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Stepper motor driver

Discussion in 'Robotics & Mechatronics' started by Jabir, Mar 5, 2006.

  1. Dr-Chambers

    Dr-Chambers New Member

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    Just to confirm what stepper motor is this for?It looks like a unipolar one.
     
  2. persian_star

    persian_star New Member

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    Hello every1..
    This is my first post in this forum..I am so glad i have found u guys..

    I am Doing this project and trying to drive a Stepper Motor (Sanyo Denki ) which has DC 1.2 A , 1.8 DEG..

    Since its a group project, and i have decided to do the Stepper motor.. we will all connect our module to the I2C bus... and the micrcontroller im using is the P89LPC938.

    I just dont know how to start this project!...What driver to use, what I2C buffers to use and its all so bad :(

    Can some one please Tell me at least how to begin this project !! :(

    Thnx
     
  3. Ubergeek63

    Ubergeek63 Well-Known Member

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    the stepper chips generally use SPI or a two wire step/direction control system. Unless you *want* unnecessary complexity, get one of the 2A chips from Allegro. If you insist on using I2C get an I/O chip to drive one of them.

    Dan
     
  4. dave

    Dave New Member

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  5. persian_star

    persian_star New Member

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    Thnx

    Does anyone know what frequency the I2C needs to be intefracing? I want to add an external crystal for the interface of I2C and the microcontroller.. i jus dono wat frequency the I2c intefraces at..

    I have already read the data sheet for the I2C... Though there might be some1 here who knows it already..

    thnx
     
  6. blueroomelectronics

    blueroomelectronics Well-Known Member

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    I2C is usually 100kHz or 400kHz
     
  7. persian_star

    persian_star New Member

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    Thnx for ur reply.

    SO what would be the crystal value?!
     
  8. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Crystal for what?
     
  9. persian_star

    persian_star New Member

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    well as i said.. i want to place an external crystal and the value of that crystal needs to be the frequency at whch the I2c interfaces at.

    Is that clear?
     
  10. blueroomelectronics

    blueroomelectronics Well-Known Member

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    No. I2C is a communications bus that clocks data around. I2C can generally be run from DC to 100kHz for almost all I2C devices. It's an 8bit data stream with address / data. Google Philips & I2C.
     
  11. persian_star

    persian_star New Member

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    Yea well..

    I m using a microcontroller and a steper motor.. and am trying to run the steper motor using the driver and stuff..

    But the I2c is used as communication bus to send the data around ( to both PC and the other parts ), as this is a group project, every one is using this I2c bus and i need to know the speed at which this I2C is interfacing..!!

    :( i dono how else to explain it.
     
  12. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Last edited: Dec 18, 2008
  13. persian_star

    persian_star New Member

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    I have already had a look through that and the only thing it says is the clock frequency.. which is not wat im after..

    Thnx
     
  14. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Well if you read through it then you should understand I2C. Your MCU may or may not have I2C hardware built in. Easy if it's built in, else you simply have to toggle the bits out. Consider the 100kHz the maximum speed...
     
  15. 3v0

    3v0 Coop Build Coordinator Forum Supporter

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    In the most simple terms.

    The I2C master drives the SCL line high and low as needed to generate clock pulses. This alone determines the frequency of the data transfer.

    The I2C slave watches the SCL and SDA lines but does not expect any specific frequency. It just watches for bits as determined by SCL and SDA.

    Multi-master have a synchronization procedure but so long as you stay away from such setup you can ignore. it.
     
  16. persian_star

    persian_star New Member

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    Right ok..

    U know about the pull up resistors Rp from the SDA lines to the Power Supply, VDD, What are the common values of Rp Resistors?

    And do they only need to be placed from SDA lines or do they also need to be put on the SCL lines?
    thnx
     
  17. blueroomelectronics

    blueroomelectronics Well-Known Member

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    10K will work at normal speeds, else 4.7K

    You can place a 10K at the beginning and another at the end of the data lines. That works quite well.
     
    Last edited: Dec 18, 2008
  18. persian_star

    persian_star New Member

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    u mean placing 2 10K on the Data lines?

    I had a look at the data sheet and some of the websites.. most of them put the one of the Data line.. but not all put one on the S clock line.

    Thnx
     
  19. blueroomelectronics

    blueroomelectronics Well-Known Member

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    If it's a single master I2C then you can probably skip the 10K on the SCL line. I'd use them on both as resistors are really cheap.
     
  20. persian_star

    persian_star New Member

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    Thank you very much..
    u ve been a gr8 help..
    Thnx
     
  21. persian_star

    persian_star New Member

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    here is the schematic..

    If u could have a look at it quickly so that i can remove it, becauase ppl from my course might visit the same forum and copy it.. so cuz of the plagirizm thing i will take it off as soon as u guys inform me ..

    Thnx
     
    Last edited: Dec 18, 2008

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