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Stall Detection in A3697 — Parallax Forums

Stall Detection in A3697

shoaibidreeschshoaibidreesch Posts: 1
edited 2012-07-30 07:21 in General Discussion
I am using A3967 chip for driving stepper motor of 1.8 degree.
Is there any way that, when stepper motor stalls at the end of the operation or during the operation, the A3967 just shut off the output automatically.
????

Comments

  • stamptrolstamptrol Posts: 1,731
    edited 2012-07-30 05:52
    Welcome to the forums.

    Steppers are used when it is acceptable to assume that a certain number of pulses will get the motor to where its supposed to be.

    In order to confirm that the motor actually got to where it was supposed to get, you will need some position feedback. That usually is an encoder, either buit into the motor or attached to the equipment being moved. The controller issues a command to move then watches the encoder to make sure the action was successfully completed.

    A servo system (not usual hobby servo) has continuous position feedback at all times but is a more expensive option.

    Cheers,
  • LeonLeon Posts: 7,620
    edited 2012-07-30 05:57
    There are stall detection techniques for stepper motors, such as monitoring the current, or the back-EMF.
  • idbruceidbruce Posts: 6,197
    edited 2012-07-30 06:07
    At first glance, the A3967 does not seem to offer that feature, however the use of an encoder would help you detect stall conditions. With the use of an encoder, the program would have to constantly monitor for lack of movement when movement should exist. If movement does not exist, then the output should be stopped.
  • idbruceidbruce Posts: 6,197
    edited 2012-07-30 06:09
    The A4979 offers stall detect: http://www.allegromicro.com/en/Products/Motor-Driver-And-Interface-ICs/Bipolar-Stepper-Motor-Drivers/A4979.aspx
  • idbruceidbruce Posts: 6,197
    edited 2012-07-30 06:15
    Additionally, I believe that part number should be A3967, instead of A3697. You may want to change the title if this is the case.
  • stamptrolstamptrol Posts: 1,731
    edited 2012-07-30 07:21
    And, as noted in the datasheet for the A4979, there are some limitations in the ability for the chip to detect a stall. The recommended solution is to monitor the motor with an external microprocessor.

    Cheers,
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