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Checking EBB motor voltage from Inkscape



  • Ragnar,

    OK, I've been plotting now from Inkscape with 2.2.5 for about an hour, and I've reproduced the 

    EBB Serial Timeout.
    Plot paused by button press after segment number 4580.
    Use the "resume" feature to continue.

    issue. I'm also seeing the problem with the motor voltage.

    So, another thing- your suggestion about putting the pen servo in a more 'up' position upon reset. The problem here is that the EBB has no storage that survives reboots. So when you reset the board, it looses it's previous idea of where 'up' and 'down' where. And different folks may have their up and down settings in difference places, so I can't really pick a 'standard' position and have it work all the time. Thus the current 'middle' setting. I'd love to hear any ideas that could help solve this problem.


  • edited April 2014

    I can live with the servo in center at reset - my 'solution' is just to move the servo horn so this becomes the 'default pen up' position.

    I'am sort of glad you got the timeout as well, I was about to suggest that this 'bug' would not become apparent unless you were 'power-plotting' - like I am doing - for hours.

    For the resume option to work it would be nice to have the option to write the EBB commands to a file as well - by analyzing the file might be possible to figure out why it fails.

    Another option that would be nice is to have the EBB 'store' the 'home' position before starting the plot by setting the x and y count to zero.  By adding and subtracting the steps for egg and pen respectively as it goes along it would then be possible to return 'home' by a command. As it is now the inkscape extension 'assumes' that the last command sent is executed by the EBB and it's resuming to the following step, but if the EBB is paused 'mid-command' some steps will be lost.

    Happy Coding!

  • Ragmar - implementing the 'homing' would not be impossible, I think. It would be very easy for the EBB to keep track of the absolute step value for each axis. We could then have a 'go home' command, and a 'zero' (i.e. this is home) command. It would probably also be good to have a command that could retrieve the current global x and y step positions.

    To take advantage of it, somebody would have to make changes to the Inkscape extension. I haven't learned enough Python to do this.

    I actually do log all of the data to a file - sort of. I use a program called hub4hub that allows me to 'split' the serial port data inside Windows and monitor (and record) every byte that goes between Inkscape and EggBot. I can also send commands to EggBot while Inkscape is still running and connected to it, which is really cool. But the point is that I can clearly see why Inkscape is thinking that the pause button got pushed. The serial data coming back from the EBB is getting jumbled. And so when Inkscape sends the QB command (Query Button), the response should come back "0\n\rOK\n\r". But instead it comes back "OK\n\r0\n\r" for some reason, and this messes up Inkscape. I'm looking into that right now.

    I have fixed the problem with 2.2.4 where the motor voltage reading is broken. I had left in some debugging code and it messed with pin RC5 (the analog input we measure the motor voltage on). The next version will have that fixed.

  • Hi.

    Making changes to the eggbot extension to take advantage of a home command might be within my capabilities - worth giving it a try - the difficult part for me is to wrap my head around the OOP (Object Oriented Programming) part ;-)

    Where did you find the hub4hub serial splitter? I have used Eterlogic virtual port software to do this - unfortunately the 64bit version has to be bought, the 32bit version is free but will not install on a 64bit OS - the price for the 64 bit version is very reasonable - might go ahead and buy it.

    Interesting how the QB command return got 'jumbled' - I am curious what is causing this just 'every now and then'. Nevertheless - I am impressed by you coding!

  • Ragnar, hub4com is part of com0com project, which is _very_ cool and we use it often at my day job. I'm running it on 64 bit Windows 8.1. Free and open source.

    I'll let you know what's going on as soon as I can squash this bug. I got pulled away from this for another couple projects that needed work tonight. So it will need to be tomorrow night.

  • edited May 2014
    Hi Brian.

    I have moved the servo horn on the servo in order to lift the pen a few mm off the egg when in the reset (middle) position. I ended up on having pen up / pen down values of 24 and 19 respectively in Inkscape. When resetting the EBB the servo does a quick 'pen down' movement before going to the middle position causing the pen to 'peck' the egg. Any possible solution for having the servo go straight to middle position?
    Would it be a good idea to incorporate the 'new' servo horn setting in the Eggbot assembly guide?
    (I once suggested pre-setting the potmeter to middle position on the EBB board to avoid some of the beginners problems using the eggbot but generated no interest whatsoever from EMS ;-)  )

    Installed the com0com software, works like a charm. What are you using as a terminal after MS removed Hyperterminal from windows?

  • edited June 2014

    Hi Brian. Any chance of getting an updated version anytime soon?
    Would really like to have a working solution (from Inkscape) incorporating the 'long moves'.

    Quote (April 30th ;-) );
    I'll let you know what's going on as soon as I can squash this bug.
    I got pulled away from this for another couple projects that needed
    work tonight. So it will need to be tomorrow night.

  • EmbeddedMan

    Would it be worth trying software to emulate com ports such as this

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