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HPSW on DRV8825HW203 Always closed...

2021-07-20
2021-08-15
  • Juan Gonzalez

    Juan Gonzalez - 2021-07-20

    Hi. I have a DRV8825HW203 board working fine without HPSW. I have added the switch and changed the config file to account for it but then I have realized the program always read the switch is closed... I have cheched the switch itself and works fine but for some reason the program does not read it properly, I think. As a consequence when I move +500 steps, for example, it moves but the position resets to 0 inmediately, so I can never go back...
    Has anybody found this problem before?
    Cheers
    Juan

     
  • brownrb

    brownrb - 2021-07-30

    Hi
    Can you please let us know what firmware you are using, I am assuming you are using the Windows application to move the motor? What version.

    The HPSW needs a pullup resistor R5 (100K to 470K) to 5V in order to work. Did you fit this on the PCB

    The easy way to test is
    Start Arduino IDE
    Open up the serial port monitor
    set speed to 9600, no line feed
    in the top text line, type
    :50#
    and click send
    the response should be l1#
    The 1 indicates it is enabled in firmware - if 0 then hpsw is not enabled in firmware

    If the value is a 1 to the :50# call, then
    in the top text line, type
    :63#
    and click send
    the response should be H1#

    then close the switch,
    in the top text line, type
    :63#
    and click send
    the response should be H0#

     
  • Juan Gonzalez

    Juan Gonzalez - 2021-07-30

    Hi. Thanks for the extensive reply. I am not at home to test the commands to suggest, I'll do it in 15 days. The firmware I am using is 308. I bought the FIRBT PCB in January, and all I have done is putting a switch connected to the HPSW pins at the PCB...
    Cheers

     
  • brownrb

    brownrb - 2021-07-30

    Apologies for the long delay, you post was in a queue awaiting approval and I had not seen it till today.

    Cheers
    Robert

     
  • Juan Gonzalez

    Juan Gonzalez - 2021-08-12

    Hi Robert.
    I have done the test you suggested:
    1. The HPSW is enabled: I receive the l1# reply
    2. The pullup resistor is there: it is R9 in the PCB FIRBT rev3 model (I have checked the schematics). With a multimeter, I have measured 5V at the HPSW pins when the switch is open, and 0 when is closed, as expected BUT
    3. The :63# command always receive a H0# response, for both open and closed states.

    If I connect the windows app mini (2.3.5.9) and chech HPSW status always says OPEN, while according to your explanations H0# corresponds to closed... This is weird. In fact it is clear that the software is always detecting the closed state because if I move out a few steps the position is inmediately reset to 0... I have to disable HPSW in the firmware to work normaly with it...

    Any clues?
    Cheers again

     
  • brownrb

    brownrb - 2021-08-13

    Please update to the latest firmware 312 as there were a number of correctiopns to hpsw code since 308

    With a multimeter, I have measured 5V at the HPSW pins when the switch is open, and 0 when is closed, as expected
    CORRECT

    The :63# command always receive a H0# response, for both open and closed states.
    Hmmmm

    Is it a two pin switch or three pin switch. If 3p then wire NO and COM to header J14

    if the switch is closed it basically drives the input pin low. When the switch is open then the pin floats high from the resistor. Your tests confirm this

    myDriverBoard->get_hpsw() - then hpswstate reflects the state of the pin D12

    Please run attached program and let me know the results

    Cheers
    Robert

     
  • Juan Gonzalez

    Juan Gonzalez - 2021-08-15

    Hello Robert.
    I have finally found out the problem, thanks to your help . At the beginning the program always said "closed", but I have traced the problem and detected that there was a short at the connector. Some test were done without it, so the readings with the multimeter went fine, then with everything mounted it failed...
    Anyway, thanks a lot. I has been useful to better understand how the program works.
    All the best
    Juan

     

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