STMicro Drivers

jb77
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Re: STMicro Drivers

Post by jb77 » Sun Apr 29, 2012 8:13 am

This driver looks very promising.
As a stronger platform i suggest some, which are arduino shield compatible.
Like olimexino stm32, or netduino.

I am gonna take a deeper look to this driver in combination with that olimexino.
http://www.olimex.com/dev/olimexino-stm32.html

But that will take a while.

This would be a lot of work, but the benefit would be great.

orcinus
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Re: STMicro Drivers

Post by orcinus » Sun Apr 29, 2012 1:00 pm

Netduino sounds like a bad idea. To me at least.
.Net and similar languages/environments aren't real-time and offer 0 guarantee that things will happen when you expect them (or time them) to happen. Even when this is not true, they tend to have significant latencies.

MLange
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Re: STMicro Drivers

Post by MLange » Sun Apr 29, 2012 2:27 pm

Shapeoko #280 (Inventables Batch #1)

bkgable
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Re: STMicro Drivers

Post by bkgable » Sun Apr 29, 2012 3:02 pm

The L6470 has a pretty standard SSOP-28 package so with a few breakout boards it could be prototyped on an Arduino shield which I am in the process of doing. STMicro has a GUI to try out the L6470s various registers but it requires some sort of Cortex M3 interface board.

What I would like to see is a board with three L6470s and some kind of QFP100 dedicated motion control processor. Question is which one. The XMega and Cortex A8 M4 have some dedicated motion control hardware like quadrature decoders. The TI Piccolo™ C28x 32-bit processors have special control law accelerators.

The processors all cost about the same so the choice would seem to depend on which have the best motor control software.

alpha
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Re: STMicro Drivers

Post by alpha » Sun Apr 29, 2012 4:13 pm

For me the most important thing is cost, I want to support something the poor and students can afford too (and something I can buy without my wife giving me a talk :))
It also needs to be very powerful and easy.
MLange wrote:Interesting idea, though I doubt the Raspberry Pi will be available to the average Joe every-person (who hasn't pre-ordered) for a fair while yet. There is also the BeagleBone, Beagle Board, Pandaboard, etc. I'm not sure where the most benefit lies between a completely computer-controlled Arduino, a completely self-sustainable computer with monitor, keyboard, etc (Pi, Beagle, Panda, etc), or somewhere in between, with an Arduino or Pi/Beagle/Panda and a limited UI. The sweet spot will definitely vary from person to person.
As far as I understand this is now at a different levels, looks like soon (2-3 month max) this item will be available like apples at Walmart. The first batch was 10,000 units but 300,000 pre orders. But now two large distributors strarted continues production and there is talk to lift the 1 per person limit soon. Looks like the distributors should be able to get all the pre orders filled by June-July. But maybe I'm to optimistic, however time is going by so fast that I'm sure it will be largely available 3rd quarter this year. For the poor the just one board would be better because same price. You can get a Arduino for $20 but you will be able to get the PI without Ethernet for $25 - TV out will just enable much more people on the planet to use it. You can build a cheap PC for $150 to $250 depending on the deals you can get a the time. Looks like we will see some other ARM stuff from China soon, I guess some board with a allwinnerA10 or something like this will be competing with the PI next year.
MLange wrote:With the majority of the processing offloaded to the drivers, even a 328 would have no problem driving an LCD-based UI with SD card slot for G-code files, or even Ethernet.
This is true and a good point, that's why a generic concept that can connect to a lot of different platforms would be best.
MLange wrote:Modular would be interesting, though I'd imagine having controllers chained or wired to some form of base hub would introduce some interference; If possible, you'd want connections to be direct to the arent board, and barring a direct connection, you'd want the cables to be shielded. (Hmm. Cat6 Shielded? I digress...) That being said, I could see some kind of shield (an Arduino regular or Mega shield / Beagle Cape / Pi Shield / whatnot) with driver daughterboards attached vertically to allow for airflow/heatsinks on each, as well as a port for remote-mounting of the drivers, such that you could mount them directly and/or remotely. Thoughts?
However you connect the daughter board it needs to be the lowest acceptable way. PCB plug in connectors like ISA bus are to expensive but very elegant. Cheap little 4 wire connectors like seeed grove uses may not up to the task? I don't know. RJ45 and twisted pair CAT 5e cable? Or over ribbon cable? Or serial cable. What is widely available and cheap and works good?

MLange
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Re: STMicro Drivers

Post by MLange » Mon Apr 30, 2012 12:03 am

alpha wrote:However you connect the daughter board it needs to be the lowest acceptable way. PCB plug in connectors like ISA bus are to expensive but very elegant. Cheap little 4 wire connectors like seeed grove uses may not up to the task? I don't know. RJ45 and twisted pair CAT 5e cable? Or over ribbon cable? Or serial cable. What is widely available and cheap and works good?
Well, if we're going to make a shield with just connector(s) off the board, there will likely be room for vertically-positioned boards as well. I'd imagine the easiest way would be 2x10 or 1x10 pinheaders (for cheapness/easy to source-ness) or an IDC socket (for fool-proof polarization), and right-angle connectors on the sub-boards, similar to what is done in Gerald's reprap board. (Fair mention: I got the idea for vertically-mounted boards and right-angle pin headers from there.) If that was an option, I would suggest I/we coordinate with Gerald to use the same pin-out for the vertical driver boards so as to create cross-compatibility.

Wire connectors like Seeed's Grove kit are nice, however you would likely need beefier (or more) connections for the power to the motor, and you'd also need a CS, CLK, SDI/MOSI and SO/MISO, so at the bare minimum, you're looking at 6 wires. Seeed's Grove system uses I2C, as opposed to the SPI that these chips use :geek:
bkgable wrote:The L6470 has a pretty standard SSOP-28 package so with a few breakout boards it could be prototyped on an Arduino shield which I am in the process of doing. STMicro has a GUI to try out the L6470s various registers but it requires some sort of Cortex M3 interface board.
Hm, you're right. I totally had a blonde moment :oops: Getting a SSOP28 breakout board would definitely be cheaper than making a run of SSOP28 Arduino shields :mrgreen: It would be important, though, to find one that has the thermal connection for the pad on the bottom of the chip.
alpha wrote:For me the most important thing is cost, I want to support something the poor and students can afford too (and something I can buy without my wife giving me a talk :))
It also needs to be very powerful and easy
I hear that, definitely. And yes.
bkgable wrote:What I would like to see is a board with three L6470s and some kind of QFP100 dedicated motion control processor. Question is which one. The XMega and Cortex A8 M4 have some dedicated motion control hardware like quadrature decoders. The TI Piccolo™ C28x 32-bit processors have special control law accelerators.
Okay, as a standalone product, I'd imagine? Keep in mind that the L6470 does contain a certain amount of motion control in and of itself.

Q: Should I/we start wiki pages to expand on each of these ideas? (Single-Board Controller, 6470 *duino Shield (and/or ATMega Board), L6470 Driver Module, Raspberry Pi Shield, etc? There are a number of good ideas, and I'd hate for any of them to fall by the wayside.)

(Whew, that's a lot of replying. Hope I got it all straight :mrgreen: )
Shapeoko #280 (Inventables Batch #1)

bkgable
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Re: STMicro Drivers

Post by bkgable » Mon Apr 30, 2012 2:34 am

MLange wrote:
Okay, as a standalone product, I'd imagine? Keep in mind that the L6470 does contain a certain amount of motion control in and of itself.
Your point is well taken....what does the software have to/can do that the L6470 cannot. Need to look at the grbl code in more detail.

MLange
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Re: STMicro Drivers

Post by MLange » Mon Apr 30, 2012 6:14 am

Here is the lineup of ST's Microstepping drivers

As an aside, the L6474 (EasySPIN) seems to be the version that would be most like the A4988, with STEP and DIR pins, though it does still have SPI pins to read/write to the (fairly limited) registers available, enable, or hi-z the motor(s). They come in TQFP64 at $8.62 USD for QTY=1 from Digikey US. If someone were trying to make a replacement A4988 module, this would likely be the nearest ST equivalent to the A4988 IC.

The L6460 (FlexSPIN) would be useful if you needed to drive 1 or 2 regular DC motors along with a stepper

All that is different, of course, from the L6470 (dSPIN), which is "state-of-the-art", with motion control, etc. easySPIN < FlexSPIN < dSPIN
Shapeoko #280 (Inventables Batch #1)

bkgable
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Location: Lexington, MA

Re: STMicro Drivers

Post by bkgable » Mon Apr 30, 2012 2:47 pm

The L6470 is $10.27 qty 1 from Digikey. Not a lot of difference for a $200 machine.

One thing that caught my eye about the the L6470 is the voltage mode as opposed to current mode. The pulses are done at a constant periodic rate in voltage mode which should make coordination of two axis easier. Also the leading edges of the current steps are smoothed. See page 6 in the ST presentation below http://www.st.com/internet/com/SALES_AN ... g_pres.pdf.

I have a HF mini-mill I'm converting to CNC (while I'm waiting for the Shapeoko to arrive). Cutting aluminum on the mill can generate some significant resonant vibrations depending on the cutter speed and feed rates. And that is with 150 lbs of cast iron. I expect the Shapeoko will need some "smart" stiffening to cut aluminum and smoothing the current steps would also help. This is still to be tested as near as I can tell.

Also the 7A peak and 3A average would be very good for NEMA23s.

edwardrford
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Re: STMicro Drivers

Post by edwardrford » Mon Apr 30, 2012 3:40 pm

bkgable wrote:.... I expect the Shapeoko will need some "smart" stiffening to cut aluminum and smoothing the current steps would also help. This is still to be tested as near as I can tell. ...
Hi All!

I don't want to hijack this thread given how productive it appears to be. Instead, I posted a reply to this, on another thread, found here: http://www.shapeoko.com/forum/viewtopic ... 1260#p1260
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

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