Reprap Electronics Devolpment

Krafter.

PWM is indeed on the backplane. Along with the most common IC to IC serial buses to drive off the shelf DAC chips, as well as enough digital IO to make your own boards featuring an R2R DAC. The choice is yours as an implementer as to how you want it.

On voltages, 12v and 5v are common and sensible voltages to have to all boards, the current carrying capacity is sufficient (due to multiple pins per voltage rail) for driving a machine. Puting anything beyond 12v on such a DIY backplane may be asking for trouble. The higher the voltage the less forgiving the consequences of an accident. Having said this you are quite right driving motors from much higher voltages can give benefits that an individual designer may want.

My best advice on doing this is to use your own choice of connectors on the non backplane end of the plug-in cards. (When working with higher voltages these should be specified & insulated to suit what you as a designer are choosing to work with) If someone wanted to drive 100v BLDC motors you really would not want 100v on the backplane.

On space, The backplane is a compromise in getting as much functionality into it as possible without going too mad with the connectors. A third row per connector is possible but increases the costs for something that the majority may not need and perhaps would be unsuitable to designers wanting a high voltage driven performance. Please do innovate and add whatever additional connectors you need to your plug-in cards. you have pretty much 3 sides of a plug-in card to work on. This should be plenty.

That is exactly what it is "a standard backplane." If we were coming at this from a greenfield point of view consensus would be arguably easier to achieve. It could be anything we want. It is specified around IO to ensure that the design does'nt limit what processor or microcontroler someone wants to use with it. Multiplexed Data/Address Bus, Non Multiplexed Data/Address Buss, 8 Bit Data, 16 Bit Data, 32 bit Data, How much address space, 16bit, 20 bit, 24 bit, 32 bit ?? The list goes on, If we specify a processor or system bus (as opposed to an IO buss) we are prescribing what processor/controller designers may use. Where we make it difficult or wasteful for a designer to work with us we loose a valuable contributer to the project.

We have a legacy situation to take into account as well as a sensible and affordable quantity of future to add in. It would be divisive to abandon all those (arguably currently the greater majority) who have a legacy, current and near future investment based on Arduino, Sanguino and Mega oriented hardware.

I would like to argue that we are best placed to achieve consensus by creating a newer way forward that is s super set of past and future.

In order to achieve this I have put forward a design which is a passive backplane IO Buss (actually if you wanted you could take the hardware and plug what you want into it, completely ignoring the suggested pin-out) which will be sufficient for everyone's needs and have some spare for experimentations.

Clearly you will get best bang for your Time & Buck when you work with the guidelines (if only because you can slot other designers modules into your system. Ultimately though the designs are given for free for you to do what you will with.

Dissidence, yes you are quite right, where do we stop adding and suggest that the designer makes places the additional connections on their plug-in boards as needed. It is always a difficult choice as to what you show horn into limited resources.

Hope this covers most of the questions posed.

One from me to you. In order to put more voltage rails on to the backplane, what would you like to loose?

A. Money for an extra column of connections that mostly will not be used ???

B. Some of that functionality we have shoe horned in, PWM, DIO, ADC, Serial Comms

C. Neither A nor B I will add simple connectors to the other ends of the boards I design as I make them.

Don't take this as steerage, if you would like me to change the the design (it is not cast in stone and it is for you all after all) I need to see some direction and debate....

At least sufficient to draw out a consensus that folk can sign up to. Without consensus it is actually a complete waste of time. Whatever it ends up like.

Hope this helps

cheers

aka47

Edited 1 time(s). Last edit at 02/08/2010 04:57PM by aka47.

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Necessity hopefully becomes the absentee parent of successfully invented children.

OK guys,

Please find attached the draft design for a 5 way backplane board from the earlier schematic.

5 ways should be enough for the average machine, and allows for some prototyping etc.

I can do designs for more ways and longer backplanes, it is realtively straightforward to do. In the short term, just make two back planes and link them together if you need more.

The design is for a single sided board so it should be doable from home if you don't want to send out to your most local board maker.

If you are not sure how to have a go from home there is a tutorial on my web site that should help, thi sis roughly how I prototype boards.

[aka47.adsl24.co.uk]

I hope to have all the designs in the RepRap repository soon (Note to self to remind sebastien)

Cheers

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

OK Guys

Please find attached the basic schematic and notes for the breakout and prototyping cards.

Actual board designs to follow as I do them.

Cheers

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

Ok Guys

Please find attached the single sided board layout for the breakout board. Not this is intended for one or a mix of:-

Soldering Ribbon Cable Headers to.
Soldering wire/cable direct to.
Soldering Screw Terminals withe a 0.1" or 2.54mm pitch to.

So you can connect other cards etc to the backplane without the need for a dedicated card. This should let you use legacy RRRF boards with the backplane model.

cheers

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

I have been busy.. /just re found this Thread.. boy has it been moving along at a pace..

Love the break out board just printed it to see if I can make one later as Its nigh on impossible to access the Mega pin out short of wire wrap.. onto pins.

Been fighting with KiCad think I'm just awful slow learning new SW packages.

Andy did you ever have a Map80 or Nascom2 system or the Nascom 1 with the bus adaptor.?

As with all Electronic designs there will be many many different views and valid solutions to solve the same problem. The style of each design is based on the designers experience in their field of work/expertise.

After I have sorted out this show thing ~ I will get a better read of this now quite long thread but it looks like a neat modular development system to push forward with lots of interesting future developments.

I believe that there should also be an instant gratification simple low cost user not interested in anything but having a 3d printer plug and play solution design as well. I know a lot of users just want the draw print type solution at least just to start with.

Once user like this come into the fold as it were (Adicted) a modular development system like this is looking like it might be is a nice step forward for every one.

I also see the huge advantages with using the IC2 RS485 / transputer type connection systems, I think though a simpler backplane/bus type system will generate a bigger variety of development. Which in turn could easily support a network like structure as and when designs are finalized and able to be moved off the backplane/RepRap Bus.

Great work!! my print out looks like my printer is good enough to put this on Lable backing papper to transfer to board...

Just ste follow topic so wont lose it again..

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Bodge It [reprap.org]
=======================================

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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

Bodgeit

I agree a one board solution like those from existing kit suppliers is great for those not too interested in the electronics. There is also I think an opening for a one board solution based on the 1280 (Arduino Mega chip) which one of the commercial providers might produce at some time. If only for the extra memory and IO that this chip supports.....

In the mean time as Zach & Bre pointed out in one of their many media features they are commercial kit producers and the Reprap project is all about Research and Experimentation.

Thanks for the vote of confidence it is much appreciated. Just working on the rest of the Prototyping boards (100 by 160 ish, a fairly standard size of bought in single sided copper clad board)

The designs at the moment are simply just that, designs. I am a touch busy turning them out at the moment to stop and build/print any. But hope to soon.

All are doable (professionally) but really need testing on the kitchen table. I am hoping that folk will help with the development and have a go, feeding back their observations and input. If we need to refine them a touch I will take that feedback as steerage to do it.

Hopefully moving the versions from 0.1 (Draft) to 1.0 (Release).

One of the prototype boards will have the tracks arranged suitably for mounting Surface Mount components (still single sided but using the copper side of the board for the SM components), I was planning to issue the first with a foot print that is compatible with the same micro-stepping controllers that the Pololu boards use. Unless someone wants to ask for another instead. This board then should make a great basis for developing a 2 to 4 Axis Stepper interface card.

Just waiting for repository access to make all the files available to everyone. Might need to put them up somewhere on my own web site in the interim.

cheers

aka47

Edited 1 time(s). Last edit at 02/14/2010 04:52PM by aka47.

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Necessity hopefully becomes the absentee parent of successfully invented children.

That's very cool, aka47.

Just waiting for repository access to make all the files available to everyone. Might need to put them up somewhere on my own web site in the interim.
I've created a space for them:
[objects.reprap.org]

I hope that is ok. Let me know when they need their own forum. I think you may have a different working title from "AKA47_Controller", but I am not very good with names.

Just waiting for repository access to make all the files available to everyone. Might need to put them up somewhere on my own web site in the interim.

I'll look into it. You may want to put them up on your own web site in the interim, but that may confuse future users.
[objects.reprap.org]

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{Edit: Rant deleted}

I apologize for the derail.

Edited 1 time(s). Last edit at 02/14/2010 09:00PM by SebastienBailard.

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Sebastien

Many thanks for sorting the space for us, much appreciated.

We are not great with names either and ended up with a working name of BEEF.

I am a little confused as to where to put all the kicad source files (schematic, net, stuff file, board files parts libraries etc) having had a rummage through the links, I was sort of expecting GIT or CVS or Source Forge or something.......

Help.....

I think I need a little guidance here, (it's probably me not getting something obvious) and am only too happy to fit in with what needs to be done to put all of this under the Reprap banner.

In the mean time the wiki space I think is going to be useful to write up some of the stuff that is currently sat in text files and in schematic notes along with the source files.

Don't apologize for a point well made.

I agree that the sources are very much of the project for the project etc.

Cheers

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

Many thanks for sorting the space for us, much appreciated.

I do get a thrill when people upload to the wiki. We even have a gear up there!

We are not great with names either and ended up with a working name of BEEF.
I've moved it.
[objects.reprap.org]
Now it sounds like something you bolt onto a cow rather than something you bolt onto RepRap user aka47's skull. (Further operational details of the latter are restricted to the ultrasupersecret core team mailing list.)

I am a little confused as to where to put all the kicad source files (schematic, net, stuff file, board files parts libraries etc) having had a rummage through the links, I was sort of expecting GIT or CVS or Source Forge or something.......

Help.....

I think I need a little guidance here, (it's probably me not getting something obvious) and am only too happy to fit in with what needs to be done to put all of this under the Reprap banner.

Likewise. Try using this.
[objects.reprap.org]

The Library and the ... git? ... the [[Official Repository]] are currently siloed. Uploads to the mediawiki don't get entered into git, or vice versa. This doesn't matter to Adrian or to people who live and breath svn, git, etc., but it does present a massive barrier to entry to non-code-monkeys who want a big Fat Upload Button.

[objects.reprap.org]

I'm using your contribution to help motivate this. I hope this is ok.

I have no idea how the operational details of mediawiki->git or git->mediwiki will work. But I know it is not going to involve me cutting and pasting 3 hours a day, when I could be replaced by a tiny shell script.

I'm also using your contribution to help motivate this. I hope this is also ok.

I'll get back to you about the [[Official Repository]].

---

Don't apologize for a point well made.
"Arguing kills uploads"
[www.metafilter.com]
(Elaboration deleted)

SebastienBailard Wrote:
-------------------------------------------------------
> Now it sounds like something you bolt onto a cow
> rather than something you bolt onto RepRap user
> aka47's skull. (Further operational details of
> the latter are restricted to the ultrasupersecret
> core team mailing list.)

Well, in terms of strapping it in, you strap the BEEF to your PORK, Piggy Back style.

Okay, maybe I'm just being silly, but well, it sort of works, -- PORK = Pluggable, One-microcontroller to Run firmware Kernel. Okay, maybe it doesn't work.

I'm just waiting for the Vegans and Vegitarians to start coming up with their alternative devices....

ARM Cortex M3 looks like the way to go! Because provides more processing power at less price than AVR on Arduino! And ARM have the same Open Source tools PLUS the debugger! And I think debugger is important for such big and complex systems that RepRap is!

I am being working a little with ARM from Phillips NXP and Atmel. NXP have some cheap and nice ARM Cortex M0 and M3.
The M0 goes to 32Kbytes flash and have a version with USB and not USB. The M3 goes to 512kBytes flash and have USB and Ehternet. Both runs at 100Mhz.

Opendous provides FULL Open Hardware based on this Cortex M3 and M0.

Starting from simple and cheap, here a LPC1313 Cortex M0 board, without USB (USB connector is just for providing power):


The same board but this time with LPC1343, which have 32kbytes flash and USB. It also have a USB bootloader from factory that presents as a USB flash disk, meaning that users can simple and quickly flash code, much more easy than Arduino!


And a board with LPC1758 Cortex M3:


Features

* based on LPC1758 ARM Cortex-M3 MCU
* Full-Speed USB (12Mbps) and Ethernet (100Mbps) capability
* USB-miniB and USB-A connectors and on-board GPIO-controllable TS3USB221 USB switch for USB Device and Host modes
* all pins not related to USB and Ethernet are exposed on the outer headers
* microSD connector in SPI Mode on the underside of the board
* 10/100 Ethernet based on the LAN8720 PHY
* Cortex Debug Header for JTAG/SWD
* 3.3V 1A+ +/- 2% ST1L05B regulator
* RESET button, NMI button, and USB status LED
* 12MHz main crystal and 32.768kHz RTC crystal
* Dimensions (LxWxH): 3" x 1" x 1"- plugs into standard solder-less breadboard
* completely OpenHardware Design, schematic/layout/assembly files available for Open Source KiCAD. Gerber and other technical files can be customized.
* Design is 2-layers with 7mil/7mil trace/space and minimum 15mil Vias

I had worked a bit in past with ARM9 at 200MHZ with 64Mbytes of SDRAM and etc, and I believe there is no need for such system!!! Also they are not ideal for low hardware control, as when we need PWM, ADC, motor control, etc... ARM Cortex M0 and M3 were made for that tasks, mainly to reach the market for the 8 and 16bits MCUs :-) -- the great are that ARM have Free Software tools and even better than AVR.

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New cutting edge RepRap electronics, ARM 32 bits @ 100MHz runs RepRap @ 725mm/s:

[www.3dprinting-r2c2.com]

Only drawback to this device I see is the 3.3V basis; I assume all the ports are 3.3V as well? This has the issue of being more susceptable to noise...

Any idea if there is a 5V equivilant, or alternatively, AKA47, any thoughts on using a alternative 3.3V + 12V lines for BEEF?

If I understand TTL correctly, 3.3V lines should be able to drive 5V TTL, but vice versa is a bit riskier? (I.E, driving a 3.3V input at 5V may cause issues?) Am I mistaken on this?

Edited 1 time(s). Last edit at 02/18/2010 10:19AM by BeagleFury.

BeagleFury Wrote:
-------------------------------------------------------
> Only drawback to this device I see is the 3.3V
> basis; I assume all the ports are 3.3V as well?
> This has the issue of being more susceptable to
> noise...
>
> Any idea if there is a 5V equivilant, or
> alternatively, Bodgit, any thoughts on using a
> alternative 3.3V + 12V lines for BEEF?
>
> If I understand TTL correctly, 3.3V lines should
> be able to drive 5V TTL, but vice versa is a bit
> riskier? (I.E, driving a 3.3V input at 5V may
> cause issues?) Am I mistaken on this?

I had seen that MCUs have 5 volts input tolerant pins. But they can't output 5 volts. (Need to verify on datasheet)

If almost the industry is now at +3.3V, we should adapt to it. The same happens with that LQFP 0.5mm pitch package, the others alternatives like BGA are even worst for DIY.

And I forgot to say that Opendous provides FreeRTOS for that boards and a ready Makefile, and link for ARM toolchain sources or bin(executable).

Edited 1 time(s). Last edit at 02/18/2010 09:05AM by casainho.

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New cutting edge RepRap electronics, ARM 32 bits @ 100MHz runs RepRap @ 725mm/s:

[www.3dprinting-r2c2.com]

Or just get rid of those, (IMO) stupid, TTL signals anyway.

Beagle's concern has got nothing to do with industry and more praticallity, 3.3v will suffer from more EMI as a percentage than 5v.

> If almost the industry is now at +3.3V, we should
> adapt to it. The same happens with that LQFP 0.5mm
> pitch package, the others alternatives like BGA
> are even worst for DIY.

I don't have any problem using 3.3V, as long as noise can be managed; which means that with a 3.3V system, it becomes more important than ever to keep signal lines short, shielded, and away from noisy power lines.

modern microcontrollers of this calibre frequently don't come in 5v versions, so stick with the atmegas or go 3v3

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-----------------------------------------------
Wooden Mendel
Teacup Firmware

In reply to [dev.forums.reprap.org]

Triffid_Hunter Wrote:
-------------------------------------------------------
> modern microcontrollers of this calibre frequently
> don't come in 5v versions, so stick with the
> atmegas or go 3v3

Disadvantages of ATmegas when compared to ARM Cortex M0 and M3:
- very expensive if compared with a ARM Cortex with USB, at 100MHz and 256Kbytes flash;
- no Open Source debugger hardware (which is a must on a complex system as RepRap, and even more complex in future);

Advantges:
- package;
- 5V;
- Arduino libraries;

If someone have more to add, please do.

---

---
New cutting edge RepRap electronics, ARM 32 bits @ 100MHz runs RepRap @ 725mm/s:

[www.3dprinting-r2c2.com]

The obvious disadvantage is 8 bit compared to 32 bit and slower clock. Also AVRs are single source but every manufacturer, including ATMEL now make ARM products.

I don't think 5V is much of a problem. The only part of reprap that needs 5V is the opto endstops and a simple pull down would sort that out. Some ARMs have 5V tolerant inputs anyway.

If the Arduino libraries are any good they should port easily. Not that I think any libraries are needed for RepRap.

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[www.hydraraptor.blogspot.com]

On 3.x volts.

Providing your drivers are up for the current, you can drive a 5v input from a 3.x volt output. The 5v input should see this as logic high when it is not low.

The other way around (5v to 3.xv) you realy have two options.

1. Use a level translator (higher current and higher speeds, where these matter)
2. Use a voltage divider. (bottom of network to ground, middle of network to 3.xv input, top of divider to 5v signal.

2 is slower as it introduces resistance that can combine with stray capacitances to make square wave edges less crisp, but is cheap. You see this technique often as a way to interface SD cards to 5v Controlers. Best avoided if you are driving longer traces and cables.

The BEEF back plane is passive so will be comfortable being run at 3.xvolts if you wish on the digital IO. All cards that will use the signaling though need to be compatible.

On power supply, to use 3.xv and maintain some degree of compatibility with other cards (even if only as an interim solution because you are redesigning all the cards to go 3v) use oncard regulators to drop the 5v from the backplane Power rail to 3.xv.

You could feasibly run the backplane 5v supply at 3.xv but all your cards would then need to match. Diverging too far from the spec makes it less likely that you will be able to mix and match cards from differing suppliers.

Personally I will be sticking with 5v (for all signaling), for a while. (even if I may occasionally have to use 3.xv on plugin cards).


Ultimately though the choices as for the machinery and electronics are yours.

aka47

PS nice ARM's, I like the M3 have a go at a piggy back board for it, The pin break out should make it easy. Have a look at the Antipasto folk and the Aardvark arduino alike IDE for use with ARM controlers.

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Necessity hopefully becomes the absentee parent of successfully invented children.

It looks like makerbot might be playing with the TS-7500

[www.embeddedarm.com]

I found this by looking through there subversion files.

Also I have been working on porting over the Sanguino to the Arduino footprint and also the parts that are on the mother board and extruder board on to shields.

I don't know if this will be of any benefit but it might make things a little cheaper if somebody has an Arduino also it will make thing easier to upgrade from the Sanguino to the Arduino Mega for example.


Bruce Wattendorf

aka47 Wrote:
-------------------------------------------------------
> On 3.x volts.
>
> The BEEF back plane is passive so will be
> comfortable being run at 3.xvolts if you wish on
> the digital IO. All cards that will use the
> signaling though need to be compatible.

Cool.

Since I suspect 3v logic and 5v logic will both be fairly common, I propose that all cards to be used on a BEEF state explicitly the supply voltage requirement and IO expectations:

"Gadget BEEF:3v3"
"Widget BEEF:5v"

Unless otherwise stated, it would be assumed that you only use voltage compatible cards. Exceptions to be state along the lines of:

"Gadget+ BEEF:3v3 (5v tolerant)"
"Widget+ BEEF:5v (3v3 tolerant)"

where 'tolerant' means it uses the 12v line + power regulator for VCC, and will accept digital IO signals with the wrong voltages.

A card that can work with whatever voltage and digital exist (It runs as happily at 3v3 voltage as with 5v) could be labeled along the lines of:

"SuperGadget BEEF:any"


Someone might also always create an adaptor + IO buffers to chain separate BEEF backplanes with different voltage requirements together:

"GlueBEEF BEEF:3v3 + BEEF:5v"

Yup, that looks sensible to me.

---

Necessity hopefully becomes the absentee parent of successfully invented children.

Just Thought re :-

>"Gadget+ BEEF:3v3 (5v tolerant)"
>"Widget+ BEEF:5v (3v3 tolerant)"
>
>where 'tolerant' means it uses the 12v line + power regulator for VCC, and will >accept digital IO signals with the wrong voltages.

For me personally.....

It is better to be the 5v line rather than the 12v line. Purely because 5v then needs no regulator (Cheaper), and a 5v to 3.xv regulator runs a lot cooler and is less wasteful.

12v and 5v supply and how they are derived are issues for a plugin PSU card. Bulk supply of 5v derived from the 12v rail as one regulator on a PSU card is arguably more efficient (Particularly if switch mode) than a lot of regulators dotted on each card (arguably cheaper too).

I have been thinking about PSU cards and of three potential designs (you guys may have some more to discuss)

1. Automotive supply (Car batery and or charger), drives reset from power good detect, protects 12v and regulates 5v.
2. ATX PSU Adapter, supplies both 12 and 5v drives reset from ATX power good.
3. Humanitarian prize compatible, Mains supplied PSU card (12v halogen ET with additional smoothing, and 5v regulation, reset again driven by power good detect)

If someone wants to take a crack at one or more of the above, please do.

Having said all that if as a designer you want to ignore the 5v line altogether, do without a dedicated PSU card and design a PSU from 12v into each card that is your choice.

I guess we are having this discussion and working this out because one size doesn't fit all.

Off to do some more work on the prototyping board/s

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Necessity hopefully becomes the absentee parent of successfully invented children.

aka47 Wrote:

> It is better to be the 5v line rather than the 12v
> line. Purely because 5v then needs no regulator
> (Cheaper), and a 5v to 3.xv regulator runs a lot
> cooler and is less wasteful.

Except if most devices are 3v3, there would be no 5v line. Mixing voltages will be more complicated; maybe it would be simpler to scrap the whole "compatible" idea, and simply require a 3v3 - 5v bridge.

Requirements are likely to leave some folk feeling that this is not for them.

I think that decision is something I would leave to the designers of the cards.

Personally all that I will design are more than likely to be 5v Digital IO. Where I need 3.xv or another voltage because of device specs I will keep this on board, and off the back plane.

I normally avoid 3.xv devices, except in hand held battery powered things or when a "must have" device is only available as 3.xv.

Just because this though is my personal preference it shouldn't stop any one else from doing what they want to do.

So long as (like you suggested earlier) there is some clear indication somewhere that the card uses something other than 5v digital IO on the backplane. Just to avoid accidents when mixing and matching cards.


Thoughts for what they are worth.

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Necessity hopefully becomes the absentee parent of successfully invented children.

OK Guys

THe first of the BEEF prototyping board designs is done and available as a pdf from the RepRap Wiki

[objects.reprap.org]

This is a strip board design.

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Necessity hopefully becomes the absentee parent of successfully invented children.

OK Guys

Tee second of the BEEF prototyping board designs is done and available as a pdf from the RepRap Wiki

[objects.reprap.org]

This is a Matrix board design.

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Necessity hopefully becomes the absentee parent of successfully invented children.

aka47, we're opening up the repository soon. There will be a blog post, then discussion, and some time later Jonathan the head RepRap server guy will make things work.

So, good news is it will happen, bad news is that it might take a few weeks.

Discussion to follow, ideally after the blog announcement.

---

-Sebastien, RepRap.org library gnome.

---

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Sebastien, that is good news.

Thanks for sorting out the nameing etc, that os great.

In the mean time if anyone wants a zip of the Kicad sources so far then PM me your email address and I will email them to you. The zip will be of the tree including the common parts libraries in the root of the tree.

I have come to a brief dead stop on the SM prototyping boards. I am currently agonising over what footprint/s to put on the first boards.

I originally wanted to put an SM footprint on that would let folk experiment with the Allegro stepper driver that is used on the Pololu boards. (I can still do this) but it is'nt a universal foot print ie there are probably not that many devices that will drop straight on and there is cooling to consider. It is a square SM device with a heat pad underneath and is better suited to custom boards than general prototyping. So may be a little break out baord may be best with one of the prototype boards already designed.

Then I thought of the boards Bodgit is working on, the foot print for this device is more standard and a board with this foot print would have wider application, until I checked the current handling spec for the device. Not everyone will want devices that are as low current as this.

So I am currently undecided and want to throw this one open to some input from you guys as to what you actualy want from a dedicated SM prototyping layout??????

In the mean time I will start work on the ATX PSU Board. While we discuss the rest some more here.

Hope this is OK.

---

Necessity hopefully becomes the absentee parent of successfully invented children.

Bruce Wattendorf Wrote:
-------------------------------------------------------
> So here is what I have found so far
>
> NXP LPC1768 $8.70 looks like a very good
> possibility.



Greetings all,

I just found out about a low-cost board with an LPC1768 chip, with the I/O lines broken out to header pins. [shop.ngxtechnologies.com]

The price is right, a bit under $33 US. I ordered a couple, along with a USB/JTAG interface (that supports open OCD.)

It may take them awhile to get here, since the Co. is in India.
Although the product brief mentions USB, that sounds like it's for power only.
The chip itself has both a USB device interface, as well as Ethernet hardware (except for the Phy interface, itself.)


I plan to post to my blog once I get at least an LED blinking.

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Larry Pfeffer,

My blog about building repstrap Cerberus:
[repstrap-cerberus.blogspot.com]