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DRV8834: TRIANGULAR WAVE

Prakhar Jain
Prodigy 90 points
Part Number: DRV8834
Other Parts Discussed in Thread: DRV8824, DRV8846, DRV8880, DRV8811, DRV8884

Dear Sir,

We are facing settling time issue with our stepper motor ( full step angle 1.8 degree). To resolve this we plan to give triangular wave i.e. acceleration and deceleration . How can I do it ? Can you point to any C code?

Thanks!

Prakhar

  • 0
    TI__Guru** 114905 points
    Hi Prakhar,

    Assuming you are using the STEP/DIR interface, you are decreasing the time between step inputs to accelerate and increasing the time between step inputs to decelerate.

    Try a search for stepper motor library acceleration. You will find examples there.
  • 0 in reply to Rick Duncan
    Prodigy 90 points

    Thanks Rick for the reply. Yes I am using DIR, STEP mode

    On your suggestions ,I did find several links example forum.arduino.cc/index.php

    I could not find any thing specific to DRV8834

    I wanted to know  do I need to use M0 and M1 pins also which for full stepping is ground or do I need to figure out PWM in full stepping mode? It will be really great if you could point to a direct link for DRV8834 since apart from triangular wave I need to test S curve too , to check reduce vibrations. I am relatively new to firmware development.

    Application: Motorized XY stage for medical device

    Thanks!

  • 0 in reply to Prakhar Jain
    TI__Guru** 114905 points
    Hi Prakhar,

    The STEP/DIR interface is similar across stepper motor controllers. This is no difference between the DRV8811/18, DRV8824/25, DRV8834, DRV8846, DRV8880, DRV8884/85/86 when using the STEP/DIR interface.


    Setting M0/M1 allows you to set the number of microsteps/step. Using more microsteps changes how the indexer (see Table 4 of the datasheet) is incremented or decremented.
    What step rate do you want to use?
    What decay mode do you want to use?
    What is your system voltage and what is the motor specification (R/L/I/V)?

    Because the current is regulated, voltages above the voltage rating of the motor can be used. This allows the motor speed to be increased.
  • 0 in reply to Rick Duncan
    Prodigy 90 points

    Dear Rick,

    Thank for patient and timely responses. I appreciate. I am just collating 

    Application: XY translation stage with a mounted camera. The stage has to move in precision and camera captures images(tiles) and finally constructs a 2D panaroma/mosaic . So we have to capture 10,000 tiles and then stitch them together. If between tiles there is a delay for stablilization then overall delay is an hour. Right now I am giving fixed delay of 2ms and M0 and M1 are ground ; current limit is set for 1A. 

    Issue: Settling time of stage is upto 300ms i.e. even if I rotate the motor with one full step of 1.8 degree still the stages takes its own time to settle down ; this is reflected in camera which gives running images .  I want to reduce this . I need your support in earnest.

    Queries:-

    1. Please suggest weather to use fast/slow/mixed decay to reduce the setting time?

    2. Weather to run the motor in DIR/STEP or Phase/enable mode to reduce the settling time between ?

    3. Is it advisable to use mechanical rotary dampers  ? Do these help ?

    4. I read that acceleration and deceleration pulses helps here. Is it correct ?

    5. What voltage and current should I drive the motor at ? I read one has to drive at higher voltage and keep the current fixed, how can I do that.

    6. Any other tricks with DRV I can use.

    7. For a proper H/W design which of the figure should I be flowing (there are several circuits mentioned in datasheet)?

    I am attaching the motor datasheet I am using. Currently I am using DRV8834 break out board from Polulu but will be making a custom H/W next week.

  • 0 in reply to Prakhar Jain
    Prodigy 90 points

    Attached is datsheet of stepper motorEVPS-17H-001.pdf