On Thu, Mar 12, 2020 at 1:41 PM John Dammeyer <[email protected]> wrote:
> Hi, > > I've been proposing something very similar that would use a BBB or a PIC32. > The reason for the PIC32 is the lack of I/O on the Beagle once you enable > the HDMI or plug in one of those small 4.3" LCD displays. > > > > I already have a 4DCape (attached JPG) and a Replicape c/w with poorly > functioning Manga Screen. I bought the newer Manga screen but as yet > haven't really done anything with it or the Replicape. > > > > I've also got an earlier xylotex DB25 cape and a LogicSupply Serial cape. > Unlike say the ISA bus on the original PC, nothing is really compatible so > they can all plug in at the same time which makes sense because the BBB > external connections aren't really an expandable bus. > > > > OK. So what does a CNC system need? I think it's always better to first > specify the needs and then see what processor fits rather than insist on a > particular architecture and then shoehorn in the specifications to fit the > target hardware. > > > > 1. Either 4 or 5 axis step/dir. > > a. At a minimum X,Y,Z, A and B(or C) and up to 500kHz step rates to > handle some of the now low cost AC servos with 2500 line encoders. > > 2. Spindle control in the form of two outputs: > > a. PWM and Direction or > > b. Step and Direction or > > c. Relay Clockwise, Counter Clockwise. > > 3. Spindle Quadrature encoder input > > a. Differential A/B and Index high speed hardware for 2500 line > encoders turning up to 3000 RPM. > > 4. Home switch input for 4 or 5 axis (does a rotary require a home > switch). > > a. shared with Limit switch for each axis. > > b. Open circuit means activated. > > 5. Limit switch for the other end of each axis. > > a. Open circuit means activated. > > 6. ESTOP input with ESTOP asserted when ESTOP not connected. > > 7. ENABLE output. > > a. One active high > > b. One active low. > > 8. Coolant output control > > a. Flood > > b. Mist > > 9. General purpose output signals for power supply enables etc. > > 10. Charge Pump output that when stopped shuts off all outputs including > ENABLE. > > 11. USB input for a pendant of some type > > a. For USB stick for code or firmware updates. > > 12. Or at least Inputs for Quadrature encoder knob and a few buttons. > > 13. MODBus support with either RS232 or RS485 > > a. for something like a Homann Designs MODIO > > b. Other MODBus end products for things like tool changers > > 14. CAN bus with CANopen support > > a. for expanding to other hardware like tool changers. > > 15. Ethernet connectivity. > > 16. Some sort of display. Size depending on what level of application > is running on the BBB. > > > > Point 16 is the interesting part. Should this be a small 4.3" to 7" LCD > display serving as a rudimentary DRO and status display? Or should it be > the entire AXIS interface or something between. > For the inclusion of UI support, does it really need to be BeagleBone Black or can that be BeagleBone AI? Today, we need some software updates to run reliably without a fan, but I think that can be incorporated--unless you think a fan should reasonably be a part of the solution. BeagleBone AI does jump the price of the BeagleBone to $99 (assuming tariff situation is put under control with either a US source or the tariffs go away), but is that really significant for a CNC solution that includes the UI? BeagleBone Black can handle the UI, but could be considered generally be a bit sluggish on that, especially if the 3D accelerator isn't integrated nicely. > > > And with point 16 in mind, if the display makes the BBB into an > intelligent power feed DRO controller to allow essentially manual operation > on the mill then the Ethernet port could be used to connect a full size PC > (laptop or workstation) running LinuxCNC/MachineKit with full graphical > tool path display etc. > That seems like the sweet spot for BeagleBone Black to me. Still running Machinekit on the board, but running the UI remotely. > > > It's already possible to buy a CNC controller for $200 to $300 from China > with a 4.3" display, a bunch of buttons and a USB connection for loading > G-Code. And there are some users who swear by that solution as the > easiest and fastest way to get working. But they aren't open source. They > aren't expandable. > Exactly. How can we create a nice experience out of box like something purchased off the shell for CNC control, but keep it open and expandable. If $300 is the expectation with 4.3" display and USB port for G-Code, then let's work together to set the requirements appropriately. > > > To have all the above I/O requires a lot of pins. I'm not sure the BBB > can do this all. Unless it uses 10Mhz SPI to a serial shift register > latch to create 6 axis STEP/DIR/PWM for X,Y,Z,A,B and Spindle along with > coolant outputs to a maximum of 16 outputs. Since SPI is in and out the > system can just as easily hold a 16 bit latch that is shifted in at the > same time holding the various inputs except for ESTOP and maybe a MACHINE > ON switch. > > > > Some of the features on the PMDX-126 break out board could be part of this > cape. In fact the idea that perhaps a simple I/O bus structure be > designed in is a really good idea. A bi-directional 8 bit bus with a 4 > bit address bus along with RD/WR/ signals would allow LCD displays and > other external add on devices. The PIC32 for example supports that sort > of bus. I think the ARM on the Beagle does too but it may not be > available. > Worth exploring what we can do to effectively generate such an expansion. I think there are many options for it. > > > So this cape would look a lot more like a PMDX-126 but be that large BoB > cape for the Beagle. It would have the I/O and maybe even high voltage > relays along with optically isolated I/O. > > https://www.pmdx.com/PMDX-126 > > The photos show how the PMDX has an expansion bus and a set of connectors > that are compatible for a smooth stepper. > > > > Perhaps make the BBB the replacement for the Smooth Stepper and the cape > the replacement for a much more extensive PMDX-126. And use the BBB > Ethernet connection to be the interface, if CNC is wanted, to MachineKit > or LinuxCNC or even maybe MACH4 too. Give the BBB cape a display output > for rudimentary DRO and control information but for full CNC let a > processor like Raspberry Pi4 or PC with much better decent HDMI control > serve as the graphical and keyboard/mouse user input. > > > > The need for the BBB to do everything just doesn't exist anymore when that > Pi4 only adds $50 to the price and the display/keyboard/mouse are fixed > costs no matter what system is used. > I'd agree with that. The BeagleBone Black should really be valuable for its ability to act as the real-time controller, not as the UI. BeagleBone AI should be able to do both and also potentially introduce some kind of preventive maintenance modes, tough greater stepper driver/motor feedback would be needed. > > > Make the system stand alone and scalable so a user can first add just a > motor to their X axis for power feed. Six monts later the Y axis for > power feed. Then a year later the Z axis for power feed. When they > swap in a 3 phase or AC servo motor onto the spindle they suddenly have > on/off speed control and now the potential to add simple CNC operations. Some > of those could even be local like the wizards in MACH3/4. > > > > IMHO > > John Dammeyer > > > > > > > > > > > > > > > > *From:* [email protected] [mailto:[email protected]] *On > Behalf Of *Jason Kridner > *Sent:* March-12-20 6:39 AM > *To:* [email protected] > *Cc:* [email protected] > *Subject:* [Machinekit] Seeed to design and build Machinekit focused Cape > for BeagleBone Black/AI > > > > Seeed is looking to not only build a Machinekit-focused Cape for > BeagleBone Black and BeagleBone AI, but to: > > * Take in features and feedback from the community > > * Contribute the design to open source and certify it as such > > * Manufacture the design under the BeagleBoard.org name to support the > BeagleBoard.org Foundation and community > > * Help assemble and provide software images configured for an open source > 3D printer and CNC machine (with BeagleBoard.org and community guidance and > support) > > * Offer a collection of additional accessories which might commonly be > needed > > > > I am very excited about this because I know Seeed cares about open > hardware and also knows how to deliver solutions reliably and cost > effectively. > > > > So, what are your ideas about where to start on such a cape? > > -- > > https://beagleboard.org/about > > -- > website: http://www.machinekit.io blog: http://blog.machinekit.io github: > https://github.com/machinekit > --- > You received this message because you are subscribed to the Google Groups > "Machinekit" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/machinekit/CA%2BT6QPktUtnx5fv0AG%2BEqENM2mBRw44FLiEe-hKBRXOTanHomg%40mail.gmail.com > <https://groups.google.com/d/msgid/machinekit/CA%2BT6QPktUtnx5fv0AG%2BEqENM2mBRw44FLiEe-hKBRXOTanHomg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- https://beagleboard.org/about -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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