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Maximum STEP frequency available on CPG004_DRV88xx EVM

Ralph Reinhold
Prodigy 80 points
Other Parts Discussed in Thread: DRV8825, MSP430F1612, DRV8824

The DRV8825 technical data sheet shows a maximum frequency 250 kHz, The CPG004 GUI instructions tell me that I can set the step frequency but nothing about the allowable maximum.  It appears that the software in slvc595/CPG004_RB_MSP430F1612_Firmware_LMD_TI gives me the capability to set it to anything up to 250 kHz. 

 Logically, there should be issues in realizing a stepping frequency a significant portion of the 35 kHz PWM frequency. I would like to ramp to 5 or 6 kHz. Where will the be a problem?  

Presumably, six or seven samples per phase is going to give me some noise. Is there anything else I need to look for?

  • 0
    TI__Guru** 114905 points
    Hi Ralph,

    The maximum step speed (PPS) of the DRV8824/DRV8825 is 65535. As you mentioned, the firmware can be changed, but I believe the variable is a sixteen bit variable.

    The speed of the stepper motor is dependent on the motor inductance and system voltage more than the DRV8825. Some motor manufacturers provide a curve of torque vs step speed at a specified voltage. Also included are starting speeds, and sometime acceleration rate.

    To achieve 5 or 6kHz may be possible, but an acceleration and deceleration ramp will most likely be required.
  • 0 in reply to Rick Duncan
    Prodigy 80 points

    Hi Rick

    Thanks for the prompt reply. I was out of the office when it came in and read it. It was just what I was looking for. When I got here and could open the site, it asked me to use the verify button and I never could find it.