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Adjusting BaudRate on Xpro V3

Discussion in 'Interfaces' started by Chris Robertson, Nov 14, 2019.

  1. Chris Robertson

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    Hi,

    We have been trying to use an Xpro V3 with a WorkBee CNC with our own custom modifications to utilise a handheld plasma cutter.

    However... Triggering the cutter causes a High Frequncy Pulse that radiates out and seems to knock out the USB connection to the Xpro. This was tried with a Raspberry Pi (Moderate success) and a laptop (Very fussy). After doing a lot of earthing the problem is still occuring.

    Anyway, I came up with the idea of using a TOSLINK cable to provide an alternative interfacing method, after some initial testing with a DIY FTDI and sending UART Data down the TOSLINK on a loopback I can Tx/Rx data, though after increasing the BaudRate to 115200 the data starts to corrupt. Frankly I think this is something I can work through by using the correct Capacitor values and Inverting the signal more efficiently.

    Anyway, my basic question is... can I reduce the Baudrate upon which the Xpro Firmware is expecting? 9600 is working well on my tests so far.
     
  2. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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  3. Chris Robertson

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    Perfect Thanks.

    I've checked the schematic, but just for the sake of clarity. I will be able to use the TX(9)/RX(7) pins on the Aux Header as a 5v UART from the Microcontroller for this (There wont be anything on the XBee/USB port)? 1st glance I will need to get 5v power from elsewhere, non of these other pins on JP9 will provide a couple of mA power will they?

    upload_2019-11-15_11-53-58.png
     
  4. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Correct

    Don't have the schematic open, but doesnt the Endstop headers have a 5v pin for powering active endstops?
     
  5. Chris Robertson

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    VM_OUT(1) carries the VM voltage 12-24V.
    I could use the endstop 5V but I'm already using that for powering a relay that triggers from the SPINDLE Enable. For neatness sake I am going to take the VM_OUT and regulate the voltage to 5V, gives me options further down the line too.
     
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  6. Chris Robertson

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    Hi, So I'm making progress but I am having to resort to a baudrate of 9600. However the OpenBuilds CONTROL Software wont connect when flashing the XPRO V3 to 9600. Can see the basic console output on PuTTY fine. Is OpenBuilds CONTROL fixed at 9600 baud?
     
  7. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    CONTROL's role is to be the easy, get you started host, asks as little questions just to get new users into the game without having to know hard stuff like what does baud rate mean, etc.
    Once you start outgrowing the defaults you would also have to look for a different host then, some of them do allow custom baud rates, but for the most part, Grbl has been 115200 for about 4-5 years now so most just hard codes it.

    9600 baud was used by Grbl 0.8 but that led to buffer starvation, so its probably not going to be good for you either :)
    Consider sorting out the HF start (I run a 40A chinese HF plasma, and use USB, 115200, etc, it can be done) by adding Ferrites to every cable, space plasma wires away from controller, properly ground the plasma, etc
     

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