have the motor datasheet with speed and torque plots?
•  Please send us the current waveform of the motor phase either A or B when you run the motor at 1k PPS and 10k PPS.

Regards,

Jacob

Hi Jacob,

   Do you think customer need use more load ability like DRV8452,

  The have no condition to test current, they test A&B output voltage,

  Normal

 Locked

Motor screen,

The motor appears to be a 3 amp max NEMA 23 motor - 57HBP56AL4 (2A 1.2NM) (link2)

user5883945 said:

   Do you think customer need use more load ability like DRV8452,

That motor is large, but I think a DRV8825 should be able to drive it.  DRV8824 is probably too small to drive it reliably or quickly.  

A few questions:

1. Do you have any EVMs you can test with to make sure this works with the driver on our own EVM?  
2. Thank you for the screenshots, but can you post one with a smaller time scale, showing only 1 full cycle of the motor? 
3. What RISENSE value / voltages have you used? 
4. And please answer whether you have tried to spin the motor with an acceleration profile, slowly ramping up to the target 10K RPM.  

Regards,

Jacob

Hi Jacob,

1. Do you have any EVMs you can test with to make sure this works with the driver on our own EVM?  

// No EVM

2. Thank you for the screenshots, but can you post one with a smaller time scale, showing only 1 full cycle of the motor? 

   Will provide current test as attachment

3. What RISENSE value / voltages have you used? 

as attachment.

4. And please answer whether you have tried to spin the motor with an acceleration profile, slowly ramping up to the target 10K RPM. 

   Customer set some value before reach 10K.

test.docx

Thank you for the current waveforms!

Give me another day to review these with a more experienced coworker and I'll get back to you. 

Regards,

Jacob