Announcing the ORDuino !

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Re: Announcing the ORDuino !

Postby frob » Thu Mar 01, 2012 9:47 pm

butterfingers wrote:You might want to consider something like this:
http://www.goodluckbuy.com/3-2-tft-lcd- ... duino.html
http://www.goodluckbuy.com/2-4-tft-lcd- ... duino.html
That would be very cool.


Yes i agree a full graphic TFT would be very cool!
These are designed to clip onto an actual Arduino Mega board, and i suspect you'd have too many signal conflicts to make it work at the same time as a RAMPS without a lot of rework
- and then i'd be concerned about the ease of generating graphic screens and content to actually make use of it.
The Arduino in my opinion is not really amenable to that.
But not to worry, there is hope. I am already scheming a 2nd revision of this board with a Cortex M3 core processor instead that can drive TFT's directly and supports the dot-net microframework, making GUI design a snap for anyone that knows C# & visual studio. Plus Ethernet and a host of other stuff. and the TFT will be a 7" 800x480 touch screen.
But that will be later - i have lots in the pipeline before i get to that, and porting the firmware over may turn out to be a pretty big job, so i have no idea if/when i will actually get round to that.

But ORDuino is happening now! and getting a simple serial monochrome LCD going with bitmap fonts and simple graphic icons is pretty easy.
Thats as far as i'm comfortable going with displays at the moment so as not to slow down development - i can't afford to spend much more time on it now unfortunately.
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Re: Announcing the ORDuino !

Postby dzach » Thu Mar 01, 2012 10:06 pm

The Raspberry Pi is an ARM SBC and has 54 GPIO lines. It also has an unbeatable price $25 for model A $30 for model B (1 additional USB and an Ethernet port) in addition to all other features, like 256MB of RAM, video, audio, SD card etc. Have you considered using it?
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Re: Announcing the ORDuino !

Postby frob » Thu Mar 01, 2012 10:16 pm

dzach wrote:This sounds really interesting at that price. I'd like to see the LCD interface included as well as the ATX connector, although this might mean the 160x80 size will become unavoidable.
Some questions:
- Are the SD card and (optional) LCD display going to be supported by the software?
- Does the software support the new current limiting capabilities of the A3988 driver?
- Is the PCB going to be a 3layer one? Alegro MicroSystem recommends it as a low point ground and thermal path.
- The chip manufacturer gives a 1.2A per phase current rating, i.e. 2.4A per axis. How is the 3A max achieved?
Considering the combined heated bed + ORDuino PCB, could that be a kit with all SMT parts (including the ones for the heated bed) pre-soldered and all the non SMT parts supplied with the uncut PCB?
That would make it an unbeatable offer (at present at least)for the ORDuino + heated bed!


Cool, thanks for the great feedback!

My understanding is the SD card is already supported in the current popular Arduino firmware that supports RAMPS, as the "SDramps" add-on card is pretty popular. It uses the SPI interface, which will also be used to control the LCD and motor driver settings, so some small additions to the code will be necessary to multiplex all 3 on the same spi port. this is a fairly trivial programming exercise though.

I'm not planning to use the A3988 or any other part from Allegro. I was lookign for another IC, and i briefly considered the a3982 (almost identical, slightly different package) because you cant find any for sale, they are deeply backlogged due to popular demand, and now the 3982's are pure unobtaineum as well. there's plenty of 3983's (same but 1/8 microstepping only) at Digikey at the moment but that could change at a moment's notice.
In the end i found and chose a part that is vastly superior in almost every way except price. - its slightly more expensive, but worth it- its a new part just being released but i have parts and the factory tells me they have over 122,000 of these parts available - not likely to run out any time soon. its one of the top 10 US semiconductor companies and they have really excellent support & documentation, i would put them as #1 in that respect.
The PCB is 2-layer only to save cost, that's why it is physically larger and more spread-out, but will have 2Oz or 3Oz copper. There's no such thing as a 3-layer board- the next step up is 4-layer, then 6, etc. they're done in pairs to prevent board warp, and the process just works out better that way- 3-layers would be more expensive than 4 and cause issues as a result.
I make my living designing boards and i'm an expert / consultant with Altium so i can promise the layout will be top notch and really well engineered from an thermal, EMI, susceptibilty, and assembly point of view. If you're interested i can tell you its really 2-1/2 layers in the digital section - most of the signals route on the top layer, so the bottom side is mostly solid ground plane with carefully controlled perforations to bridge signals on top or small power islands. I routinely do mixed-signal analog /digital / power / RF designs (to 2.4G) this way and have never been disappointed with the results. But i'm not afraid to do a 6- or more layer board when necessary ;)
Bottom line is, you can do a lot with good board layout and thermal considerations, but the best approach is to just not generate the heat in the first place - so: very low-RDS-on mosfets, small or no current sense resistors, switching vs linear regulators, etc. Which is that i've done first with this design. Result is less than 1/2 the power dissipation to begin with vs stock ramps+ pololus


Thats an interesting idea to sell it as kit with through-hole parts unmounted.
i'll consider doing that for the initial run but not sure what if any savings it may produce ,because only a few of the optional connectors are actually through hole, everything else is SMT - my thought was to have a "vanilla" version with only SMT / basic connectors, and a couple of other SKU's with optional TH connectors like ATX, DIN, Mini-Fit, or some TH Faston tabs (they take much less board space).
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Re: Announcing the ORDuino !

Postby Zat German » Thu Mar 01, 2012 10:36 pm

Make sure you give us a way to access the i/o pins that are not being used for RAMPs-firmware support. I know it makes it a bit bigger, but I would prefer if it gave us a ground pin for each i/o pin instead of a single ground and a bunch of i/os like on the current RAMPs shield. It makes it easy to add additional things for those of us that want to modify firmware for custom stuff.
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Re: Announcing the ORDuino !

Postby frob » Thu Mar 01, 2012 10:56 pm

dzach wrote:The Raspberry Pi is an ARM SBC and has 54 GPIO lines. It also has an unbeatable price $25 for model A $30 for model B (1 additional USB and an Ethernet port) in addition to all other features, like 256MB of RAM, video, audio, SD card etc. Have you considered using it?


Interesting, i'll check it out later, but the short answer is no - and i probably wouldn't mostly due to software and supply chain considerations.
Once your hardware is cheap enough and not limiting performance, its the software that becomes the bottleneck , in terms of development, and by far dominates the time / cost of design. For that reason, its usually best to stick to what's familiar unless you cant get there from here.

The Atmel IC costs a whopping $22 in small quantity, and $12 in volume. not great value by today's standards-
The Cortex parts i'm familiar with and will do a version with later, can do everything i could imagine i would want from them and more and cost half that much , with 100x the performance and 2-4x the flash and 10x the ram-
including things i consider essential for this type of application - running a real RTOS, or full GUI, or both at the same time even - with real DSP capabilities, advanced internal motor control peripherals, and lots of open-source code support - Linux if you like, or Android, etc... plus Ethernet, host / fast usb, etc, etc, etc...

- so < $10 vs $22-$25-$30 and a software environment that's very familiar, easy to develop with, i have already written lots of useful code for, open source, and extremely popular outside of the hobby space.

- in the end its usually cheaper, easier, and safer for me to use an IC than someone else's board level module.
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Re: Announcing the ORDuino !

Postby frob » Thu Mar 01, 2012 11:11 pm

Zat German wrote:Make sure you give us a way to access the i/o pins that are not being used for RAMPs-firmware support. I know it makes it a bit bigger, but I would prefer if it gave us a ground pin for each i/o pin instead of a single ground and a bunch of i/os like on the current RAMPs shield. It makes it easy to add additional things for those of us that want to modify firmware for custom stuff.


Hi Zat,
we'll i'd like to, but the fact is pretty much all the IO's are used up already! there's four 3-pin servo headers already that you could use, and maybe in the end half a dozen or less unassigned io pins. The space around the CPU is very densely packed, so not much room for extra headers -
I will bring out any unused pins to a largish via if i can, and line them up on a 50 thou or 2mm grid if space allows, but adding a ground pad next to each one probably isn't practical.
I'll do what i can but remember this is really the anti-arduino as its really not meant to be a general /expandable experimenter's platform.
That is what allows this to be cheaper and support more capabilities at the same time.
If a versatile platform is really what you prefer, you might be better served with the existing RAMPS+Arduino+pololu stack.
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Re: Announcing the ORDuino !

Postby Zat German » Thu Mar 01, 2012 11:30 pm

Oh right, I forgot about that. I can just use my RAMPs for experimental stuff then and use this for a super tidy ORD bot. :)
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Re: Announcing the ORDuino !

Postby dzach » Thu Mar 01, 2012 11:56 pm

frob wrote:My understanding is the SD card is already supported in the current popular Arduino firmware that supports RAMPS, as the "SDramps" add-on card is pretty popular.


You are right. I wasn't sure about it, but now I see that at least Sprinter supports printing from the SD card.
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Re: Announcing the ORDuino !

Postby chiman » Fri Mar 02, 2012 3:28 am

frob wrote:... so please dont be shy to give me your opinion and suggestions right away!


Good idea to integrate improved electronics onto a single board, at least for the initial run. Reduces costs, makes things simpler for early adopters.

Eventually, I'd like to see the printer be network-aware. WiFi 802.11 a/b/g/n would do.
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Re: Announcing the ORDuino !

Postby frob » Fri Mar 02, 2012 4:08 am

chiman wrote:...Eventually, I'd like to see the printer be network-aware. WiFi 802.11 a/b/g/n would do.


Good idea! eventually , that's what i will do :)
I already have IP networking up and running in other projects both on 10/100 Ethernet and WiFi. This using a full IP stack not one of the "lite" stacks that allow only one connection or 1 packet at a time; i can feed and read at full wire-speed to a thousand ports if necessary. And host USB reading of flashdrives, of course, those use a non-arduino compatible Cortex M3 processor. The newer parts have built-in high-speed USB with tranceivers even so as a direct attached printer very large files should come across in a flash. Streaming video over IP from a cheap usb webcam has been done with the same microframework platform which should come in real handy for remote monitoring a networked 3D printer, or running remote (pc-based) image processing for a pick & place machine.

I'm using FreeRTOS in some projects and dot net microframework in others, especially when a GUI is involved. We're about to start a special port of both together, which should really rock for this sort of application.
I would port the basic 3D printer core as a set of cooperating FreeRTOS tasks (C/C++, totally deterministic, preemptive, nano-second timing) and the GUI, G-code / PostScript interpreters / STEP slicer under microframework (C#, visual studio dev) and let them interact through semaphores and ramdisk files. eventually i'd like to be able to directly send step files to the printer and have them sliced up automatically in the controller - the DSP vector/matrix operations & 32-bit floating point in the Cortex M4 @ 204MHz should make this feasible. and the built-in TFT controller makes an elegant GUI feasible too. amazing what you can get in an $8 IC nowadays eh?

Any interest in CAN or RS-485 networks? CAN is built-in to the Cortex part and there's a free CANopen stack available.
i know its used a lot in factory automation.

RS-485 is something i use a lot so its easy cut n paste.

Other than that i can easily do bluetooth, zigbee, and my new favorite, SNAP (esp at 900Mhz), for wireless networking.
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