Duet hardware actually makes it into Thomas Salanderer's videos

JRDM

What I'm seeing on the Maestro looks pretty good. If anything, I think the preorder price will add a lot of new people to the Duet platform. Hopefully the retail box price can go down

The interview mentioned fuses on the Duet 2's thermistors. I go to the latest schematics on Github (Duet 2 v1.03) and I don't see any fuses on the thermistor circuitry. I see some resistors and small caps but no fuses.

Then there was talk about protection circuitry to protect against motor disconnections, and the closest I see is 1nf caps on the motor connectors. I would have expected to see a gaggle flyback diodes for driver protection. Trinamic data sheets don't seem to mention flyback diodes or even show them built into their motor output FETs.

Am I missing anything?

dc42

@mysta, I am already running a RTOS build of RRF on a Duet Maestro in one of my printers. The SAM4S8C on the Maestro has the same amount of flash memory and RAM as the SAM4E8E on the Duet WiFi/Ethernet, so the RTOS build will become the standard firmware for it.

@JRDM, there is a PTC fuse between VSSA and ground. The driver protection comprises the 1nF caps along with careful PCB layout, to limit the dV/dT seen by the mosfets and hence avoid parasitic turn-on. My testing has shown this to be adequate, see https://www.youtube.com/watch?v=uyWolKFzb-A. All stepper motor drivers include flyback diodes.

JRDM

@dc42 OK well Trinamic's data sheets don't mention it or show it in any of the circuit diagrams. I know Allegro shows them in their circuit diagrams but doesn't mention them.

But setting that aside, what are you doing on the drivers that works so well? The video is impressive.

BenDiesel

hey you might take a look at what thease guys are doing for the bldc with encoder
https://odriverobotics.com/#odrive

OG3D

@dc42 said in Duet hardware actually makes it into Thomas Salanderer's videos:

@og3d said in Duet hardware actually makes it into Thomas Salanderer's videos:

@dc42
Is implementing closed loop support in hardware and software by an encoders on your radar for next version of duet?

We've been keeping an eye on developments in this area, with a view to doing an alternative DueX expansion board that would drive BLDC motors instead of stepper motors. The main problem so far is the lack of suitable inexpensive BLDC motors. The cheap ones used in quadcopters have no gearbox and no sensors, which is OK when you only run the motors at high speeds, but no good for 3D printers. When we need is a BLDC motor with built-in commutation sensors (so that we can run the motor at low speeds), a reduction gearbox (because BLDCs are only efficient at high speeds), and that gearbox must either have very low backlash or else we also need an encoder on the output shaft with a resolution of at least 5000 counts/rev.

@dc42
What do you think about them?
https://hackaday.io/project/11583-odrive-high-performance-motor-control

I was more think of adding support for encoders.
Something like this one.
https://www.cui.com/product/product-resources/amt100-series-modular-encoders.pdf

dc42

@og3d said in Duet hardware actually makes it into Thomas Salanderer's videos:

@dc42
What do you think about them?
https://hackaday.io/project/11583-odrive-high-performance-motor-control

It looks good, but way overpowered and too expensive for ordinary 3D printers. It might be good if you wanted to print a house though!

T3P3Tony

@vlad said in Duet hardware actually makes it into Thomas Salanderer's videos:

Oh well, that's not a review unfortunately. But still nice to hear some news. Hoping he will actually review the board. Maybe he didn't review it because Duet3D folks did not offer him a board? Could be a reason.

We have offered him a board but Tom has a lot on right now!

Vlad

@t3p3tony I will try to ask him on Patreon, I am one of his top supporters there I would actually love to hear his opinion on this board. I am sure many folks will enjoy such video.

Cata

He has a duet, we see in one of the videos about drivers

Nice img
alt text

T3P3Tony

Thanks, and yes we sent him a Duet.

OG3D

@dc42 said in Duet hardware actually makes it into Thomas Salanderer's videos:

@og3d said in Duet hardware actually makes it into Thomas Salanderer's videos:

@dc42
What do you think about them?
https://hackaday.io/project/11583-odrive-high-performance-motor-control

It looks good, but way overpowered and too expensive for ordinary 3D printers. It might be good if you wanted to print a house though!

Agree, but image how fast the speeds can become.

raykholo

@dc42 said in Duet hardware actually makes it into Thomas Salanderer's videos:

All stepper motor drivers include flyback diodes.

Can you elaborate on this? I have not seen any flyback diodes on the Duet Wifi nor on the Maestro anywhere near the motor drivers.
So is this something that is internal on the TMC2660? What about the TMC2224?

I ask because we did manage to kill a TMC2224 by the motor cable coming unplugged while energized on a recent prototype board. I would appreciate any tips on how to make the drivers more robust in this scenario.

dc42

What I meant to say was that all stepper motor driver chips include flyback diodes. They are built into the output MOSFETs.

There is a section about protecting drivers on the TMC22xx datasheet.