Welcome to Our Community

Some features disabled for guests. Register Today.

PWM ISSUE BLACK BOX

Discussion in 'General Talk' started by Nicholas Emord, Jun 3, 2020.

  1. Nicholas Emord

    Builder

    Joined:
    Dec 17, 2018
    Messages:
    7
    Likes Received:
    1
    Greetings,

    I'm experiencing an issue with the PWM for the tool head. I hooked up and O-Scope and i'm not getting any pulses. On top of this when M3 command is run to turn on tool head voltage only jumps from 0- 400mV. Any suggestions?
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    7,835
    Likes Received:
    2,606
    Are you sending M3 on its own (incorrect), or M3 Sxxxx where xxxx is a number between 0 and 1000 (with default grbl settings) or between the values set in gnea/grbl and gnea/grbl if you've modified those
    Also, not sure what you are connecting, but if its a Laser, read gnea/grbl (Laser mode only turns on laser/pwm during a G1/2/3 move)

    With PWM enabled you need the S-Word to tell Grbl how much PWM to dial up
     
  3. Nicholas Emord

    Builder

    Joined:
    Dec 17, 2018
    Messages:
    7
    Likes Received:
    1
    Thanks for the quick reply. Yes, I have used M3 by itself and M3 Sxxxx M4 Sxxxx to try to generate a signal. Perhaps the board is broken?

    For context I'm trying to use this signal to integrate a 3D imaging system and all I need is a set frequency from PWM and a high signal from either the analog on, Dir on, or the Relay.

    Best,
    Nico
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    7,835
    Likes Received:
    2,606
    So just a note, but the S-word sets the Duty cycle, you can't vary the PWM frequency in realtime (you can set a few different frequencies with the prescalers at compile time)

    - paste your Grbl settings (Serial console > Send "$$" > copy paste the output)
    Any events you know about that would make that likely? (miswiring at some point, etc) - as they do go through a QA prior to shipping, so its unlikely unless you have any history to make that more likely
     
  5. Nicholas Emord

    Builder

    Joined:
    Dec 17, 2018
    Messages:
    7
    Likes Received:
    1
    Thanks for clarifying, I figured via the O-scope it was hard set to 1000Hz +/-2%
    No cant think of anything that would have caused it. I'm pretty handy when it comes to not breaking expensive stuff at work so far.

    [17:10:36] [ $$ ] $0=10 ;Step pulse time, microseconds

    [17:10:36] [ $$ ] $1=255 ;Step idle delay, milliseconds

    [17:10:36] [ $$ ] $2=0 ;Step pulse invert, mask

    [17:10:36] [ $$ ] $3=1 ;Step direction invert, mask

    [17:10:36] [ $$ ] $4=1 ;Invert step enable pin, boolean

    [17:10:36] [ $$ ] $5=0 ;Invert limit pins, boolean

    [17:10:36] [ $$ ] $6=0 ;Invert probe pin, boolean

    [17:10:36] [ $$ ] $10=1 ;Status report options, mask

    [17:10:36] [ $$ ] $11=1.000 ;Junction deviation, millimeters

    [17:10:36] [ $$ ] $12=0.002 ;Arc tolerance, millimeters

    [17:10:36] [ $$ ] $13=0 ;Report in inches, boolean

    [17:10:36] [ $$ ] $20=0 ;Soft limits enable, boolean

    [17:10:36] [ $$ ] $21=1 ;Hard limits enable, boolean

    [17:10:36] [ $$ ] $22=1 ;Homing cycle enable, boolean

    [17:10:36] [ $$ ] $23=3 ;Homing direction invert, mask

    [17:10:36] [ $$ ] $24=300.000 ;Homing locate feed rate, mm/min

    [17:10:36] [ $$ ] $25=300.000 ;Homing search seek rate, mm/min

    [17:10:36] [ $$ ] $26=10 ;Homing switch debounce delay, milliseconds

    [17:10:36] [ $$ ] $27=10.000 ;Homing switch pull-off distance, millimeters

    [17:10:36] [ $$ ] $30=1000 ;Maximum spindle speed, RPM

    [17:10:36] [ $$ ] $31=0 ;Minimum spindle speed, RPM

    [17:10:36] [ $$ ] $32=0 ;Laser-mode enable, boolean

    [17:10:36] [ $$ ] $100=200.000 ;X-axis steps per millimeter

    [17:10:36] [ $$ ] $101=200.000 ;Y-axis steps per millimeter

    [17:10:36] [ $$ ] $102=200.000 ;Z-axis steps per millimeter

    [17:10:36] [ $$ ] $110=7000.000 ;X-axis maximum rate, mm/min

    [17:10:36] [ $$ ] $111=7000.000 ;Y-axis maximum rate, mm/min

    [17:10:36] [ $$ ] $112=7000.000 ;Z-axis maximum rate, mm/min

    [17:10:36] [ $$ ] $120=300.000 ;X-axis acceleration, mm/sec^2

    [17:10:36] [ $$ ] $121=300.000 ;Y-axis acceleration, mm/sec^2

    [17:10:36] [ $$ ] $122=300.000 ;Z-axis acceleration, mm/sec^2

    [17:10:36] [ $$ ] $130=340.000 ;X-axis maximum travel, millimeters

    [17:10:36] [ $$ ] $131=500.000 ;Y-axis maximum travel, millimeters

    [17:10:36] [ $$ ] $132=100000.000 ;Z-axis maximum travel, millimeters

    [17:10:36] [ $$ ] ok
     
  6. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    7,835
    Likes Received:
    2,606
    Looks alright...

    Can you do an M3 S1000 please
    Then screenshot window on both the serial console tab, and also the troubleshooting tab please.
     
  7. Nicholas Emord

    Builder

    Joined:
    Dec 17, 2018
    Messages:
    7
    Likes Received:
    1
  8. Nicholas Emord

    Builder

    Joined:
    Dec 17, 2018
    Messages:
    7
    Likes Received:
    1
    When I do this PWM Voltage jumps from 0 to 460mV with no Square waves
     
  9. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    7,835
    Likes Received:
    2,606
    - which GND are you referencing off on the scope (which gnd on BlackBox)
    -100% sure scope scale is correct. 470mv sounds awefully close to a /10 division of +-5v expected output
    - have you reflashed Grbl with any other versions (for example 2 axes + servo or some 3rd party one)
     
  10. Nicholas Emord

    Builder

    Joined:
    Dec 17, 2018
    Messages:
    7
    Likes Received:
    1
    Hi Peter,

    So I went through and factory reset and calibration on my Scope. Looks like you were on to something because the function generator I was using to do a sanity check was giving me 1.5V when it should have been 15V. After calibration I'm now reading 5V pulses from the output of the PWM. Crazy. Thanks for your help.

    Best,
     
    Peter Van Der Walt likes this.
  11. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
    Staff Member Moderator Project Maker Builder Resident Builder

    Joined:
    Mar 1, 2017
    Messages:
    7,835
    Likes Received:
    2,606
    Glad you got it sorted, yeah suspected an instrumentation fault because thats very unlikely to be Grbl doing that (;
     
    Nicholas Emord likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice