Duet 3 Mainboard 6HC - initial production run.


  • administrators

    @deckingman yes 4A but RMS now. David has tested over 4A RMS but I will keep the claim to 4 for now until we have done more testing


  • administrators

    @danal @Dougal1957

    We still have some of the first batch unallocated. When we have sold out of that production run it will be out of stock on the website.

    The "normal" production run later this year will not be a pre-order.

    Cheers

    Tony



  • @t3p3tony said in Duet 3 Mainboard 6HC - initial production run.:

    ...yes 4A but RMS now.

    Does the gcode current limit now instruct the drivers to maintain an RMS value or use the value as a limit to chop the current at?



  • Judging by the post on ecoansion board testing 4A RMS is roughly 5.7A peak, but I guess the exact relationship between RMS and peak will be related to drive voltage and the electrical properties of the motor.

    If the Duet 3 does still control at peak current does it report RMS or was that just read off the test rig equipment?


  • administrators

    M950 motor currents in RRF have always been peak. This is because when the original Duet 0.6 came out, instructions for setting potentiometers on stepsticks were given in terms of peak current, probably because the Allegro drivers that were generally used referred to peak currents in the datasheet.

    Trinamic mostly refers to RMS currents in their datasheet. Somewhat confusingly, Marlin has adopted RMS current in its current-setting commands for Trinamic drivers, even though builds of Marlin for boards with non-Trinamic drivers that support motor current setting (e.g. RAMBO) have almost certainly always used peak current.

    The maximum allowed M906 value in the latest RRF3 builds for Duet 3 is 6300.



  • @dc42

    I am probably slow here but I have read the hardware overview and it is not clear if a Raspnerry Pi I needed to use the web interface?

    Has the duet 3 network.connectivity on it's own, wired or wireless?

    The hardware overview states the following, and what is referred as "It" marked in bold? The duet 3 or a Raspbeery Pi.

    The Duet 3 mainboard has a dedicated high speed SPI bus to a single board computer (SBC). The reference implementation is a Raspberry Pi 3B or newer. The SBC provides the user interface (via a browser based control application called Duet Web Control, or a third party application). It also provides a network interface via the local network or VPN depending on how it is configured.


  • administrators

    @fotomas The Ethernet network interface is mainly there for future support for EtherCat. and also for people who it does not make sense to use a SBC (like the OEMs that David mentioned that have multiple Duets controlled directly from a single computer). It would be possible to use the Duet 3 without a SBC, and just use the Network interface (assuming the uSD card holder is populated), but we are not recommending it because you loose out on all the development we are planning for the SBC (e.g better UI performance, better networking and plugins).



  • @t3p3tony thank you.



  • Is it possible to power the MCU from EXT 5V (to allow it to shut off motors and heaters by turning off the 24V PSU), or has that been replaced by the SBC->5V setup?



  • @martink said in Duet 3 Mainboard 6HC - initial production run.:

    Is it possible to power the MCU from EXT 5V (to allow it to shut off motors and heaters by turning off the 24V PSU), or has that been replaced by the SBC->5V setup?

    That's still possible.



  • @wilriker Great, thanks for confirming!





  • @knaudler Potential cost issues apart these are better. No loosening issues as the springs keep the correct loading on the contacts.



  • I've already bought my board (looking forward to it!). I totally didn't even read the specs before buying so I'm now catching up on the whole SBC thing. 🙂

    So, with the new SBC interface, does that mean that the PanelDue is deprecated? Is/will there be another touchscreen replacement to fill the gap?

    Also, is there any reason to avoid or go for a Pi 4 over the 3+?



  • @leonmf said in Duet 3 Mainboard 6HC - initial production run.:

    Also, is there any reason to avoid or go for a Pi 4 over the 3+?

    I just got my hands on a 2Gb Pi 4 and I'm quite pleased with it. The biggest improvement IMO is the change to the ethernet and USB ports. In the Pi 4 you get actual gigabit ethernet speeds and actual USB3 speeds, whereas with the Pi3b+ the ethernet port was hung off the USB hub and shared their limited USB2 bandwidth. It made certain i/o tasks painful.

    The big CPU upgrade is nice as well as the added ram. I doubt that will really become critical for running the duet, but given the minor cost disparity, I would say that the Pi 4 will have more longevity, especially if you ever wanted to repurpose it.



  • @leonmf In addition to what @Phaedrux said the requirements have been changed to "RPi 3B or newer" which of course also includes the latest RPi 4B. Maybe the product page has not been updated after that change.

    This originally simply was because at the time prototyping tests began RPi 3B+ was the most recent version.


  • administrators

    @leonmf in addition to the good points about Raspberry pi versions already made, regarding the screen: The idea is that there are a multitude of HDMI and direct interface touch screen available for Raspberry Pi so you have much more choice. at the simplest level you can have DWC running on the touch screen in a maximised browser but i am sure there will be a range of UI options developed to suite different screen and requirements. The advantage of doing this on the SBC is its much easier to make UI changes than on the PanelDue.



  • Thanks everyone!

    @T3P3Tony I had this argument with the M3D team when they argued that the PanelDue was a waste of time. 🙂

    The PanelDue is certainly limited in what it does and how it operates but that's part of the benefit. Fundamentally, it just works and the M3D argument of buying a cheap tablet and using it as a UI completely missed the point that you just need the ability to poke a jog or home button without the drama of maybe the tablet went to sleep or the UI wasn't built for touch.

    But... if you're saying that there will likely be a touch friendly UI that works with the SBC and the SBC being operational is required for the unit then I likely have little to complain about!



  • Posted in a separate comment for clarity.

    Some time ago, I used to run my home automation system on Raspberry Pi. Then, after that, I ran my home audio on Raspberry Pis. They did work pretty well but were more prone to corruption than I'd like.

    The beauty of an embedded board like the Duet 2 is that powering it down and back up meant that it was still going to come back up fine.

    My experience with Raspberry Pis were that they are a full OS and don't particularly love being shut down without going through a clean shutdown. Something that a device with an off-switch isn't all that great for. Perhaps my early experiences with Raspberry Pis reflect a fear about dirty shutdown corruption that isn't a reality any more. Do I have any reason to be concerned on this or are my fears several years out of date?



  • It will be fun to see the improvement but I don't fancy the idea of a SBC at all. I kinda need it for the stepper drivers on nema 23s.. Time will tell if SBC was the correct decision I guess 🙂


 

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