Reprap Electronics Devolpment

I've noticed a slight difference between the users that were brought up on the ReplicatorG/Gen3 electronics and those whose first experience was the Arduino Host/Gen 2 electronics. The former have a tendency to treat the firmware as a magical widget that must not be tampered with and the latter tends to see the firmware as yet another hackable element. To be fair, the former seem to be more successful at getting a machine running. There are also many people who break these generalizations.

The problem is that the Gen3 crowd tends to look for solutions that don't involve touching the firmware. I think this is a shame. If RepRap is going to be a success, it is going to be on the shoulders of hundreds of people hacking and experimenting, not a small collection of designers creating a perfect system in one go. I look at embedded systems very warily. If someone is inexperienced it can take a couple hours or more of research to get a development environment set up and working. That is very discouraging, and I think it is hurtful to the progress of RepRap. The Arduino environment has served well at bypassing this cost.

I think a good alternative to the current board is the XDuino because it is being designed as an Arduino clone, with the same very easy to set up development environment. We don't need to use their board to use their software, we can just use the same chip in our own board.

Another approach that might work well is to keep the firmware on a flash card and also put the development environment and source code on that flash card. That way, a new user would copy an image to the flash card and be all set to start making changes to the firmware.

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Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]

rocket_scientist thanks for the specific and constructive input. Exactly what I was looking for. I'd love to see others respond as well.

I'll have to see what mccoyn is up to with his electronics design.

My gut is that something simple and cost-effective is the way to go for the near term to help lower the hurdle of construction/adoption.

Longer term, an approach that would facilitate experimentation but also simple enough for a beginner to use would be great.

In either case, I still think it is important to think about the higher-level objectives first.

TC

I'll note that my biggest disappointment with the board I designed is that it contains over 100 components that need to be soldered. I'd like to find components that integrate multiple pieces into one package. Look at the stepper drivers, for example. The v1.2 board has 8 diodes on it, but the v2.3 board has diodes built into the chip. It would be quite useful to find an LED that could be connected directly to the stepper wires without a current limiting resistor.

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Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]

rocket_scientist Wrote:
-------------------------------------------------------
> TC Wrote:
> --------------------------------------------------
> -----
> > Should we develop an integrated solution or an
> > extensible solution?
> I see three major forks here. 1) Reprap-on-a-Board
> that mccoyn is doing, 2) the current fixed number
> of mostly dumb modular units plugging into a
> single controller board, or 3) a motherboard
> talking over I2C or other shared buss to a
> variable number of smart modular controllers.
> 1) is the absolute cheapest and probably easiest
> to build, especially if commercially fabbed. It
> must have some extra pins and connectors for
> possible future expansion, but is very limited.
> 2) is also very limited, but more expensive
> (multiple small boards instead of single large
> board) but fails to give the full benefit of
> modularity
> 3) Truly extenisible, and interfaces should be
> defined independent of the motor/hardware. So Axis
> drivers should be in millimeters and speeds,
> extruders in orifice size and rate of extrusion,
> heaters in degrees C. That way, when a
> motor-driver combination is changed, the software
> and motherboard do not change.
>
>
> >
> > What does the electronics for a RepRap cost
> when
> > based on MakerBot components?
> Sorry, no idea there. But good point that making
> due with what someone else already makes and sells
> is good. Bad if they are having trouble keeping up
> with demand.
>

$200 on their website for a kit, and about the same in component, I believe Julie (sheep) did a costing exercise for UK suppliers?

> >
> > How much time does it take to build one from
> > scratch for Mendel?
> Experienced solderer, less than a day. But to
> spread the wealth, we need a good source of
> inexpensive pre-built boards. Not everyone can or
> wants to learn to solder surface mount devices,
> and they are the most prevalent and cheapest in
> virtually all parts.
>
>

Depends on the tools used and the experience of the operator

Surface mount is the cheapest, but can sometimes require specialised equipment which is not available to the home user.

With the plate or oven reflow methods listed on the net it is possible for the home user, but requires an expense for a one off.

>
> >
> > How much time does it take to modify pre-built
> > MakerBot components for use in Mendel?
> Don't know here either, but sounds like hours at
> most. Still has the same benefit of re-using parts
> someone else has designed, tested, made. Same
> problem of they might not be making them fast
> enough.
>

Also do not know myself as I have never had to attempt it.

This is one of my personal gripes with the makerbot setup, because of the commercial interest their own product will obviously take precedence.

Hence why I think this effort is worthwhile.

> >
> > How much time does it take to get it all
> connected
> > and working correctly?
> I haven't built one yet, but we suffer from
> identical connectors. Having uniquely indexed
> connectors for each axis, extruder, and heater
> would help with start up wiring, but at added
> cost. Assembled is much different than running. I
> am guess that a great deal of time is taken adjust
> machine parameters, linking tool chains, and
> working out the bugs. A machine calibration
> procedure for basic Mendels would help at least
> with the machine parameter adjusting. Even using
> option 3 above with all interfaces being in metric
> units rather than pulses, you still have to
> calibrate each module for the motor step size,
> gear or pulley ratios, drive thread, etc.
>

Would be an interesting investigation.

>
> >
> > How much expertise is needed to do any of the
> > above?
> As is, both mechanical and embedded software skill
> is needed for assembly and most importantly, for
> adjusting, tweaking, and getting the whole package
> to work. Getting the tool chain to work I am
> guessing take advanced programming skills, too.
> The best solution here is a single design, parts,
> software build. Namely, someone needs to sell a
> flat-pack Mendel kit, with all the parts pre-cut,
> electronics pre-built, tool chain assembled and
> ready to load in Windows, MAC OS, and Linux. Then
> the bar of skill level needed to reach first parts
> will be much lower. But now that is do more to
> commonality of packaging than build design. We
> currently do not have a valid build design that
> makes it supper easy to go from zero to printing
> parts in any machine or electronics design.
>

One of the concepts I want to try and introduce with the new software is a configuration system run from the interface tool, this should help eliminate the need for users to have to hack the code to setup the basic system.

The code would be shared and open source etc so users wishing to make changes can do, but this situation doesn't force the user to have to hack code.

> >
> > What is the likelyhood of a succesful outcome?
> For people who post on this forum, I would guess
> 50-90%. For their friends, 10-30%. Once again,
> guessing, shooting from the hip.
>
> >
> > What is lacking in these approaches
> > (documentation, availability, whatever...)?
> Single, uniform design, parts, package, and
> documentation on how to assemble, calibrate, test,
> and make your first custom parts. The electronics
> design choice made has less to do with this then
> having a single, common package for many
> newcommers.

Fair point

> >
> > Is it more important to have a pre-built ready
> to
> > use board, or a board that the end-user can
> > assemble themselves from components?
> Pre-built is the only way to lower the bar of
> possible builders, and make these more wide
> spread. I believe that if you want modularity, use
> a shared bus like I2C, USB, CAN, Ethernet to add
> new extruders, change axis driver motors, switch
> from dead-reckoning with steppers to feedback with
> linear encoders. All this can be made simpler for
> the less geeky user if the new hardware comes with
> all the driver electronics attached and
> precalibrated for a standard configuration.
>

Unless as above, you have the pre-compiled binary and a configuration system, the thing is many people are modifying the mendel design aswell and so there needs to be some flexibility in the software to support this.

Having the capability for cheap off the shelf self build, self assembly kits and built solutions are all necessary with varying costs to suit the budget of the user.

> >
> > What other high-level questions should we be
> > asking ourselves?
> What new features do we hope to need processing
> power, I/O pins, connectors, controllers, drivers
> for?
>
> A) More than one extruder
> B ) Extruder head, milling head, other head
> exchanging hardware
> C) Extruders with more than one opening size,
> speed of extrusion.
> D) Step counting, or rotation counting of gears
> pulleys with optical or magentic encoders,
> feedback from linear optical encoders, ultrasonic
> or Infrared ranging feed back
> E) built in 3D scanning camera(s) and lights
> F) Heated bed, possibly zone heated bed
> G) Mass storage of
> H) User interface independent of controlling
> computer
> I) User controls?
> J) additional axes for milling heads or other
> specialty heads
> K) ability to clear or advance the work space/bed
> to automatically make room for next piece to be
> made.

I agree there are many desirable features for the system, but at the same time many of these were intended to be introduced to the current system with little success at this time.

When starting with a clean sheet of paper, it is best to focus on the core requirements, while considering the future desires so as not to compromise their introduction at some later point.

> >
> > TC
>
>
> My final advice is that if you want to make
> modular electronics, each satellite boards should
> not only be wedded to their hardware, but they
> should include their own small micro with onboard
> constants to completely isolate the motherboard
> (and main software) from all the hardware details
> and take only standardized interface instructions.
> Anything less is simply splitting the main board
> up into more expensive parts.
>
> To soften that last statement a little, running
> motors, stepper motors, solenoids, and heaters
> requires lots of power, and that means waste heat.
> Spreading the motor controllers around on modular
> boards helps with the cooling. Unless you are
> using something like nophead's IC cooling fan
> mounted on top of quad Polulu stepper drivers, in
> which case keeping the heat generating parts close
> together allows for one main cooling design.
>
> Mike

I agree a modular flexible design is desirable, I have also considered using multiple controllers for the architecture and believe it could be a beneficial solution.

However there is a lot of time and money required develop such a system, with potential unknowns which may be difficult to address.

I admire people's enthusiasm to want the all singing all dancing system, but lets not try to run before we can walk.

sheep Wrote:
-------------------------------------------------------
> I think there is a lot of underestimating the
> software costs. This is usually described in
> units-per-free-time-interval. Or in Tecklish
> UPFTI. Many call this wasting time.
>
> Some of the ATMEL workshops I attended did AVR in
> the morning and ARM in the afternoon. Arm is
> much more a complete solution as the early iPods
> used ARM processors. Are we building printers or
> iPods with touch screens here?
>
> The whole advantage of moving to ARM processors
> --is-- so the home user (poor student) can have
> their C++ and real time Linux kernel and JTAG
> boundary debug. Anything else is just the
> needless complexity of ego and power. Or a
> veiled attempt to sell controller boards.
>
> Linux has probably been around at least 15 years.
> I remember it as old and stable in the 1997
> time-frame. Given the number of folk using Linux
> this probably reduces to a billion or so years of
> UPFTI. At least some hundreds of millions of
> years.
>
> While things like FREE RTOS are nifty and neat,
> these do not simplify things for the home user and
> put cash in pocket. The home user does want a
> one size fit's all approach. This is why most
> people purchase a laptop of PDA.
>
> I still think the 2 ton canary in the room is the
> software/firmware development time. In practice
> the time it takes to modify download and get the
> machine running.
>

Hence my suggestion of a configurable system, no need for a user to do this, if someone wants to hack and/or modify a system it's upto them

> Now I am no fan of Arduino. Mostly because I
> learned something else first. Invested time in
> writing an embedded micro-kernel for AVR. I may
> be the odd person out here as I tend to program in
> assembly with my own micro-kernel. Something
> that has evolved over ten years time.
>

One of the reasons I'm not pushing for everything at once, get the core operations running on a simple system and evolve that system to add the new features.

I can and have used assembler, one of the benefits of the cortex architecture is that it lends itself well to C, if you think C is going to create problems for users then have fun explaining assembly language.

>
> Why do people like C++/Java? My observation has
> been that there is a lot of code base that can be
> re-used. This saves time. Need a library
> function to add two floating point numbers?
> Someone in the last 30 years has written such a
> thing. No real time needs to be spent. Download
> and done.
>

I understand C++/Java have benefits, and yes code reuse should be used where possible, but this can be done in C and other languages as you covered above. It doesn't have to be object orientated language to do object orientated design.

Floating point is a whole other argument.

> Even though software patents exist. Due to the
> nature of the way software was given away in the
> 1950s through 1970s, most people feel that a few
> lines of code is free and can not be protected.
> There is no way to prove where those bits came
> from.
>

Software patents only exist in the US

> Users expect free code solutions which do not
> amount to a lot of extra time wasted. Why things
> are hard, because one is aware the they are going
> to waste time.
>
>
> These groups seem to be spinning over and over the
> same thing the last three months or so. It more
> and more seems to come down to the same old "Not
> invented here attitude." which seems to
> predominate culture. Ironically the printer will
> allow us to keep the design imagery of our culture
> intact, or go back to an aesthetically more
> pleasing one
>
> So what can we propose or do, that will put more
> cash in the users pocket? Cheaper ARM hardware
> may amount to more expensive software if C++/Linux
> is not used. The bar gets set higher less people
> are able to contribute. The problem more complex.
>

I think linux is overly complex for the task that we are trying to assign it, in other words, a lot of the functionality will be redundant and/or wasted.

Which could potentially detrimentally affect the performance of the system.

>
>
> I still think the core requirement it to move
> motors, sense temperature and set heaters. Same
> as an HVAC system. This is precisely the areas
> ATMEL AVR works best. Smart thermostats and
> sprinkler controllers
>
>
> At the moment the more affordable AVR hardware has
> some supply issues. On the other hand, home
> builders can use this and make the boards simply.
> Or even on solder-less breadboards. The program
> tools for this are cheap at the cost of a nice
> dinner for two in the San Francisco bay area.
>

Yes they are not expensive, but they are a cost for a one off task.

I personally would put food higher up the priorities list.

> What is the current bottleneck? My guess it is the
> communications between boards and the different
> parts of the printer. This combined with the
> setup needs for the step rate, drive type and
> extruded width. The remaining is limit fail-safe
> conditions. The end stops and temperature sensors.
>
>
> The first of these is USB host side. Simply
> solved with an FDTI chip. physical cost but no
> UPFTI cost. The user is not aware of any time to
> program the interface. Data arrives when needed.
> Granted USB is a bit awkward on AVR.
>
> Next issue is stepper communications. Ideally
> lots of pins. This makes it easy to do delay
> loop waits and single thread programs. Some form
> of interrupts can be used for the limit fail safe
> conditions.
>
> Given a RTOS do most users even know how to code
> multi thread. Semaphores, message queues and
> mailboxes? Artist look at this and freak out as
> they have been told this is advanced work. Even
> though they use the same time slicing to paint a
> still life of an bowl of fruit.
>

I am not aiming to produce an entire development system, but a solution to the Mendel electronics system

> Am I to understand that a $13 board will uncork
> this bottleneck and make board to board
> communications magically happen? That JTAG
> boundary scan with out a bed of nails will
> automatically debug the firmware fixing this with
> additional calls to malloc and free?
>

No of course it doesn't, but I am proposing a repairable single board (other than end stops) cost reduced solution that could run a mendel.

> Most users just want to print something.
> Preferably something that will put cash or food in
> pocket. This is why there are suppliers like
> makerbot and sparkfun. One of the things that
> attracted me to the project was the simple
> distributed electronics.
>

All the distribution of the current architecture offers is the capability to replace damaged SMT components. Which is difficult do for experienced technicians with the correct tooling.

> I still think that an EMC2 solution would be
> better than the ARM solution. Or else port the
> EMC2 kernel to ARM. Anything to let the users
> continue to develop in C++/Java. That is the
> base line. Anything else is just claiming
> territory for a new single sourced empire.
>
> -julie

There are a couple of limitations of EMC2:

1. Its linux only, ok its free, but a lot of work for the user and very dependant on their computer literacy.

2. It requires a parallel port which most PC's of the last 5 years don't have, and 99% of laptops definitely don't have.


-Andy

FYI to all in this forum
I am days away from starting a kickstarter.com proposal for Reprap electronics.

With the goal of starting a web store for selling Reprap electronics and also selling and supporting development of any new electronics..

I will post when the bidding on kickstarter is open.
our web site is going to be rep-up.com and right now points to the kickstarter site which the link is broken last I checked.


Bruce Wattendorf

mccoyn Wrote:
-------------------------------------------------------
> I'll note that my biggest disappointment with the
> board I designed is that it contains over 100
> components that need to be soldered. I'd like to
> find components that integrate multiple pieces
> into one package. Look at the stepper drivers,
> for example. The v1.2 board has 8 diodes on it,
> but the v2.3 board has diodes built into the chip.
> It would be quite useful to find an LED that
> could be connected directly to the stepper wires
> without a current limiting resistor.


Led with current resistor

Quote
annodomini2
> Hence my suggestion of a configurable system, no
> need for a user to do this, if someone wants to
> hack and/or modify a system it's upto them
>

How do you propose this? Inch vs metric. How to set the diameter of the extrusion? Where are the home and clean tool [toolchange] positions?

Does the user download setup files. Or are there switches, which are either rotary or little ones that are hard to see? Some people like make files, others like hidden resource files that are interpreted.

If you do not see it does it exist?

Quote

>
> I can and have used assembler, one of the benefits
> of the cortex architecture is that it lends itself
> well to C, if you think C is going to create
> problems for users then have fun explaining
> assembly language.
>

Happy accident, I have been programing Assembly for 35 or so years (8080/6502 & IBM 370) For the last 10 I have been programming AVR.

I am not suggesting that you or others do it this way. It is what I have on hand. I may have 50 or so AVR processors of different grades, left over from other projects. For some reason, the processor needed is never the one at hand.

I have nothing against C. Prefer it myself. The question here is of perception. I know a number of people who can write scripts in Perl or Basic. Mention C and they freeze solid. Yet these people are quick to jump on the Ruby or Python bandwagon. Not sure why this is?

The reason that I bring up assembly is that I am reporting and sharing what I know. Pointing out, that for me I have 10 years of experience on something.

Quote

> I understand C++/Java have benefits, and yes code
> reuse should be used where possible, but this can
> be done in C and other languages as you covered
> above. It doesn't have to be object orientated
> language to do object orientated design.
>
> Floating point is a whole other argument.
>

The computer illiterate and those learning are much less put off by object oriented code. It really is not that different than connecting LEGO blocks.

What code is re used, should not be confused with how the code is re-used.

It seems to be a rule of nature, that there are producers and consumers. That for every producer there are many consumers. Ideally the relationship becomes symbiotic, where there is balance.

Quote

>
> I think linux is overly complex for the task that
> we are trying to assign it, in other words, a lot
> of the functionality will be redundant and/or
> wasted.
>
> Which could potentially detrimentally affect the
> performance of the system.
>

Linux is as Linux does. One does not have to be computer literate to use it. It is the least scary option for the novice beginner. Completely open and as powerful as needed.

I worked for apple or apple sales or contractors for the first 20 years of my working carrier. This really is the least scary system. Although at a high price.

On reprap project apple does not work well due to the research nature and low entry cost desired. In practice the underlying system still is UNIX even on apple. The only reason apple went with BSD over Linux was due to the nature of the software license.

There seems to be a feeling that reprap is a product. That the product is a turn key solution. There is also a strong sense of entitlement that the cost should be low or shared.

Actually I was quite fond of Johnson & others who created the industrial complex. I still love browsing through surplus stores. Every item on the shelf was someone's dream of profit.



> I am not aiming to produce an entire development
> system, but a solution to the Mendel electronics
> system
>

We already have a working Mendel solution. Somewhat sourced by makerbot. There is no reason that someone else can not make the boards. The designs are easy to download. If one really wants to the boards can be etched at home. Bit more work that way with the vias,

I will admit there are supply issues. These seem to be created by the demand. That more than anything should indicate this is a working and valid solution.

Reprap is not HP or a company that sells turnkey boxes. It is a research project.

Quote

>
> No of course it doesn't, but I am proposing a
> repairable single board (other than end stops)
> cost reduced solution that could run a mendel.

Reparable or repstrapable? Not quite sure why reparable? Again we are not designing a turn key product for HP or Dell. Sometimes I am not quite sure what we are doing? Personally I would feel bored sitting on a white sandy beach drinking from cocktails that have little umbrellas in them.

I personally like wasting my time on the 300 or so projects that currently interest me. I even complete one from time to time.




> All the distribution of the current architecture
> offers is the capability to replace damaged SMT
> components. Which is difficult do for experienced
> technicians with the correct tooling.
>
>

I use a $35USD heat gun from a local home improvement store. This combined with a K thermocouple which the project needs anyway, I can slowly heat the board to 210C holding at 150C for a minute or so.

Many centuries ago, A school I attended decided to save costs on some needed glass teletypes. [Dumb computer terminals.] This was in the golden age of building from kits. The best of these kit makers was called heathkit. It was a cost effective way to make a color television, although most of the kits were aimed at the amateur radio market.

So the smartest engineering students were selected. The ones expected to actually go into the world and create the buildings and bridges we use.

I was the TA in this class. One student managed to have no less than 6 columns of smoke emitting from the kit on first power testing. The repair department was amazed that someone could be so careless and incompetent. The board was replaced and the burned board nailed to the wall of the TV repair shop that provides support for botched kits.

Ironically Heathkit sourced some of the television parts from Zenith. Zenith saw this as a leg up to compete against Apple. Radioshack, Commodore & other forgotten companies that sold computers. Zenith bought Heathkit & sold the kit computers as turnkey systems. IBM then entered the market & somehow Zenith became a wholly owned subsidy of Asia inc. The kits were discontinued, Since the easy build manuals were copyright, these were no longer sold to young people getting started in life.

Now no one build kits.

Quote

>
> There are a couple of limitations of EMC2:
>
> 1. Its linux only, ok its free, but a lot of work
> for the user and very dependant on their computer
> literacy.
>

Not really. Linux is the least scary option for the new user. A decade worth of development. I doubt there is a person under 25 who is afraid of Linux. This is because it is just so warm and fuzzy like a penguin.

Quote

> 2. It requires a parallel port which most PC's of
> the last 5 years don't have, and 99% of laptops
> definitely don't have.
>

>

My suggestion is to run EMC2 with the Linux real time kernel on the smallest ARM development kit possible (I think this is ARM7.) This way one does away with the parallel port. Users can telnet in through Ethernet for setup. To them it would be a web page. Code and data would be stored on a SD (SDHC) card. USB could be used for keyboard control. The demos I saw of this at the ATMEL workshop a few years back, The output feedback could be on a small LCD screen [1/4 VGA]

-julie

annodomini2 Wrote:
-------------------------------------------------------
> rocket_scientist Wrote:

> > A) More than one extruder
> > B ) Extruder head, milling head, other head
> > exchanging hardware
> > C) Extruders with more than one opening size,
> > speed of extrusion.
> > D) Step counting, or rotation counting of gears
> > pulleys with optical or magentic encoders,
> > feedback from linear optical encoders,
> ultrasonic
> > or Infrared ranging feed back
> > E) built in 3D scanning camera(s) and lights
> > F) Heated bed, possibly zone heated bed
> > G) Mass storage of
> > H) User interface independent of controlling
> > computer
> > I) User controls?
> > J) additional axes for milling heads or other
> > specialty heads
> > K) ability to clear or advance the work
> space/bed
> > to automatically make room for next piece to be
> > made.
>
> I agree there are many desirable features for the
> system, but at the same time many of these were
> intended to be introduced to the current system
> with little success at this time.
>
> When starting with a clean sheet of paper, it is
> best to focus on the core requirements, while
> considering the future desires so as not to
> compromise their introduction at some later
> point.
>

annodomini2

I agree that we have a long way to go to implement all these wish list items. I present them not to imply that any new board or firmware must have all of them working, but more to say 'leave enough code room, I/O ports, expansion buss connections to grow into this'. I find when doing a blank sheet design that I want to leave room for growth, but more specifically to put hooks into the system to attach later expected enhancements. To provide access to variables that are not important now, but will be when I add --blank-- later.

We are very specifically working with minimalist hardware, both to keep the cost and the complexity down. If we do not plan for future growth, we quickly reach the physical limits of our design. At some point, there is a cost/complexity trade off for building a controller board big enough and complex enough to handle everything foreseeable. That is what we, or at least I, am thrashing around right here. But i prefer to have a list of all the extras to make sure I don't simply forget one that could have been provided for cheaply. And also to more accurately balance the scale of core simplicity vs growth complexity.

If we stay with an 8 bit microcontroller like the ATMega (which I like by the way), we will pretty much have to right off ideas E, H, an I. If we build a system without an internal expansion bus, the built in 3D scanning will never occur, no matter how powerful the processor. If we don't decide on some form of future user interface, like an LCD panel, and include a port for it, then even with all the mass storage and processing power, we will have trouble adding a user interface.

Basically what I am saying is, if it doesn't jack up the price and complexity too much, lets define interfaces for how we guess we would like to do these things, and design connections on the motherboard to allow them. If they connections require too much delta over a core design, then I agree, we put them off till a later generation motherboard. But I think we can add expansion ports, connectors, and buses for most of this with making it too much more expansive, and then we can get a LOT of mileage out of this generation hardware/firmware design before we have to scrap it for something that can handle the newest gee-wizzes.

So basically, I am recommending we advance to an ARM based motherboard (even with the trouble of it being surface mount only), have at least 3 extruder connectors, at least 4 axis connectors, a guess at a milling head connector, 2 limit switches for each axis plus 2 or 3 more for sensing the exact X,Y,Z location of the working head, bit, extruder, a multi-zone heater controller interface, a USB or Ethernet bus connection, an I2C expansion bus connection, at least 4 quadrature encoder connections, some guess at a laser scanner and CCD camera input for 3D scanning connection, and some kind of LCD and buttons or touch screen interface. I think multi-zone heated bed controller interface, the CCD camera interface, and the LCD and input device can all work ont he same I2C bus, so it is not quite as bad as it sounds

A second suggestion is to put all the extra connectors, a secondary processor, expanded memory and other things that don't work yet on one half of the board, and all the 'we can do this right now' stuff on the other half. That way we can build half boards that have lots of traces that go to the edge and vanish, but use the same hardware, firmware, layout etc when we expand by completing the other half of the board. And builders and developers could decide whether they wanted to build a half board, a full board but only half populated, or the full blown expanded system all at once so they could tinker with the extras.

I strongly recommend this approach to reuse a lot of the design and testing effort from this new generation board when we need to expand to add things we are certain we will eventually need.

Should we start a "Half-Board" project?

Mike

---

Team Open Air
Blog Team Open Air
rocket scientists think LIGHTYEARS outside the box!

I remember Heathkit foundly. My father built a color TV back when there we very few of them around. I built a few kits myself. Now the only electronic 'kits' are the ones in the high tech section of the toy store.

Mike

Quote
sheep
Many centuries ago, A school I attended decided to save costs on some needed glass teletypes. [Dumb computer terminals.] This was in the golden age of building from kits. The best of these kit makers was called heathkit. It was a cost effective way to make a color television, although most of the kits were aimed at the amateur radio market.

So the smartest engineering students were selected. The ones expected to actually go into the world and create the buildings and bridges we use.

I was the TA in this class. One student managed to have no less than 6 columns of smoke emitting from the kit on first power testing. The repair department was amazed that someone could be so careless and incompetent. The board was replaced and the burned board nailed to the wall of the TV repair shop that provides support for botched kits.

Ironically Heathkit sourced some of the television parts from Zenith. Zenith saw this as a leg up to compete against Apple. Radioshack, Commodore & other forgotten companies that sold computers. Zenith bought Heathkit & sold the kit computers as turnkey systems. IBM then entered the market & somehow Zenith became a wholly owned subsidy of Asia inc. The kits were discontinued, Since the easy build manuals were copyright, these were no longer sold to young people getting started in life.

Now no one build kits.

---

Team Open Air
Blog Team Open Air
rocket scientists think LIGHTYEARS outside the box!

My gut on developing new electronics is to take a three step approach:

1) map the existing solution onto an ARM Cortex M3 microcontroller such as NXP's LCP176x family

2) design and have manufactured an integrated single board RepRap controller

3) develop a extensible/expandable system

My rationale is...

1) Moving to an ARM Cortex M3 overcomes performance and code density issues without adding significant cost or complexity. It has a robust ecosystem of vendors, tools, and experienced users. As a first step I would propose interfacing the existing stepper motor controllers and extruder controller to an off-the-shelf ARM Cortex M3 development board. I'm confident that I can hand-build the electronics that would be necessary to do this. The firmware also would have to be ported. While I feel comfortable doing this also I'd rather have someone working on this in parallel to speed up development. The reason to do this is to demonstrate that it can be done fairly easily, and to set the stage for step 2.

2) Re-design the existing electronics onto a single RepRap Mendel specific PCB. Making a single board is the most cost effective and fool-proof way of getting working Mendel electronics. Having this board manufactured and offered as an assembled, tested and documented PCB would lower the adoption hurdle for the most people. While minor improvements can be made on this iteration major new functions should be deferred to step 3.

3) Take the learnings of the previous step and focus on building a more flexible, modular system. Modular systems are more complex, take longer to develop, and will cost more. However, a modular system should provide much more capable and flexible system to experiment and improve Mendel with.

I'm already working on 1) while also trying to get the parts to build the existing Mendel design.

TC

I must admit to being impressed by the LPC2468

---

Necessity hopefully becomes the absentee parent of successfully invented children.

Quote
TC

2) Re-design the existing electronics onto a single RepRap Mendel specific PCB. Making a single board is the most cost effective and fool-proof way of getting working Mendel electronics. Having this board manufactured and offered as an assembled, tested and documented PCB would lower the adoption hurdle for the most people. While minor improvements can be made on this iteration major new functions should be deferred to step 3.

Seems like a step backwards. Sure this is the settled way to do it. Design a board, then build 100, 1000 or 10,000. From my last 15 months of reading and responding on these forums, this is not what the project is about.

Counter proposal for the near term. Port the existing Eagle designs over to the Express PCB Mini Board. This way new users can have three boards made in a week for about $75USD for the set of 3. Sell the other two if not needed. Endless supply of boards, no one is out of stock.

Might be more expensive at closer to $25.USD for a bare board. This is countered with accesability (at least in the US.) What one gains is the instant gratification. The board arrives in a week. A day to build and one has working reliable and useful electronics. The rest of the parts work out a few US dollars. A given board complete this way should cost no more than 40 to 45USD.

This is the way I prototype. Such a system has worked well in my case these last 10 years. On the other hand I am still tweaking software for such.

That is the problem. Software is infinite, always one more feature can be added. The only thing that creates a boundary is the hardware limitations. At least until someone realizes a Turing machine using an infinitely long quantum string as the tape.

Now if a distributor like Spark-fun wanted to make the controllers, then your suggestion would work. But at what hidden cost?

I have worked for a number of people who's definition of "Factory" is a building where people sit at benches and make products. Take away the people and there is no Factory. Just a bunch of lazy folk who prefer fishing in the local crick.

It always sort of amused me that my high tech designs, were going to be made in a low wage country with some pretty low tech methods of human labor. Even in parts of the US there are such factories. Such depend on a happy satisfied ignorant workforce.

The proposal of "assembled, tested." is only promoting the modern practice of wage slavery. Which is the same form of slavery as what the Romans had 2000 years ago. Even then a slave was paid wages and could buy freedom if they played the ponies correctly. As always castes are involved, and some people really are more equal to others.


Outside the reprap scope of this thread, core to the reprap philosophy is to get away from this pyramid structure. A way of teaching without people knowing they are being taught.

-julie

Julie - I always appreciate feeback, pro or con. That doesn't mean that I always agree with it however. Here are some specific points that I don't agree with you on:

"Seems like a step backwards." I simply don't get your perspective. We'll just have to disagree on this one.

"Counter proposal..." This doesn't make forward progress in my view. I believe that it is important to overcome some of the limitations of the current design by moving to the ARM microcontroller. Simply repackaging the existing electronics doesn't accomplish that goal.

RE: "hidden cost" and "wage slavery"... Hmmm... I'm specifically talking about a fully automated assembly done in a factory here in the US. This means no through hole components. Hand building will require hot-air or hot-plate methods but will still be possible for those that want to do it that way.

I understand that the overall philosophy is to make machines capable of making themselves. However, we aren't going to be there anytime soon for electronics. It seems to me that the next best alternative is make the electronics low cost, reliable, easy to use, and easy to obtain.

To the last point... easy to obtain. There are many ways to get boards like this into distribution cost effectively. I don't see that as being a particularly difficult hurdle. Oh sure, it takes capital investment and lots of work to get something like this off the ground but not so much that it is out of the question.

I'd call it progress by any measure.

TC

TC Wrote:

Quote
TC
-------------------------------------------------------
> Julie - I always appreciate feeback, pro or con.
> That doesn't mean that I always agree with it
> however. Here are some specific points that I
> don't agree with you on:

Not really a problem. I am pretty selfish about opinions. You can not have any of mine.

Note that I am not answering one person. I suspect that there are probably 50 others who read this stuff and are too uncomfortable to post.

Now I am standing on a soapbox in speakers corner of Hyde park. Fine view of the serpentine from here.

"Votes for women!" oops wrong century.

Quote

>
> "Seems like a step backwards." I simply don't get
> your perspective. We'll just have to disagree on
> this one.
>
> "Counter proposal..." This doesn't make forward
> progress in my view. I believe that it is
> important to overcome some of the limitations of
> the current design by moving to the ARM
> microcontroller. Simply repackaging the existing
> electronics doesn't accomplish that goal.
>

The only limitation I am currently aware of is availability. Not that that affects me, I could build 20 Arduinos with the spares I have in stock.

Arm makes sense from a corporate production point of view. Top down supply chain. Totally against the reprap model accessibility.

ARM has potential, but again, the bottleneck is the software -- not the hardware. Down the road this makes it easier for others to get a step up.

Quote

> RE: "hidden cost" and "wage slavery"... Hmmm...
> I'm specifically talking about a fully automated
> assembly done in a factory here in the US. This
> means no through hole components. Hand building
> will require hot-air or hot-plate methods but will
> still be possible for those that want to do it
> that way.

Automated factories do not exist in the US. Might be some in Asia. Ever here of the king of Lud? His followers were called Luddites. Known best for throwing wooden shoes called "sabots" into the machinery.

Politicos still do not like factory automation. Makes people write letters to elected representatives.


Apple tried to make some automated factories. These were for making the Apple ///, Lisa and Macintosh. Probably the //e was made in such. Only took 5 people to run and make early macs. I took a tour of the Lisa factory in Campbell, Silicon Valley. Did not use barcodes. Each item was in boxes and trays of a fixed size. Pick and place robots along with compressed storage. Now the Lisa Factory is a Fry's Electronics retail store.

Problem was that there is not much tax base to be had from a factory that employs 5 people. Too few registered voters. So I think when said factory was shut down there were 500 entitlements working at the plant. Seem to recall that the dirty U word was used in relation to these entitlements. Only time U ever happened in the valley.

Factory tax base was replaced by a GM/Toyota cooperative. GM bailed out last fall, Toyota last week. My mentor told me about this. Asia does use automation. They also employee college graduates and competent workers. Tool breaks, self sufficient worker replaces same.

Here in the good ol U. S. of A. Same automated factory. Since it is automated, we use unskilled labor. Only managers and paper pushers are worth anything. Read Alvin Toffler's "future shock" series. US schools are intended to create Victorian clerks. Our schools system is entierly about filling out forms.

So in NUMI plant. Tool breaks, pull cord shut down line. Take break. Manager fills out form for manager. Middle manager attends meetings. Tool requisitioned from supplier. Calls upper manager on sandy beach drinking from glasses with umbrellas in it. Week later new tool and line operational.

I spent 10 months between 2001 & 2002 working in Kentucky. A real culture shock to this silicon valley girl. The closet word they had for me was hippie. Toured a number of US factories in KY and IN. As we wanted our product made in the US. Was told workers happy to be ignorant and lucky to have such a good job and be taken care of by the kind managers who were looking out for workers interest. Can not say workers were indentured, but radios and newspapers were forbidden.

Loved it when was told that they used the Silicon Valley model with improvements. Said improvements were to do it the way it has always been done.

Did you know that female labor makes for the bulk of factory workers? Myth is we are more precise and can solder those ,5 mm pins. I do fine pitch soldering often & have yet to use hot air for making electronics.

Perhaps we need to make the reprap log pink and put more flowers around here.

Quote

>
> I understand that the overall philosophy is to
> make machines capable of making themselves.
> However, we aren't going to be there anytime soon
> for electronics. It seems to me that the next best
> alternative is make the electronics low cost,
> reliable, easy to use, and easy to obtain.
>

We do agree on something after all. On the other hand nothing we say here will change what will happen. Will entertain a few and possibly make some feel good reading these threads. We are content providers to a society addicted to information overload.

Quote

> To the last point... easy to obtain. There are
> many ways to get boards like this into
> distribution cost effectively. I don't see that as
> being a particularly difficult hurdle. Oh sure, it
> takes capital investment and lots of work to get
> something like this off the ground but not so much
> that it is out of the question.
>

This is why the reprap project is so great. There is no one supplier. Total anarchy, each of us bloggers with our own electronics.

Much can be said for what Makerbot has done. Given those who want a working system fast and have the funds to get one.

No one really seems to understand how capitol investment works. Idea is quite binary. Grow two plants, sell one for twice price of first. This works to about 2^6. After that one is dealing with hundreds of plants. To double investment some sort of game of chance is needed.

In my book capitol should be used to make better product. In practice capitol becomes a game of chance. A game where one buys out competition to stack the odds. Purchace government and all that other intestinal gut stuff. This is really monopolistic. Shakespeare knew what to do, that was over 400 years ago and they are still here. His historicals are pretty funny, but I would not peg the author of Hamlet as a futurist.

Again look at the success of makerbot. What do people here do? They complain because they did not make the bet invest the capitol.

If someone else started producing boards, said boards would be trashed and talked down. This is the "Not invented here" syndrome that so weakens the argument. It becomes about pride. Personal pride, school pride. national pride.

Quote

> I'd call it progress by any measure.
>

Place I used to work had a sign over door. "Change is inevitable Progress is not."




-julie

Quite frankly, I don't get all the political rhetoric and I fail to see how this sort of discussion will help us (or maybe just me) make progress.

TC

aka47 Wrote:
-------------------------------------------------------
> I must admit to being impressed by the LPC2468


the 24xx series is ARM7-TDMI not Cortex M3, the main benefit of the Cortex M series is the introduction of the NVIC or Nested Vectored Interrupt Controller.

This makes it better suited to Real-time control systems.

Agreed. That's a pretty negative outlook on something that's in the early brainstorming stages.

I would be very interested in helping with the development of an ARM based controller. I know there are lots of hard-core electronics designers here, but I too think the hardware shoul be turn-key for most users, so an assembled board is a must.

Let's come up with a simple design that exposes the functionality of the chipset but doesn't necessarily leverage it now. The primary focus should be getting a flexible solution at the lowest possible price.

--Ed

TC Wrote:
-------------------------------------------------------
> My gut on developing new electronics is to take a
> three step approach:
>
> 1) map the existing solution onto an ARM Cortex M3
> microcontroller such as NXP's LCP176x family
>
> 2) design and have manufactured an integrated
> single board RepRap controller
>
> 3) develop a extensible/expandable system
>
> My rationale is...
>
> 1) Moving to an ARM Cortex M3 overcomes
> performance and code density issues without adding
> significant cost or complexity. It has a robust
> ecosystem of vendors, tools, and experienced
> users. As a first step I would propose interfacing
> the existing stepper motor controllers and
> extruder controller to an off-the-shelf ARM Cortex
> M3 development board. I'm confident that I can
> hand-build the electronics that would be necessary
> to do this. The firmware also would have to be
> ported. While I feel comfortable doing this also
> I'd rather have someone working on this in
> parallel to speed up development. The reason to do
> this is to demonstrate that it can be done fairly
> easily, and to set the stage for step 2.
>
> 2) Re-design the existing electronics onto a
> single RepRap Mendel specific PCB. Making a single
> board is the most cost effective and fool-proof
> way of getting working Mendel electronics. Having
> this board manufactured and offered as an
> assembled, tested and documented PCB would lower
> the adoption hurdle for the most people. While
> minor improvements can be made on this iteration
> major new functions should be deferred to step 3.
>
> 3) Take the learnings of the previous step and
> focus on building a more flexible, modular system.
> Modular systems are more complex, take longer to
> develop, and will cost more. However, a modular
> system should provide much more capable and
> flexible system to experiment and improve Mendel
> with.
>
> I'm already working on 1) while also trying to get
> the parts to build the existing Mendel design.
>
> TC

The only change I would suggest is to 1, this is reliant on the developers having access to the boards.

I understand the logic behind this, replace the motherboard and get the software up and running. Not too dramatic a change and backwards compatible with existing systems.

But the parts availability is the limitation and we're hitting the vicious circle again.

Maybe this is my mistrust of not fully understanding the black art that is PCB design.

I would suggest, if possible, that we could develop for the first iteration a veroboard based design that would not require the outlay for the expensive short production run PCBs.

If this is successful it could offer an easily available kit, with investment outlay being the used parts and time, not the additional $50-60 for a one or two off PCB.

The rest I agree with.

I just ordered 10 PCBs that were 100mm x 100mm from Seeed Studio for $40 + $5 shipping. They also have an interesting distribution system targeted at helping open source hardware projects get PCBs. I ordered these boards last week and they shipped out of Hong Kong two days ago.


So, if we have 5 developers we can order a set of 10 for $10 each person and distribute 2 to each developer (having an extra board will encourage testing the limits of the board). Veroboard isn't much cheaper than that.

---

---

Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]

I am very impressed with seeed studio they seem to be as good if not better then
[www.goldphoenixpcb.biz]


Which is where Makerbot and myself order from.

But I did see that they are having a hard time with the open source idea if you look in the seeed studio blog. (it looks like the stocking of boards is an issue.)

Which my goal is to just focus on reprap boards and kits for now and spreading the price I for one don't want to order 10 boards when I only need 1 or 2.
Also I plan on offering kits with different levels of parts like the GRRF is selling.

[shop.grrf.de]



As for going with SMT or not I have been working on a motherboard that will connect into the Arduino mega as a shield and will then work with both the new stepper drivers or the present ones.

My hope would be that the main microcontroler board would fit the Arduino mega footprint then the part that would require the most soldering would be the microcontroler and this would be the part that would be the most popular.
with the hopes that what ever somebody uses ARM AVR.. Arduino it would be able to fit the present electronics. In my eyes this would allow somebody to upgrade, test, develop with out having to replace every board.

I also have been tring to keep the motherboard to a single layer so it to can be made with a pcb router. (which is my main reason for using eagle because the file can be used to cut the board on a router.)

Bruce Wattendorf

Personally I would be using the BEEF experimental platform to prototype processing elements separately from driving elements, then when everything is proven combine all the elements into a single PCB.

Having to have whole bards done again for part problems can be a touch expensive.

Nothing ever works right first time.

Going this route also allows you to divide up the development into separate parts that you know will work together (The interface is already defined) and have separate people/working groups developing concurrently without falling over each other.

Combining the parts together at a later date is actually relatively easy. You will have already defined all the symbols etc to make the part boards. In Kicad all the design files are text files you can cat them together, remove the duplicate bits (sheet and label block etc) then open in Kicad rearrange and label to suit, The relay out a board.

The real hard work having been done with the iterations through design. As you are really just combining into one board something that is proven.

As giants you can stand on each others shoulders.

Decoupling the work groups also works well as it is unlikely that you will actually complete a project where everyone gets bored of waiting for someone else.

---

Necessity hopefully becomes the absentee parent of successfully invented children.

mccoyn Wrote:
-------------------------------------------------------
> I just ordered 10 PCBs that were 100mm x 100mm
> from Seeed Studio for $40 + $5 shipping. They
> also have an interesting distribution system
> targeted at helping open source hardware projects
> get PCBs. I ordered these boards last week and
> they shipped out of Hong Kong two days ago.
>
>
> So, if we have 5 developers we can order a set of
> 10 for $10 each person and distribute 2 to each
> developer (having an extra board will encourage
> testing the limits of the board). Veroboard isn't
> much cheaper than that.

Shipping to the uk is $41

95mm x 127mm vero board is about $2 in the uk plus shipping (~$2), so $4 ok you will probably need a bigger board, but with shipping and divided its a 5 fold difference in price.

A couple of you have expressed interest in collaboration and that's great! We need to connect outside of the forum and I'll try to get in touch with you. You can also try to get in touch with me via the forum's private message capability (assuming it works).

TC

Annodomini2 - For step 1 I am thinking of using an off-the-shelf development board + a hand-built vero board to adapt the ARM microcontroller to the rest of the electronics. I don't think it would be difficult to do this for a small set of boards for development purposes.

I've surveyed many of the LPC176x development boards and even own a few different ones. Once a preliminary plan for the hardware is done then it should be pretty simple to pick the best board for the job (multiple considerations include cost, function, ease of interfacing prototype hardware, etc.).

I've started to investigate the firmware to get a better sense of it. I think this is a necessary step to do a good job of mapping the microcontroller's functions and pins to the required hardware interfaces. I've got a good handle on the LPC176x functions, IO pins, and usage but I'm still learning the details of Mendel.

TC

aka47 - what is the "BEEF experimental platform"?

More generally, I'm wondering what improvements could be made after completion of the proof of concept. So, if you had to make a list of incremental improvements for Mendel electronics what would you put on the list, and what priority would you assign to them?

An example might be stepper motor drivers that can handle XYZ amps without overheating.

What things might be marginal (or broken) and need to be improved (or fixed)?

What things are missing that are needed in the short term (if any)?

In other words, if we do design a new electronics board what incremental improvements could we reasonably make?

TC

BEEF. It's what's for dinner.

---

---

Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]

I've sent messages via the forum's private message feature to people that clearly indicated that they want to collaborate on the development of ARM-based electronics for Mendel.

If you didn't get a message from me and you are interested in this collaboration then please send me a message.

Thanks!

TC

BEEF

I like the idea of having interchangeable boards like that. You could start off with a controller board with an RS232 interface and replace it later with a USB, or upgrade a USB controller to an Ethernet, or one with CF card or SD flash memory storage.

But to make the boards truly interchangeable, I think we need to define the interfaces much more specifically, so that when you replace a single stepper driver module with a dual or a quad, that the same pines will still be used for the same purpose.

I really like the way you have doubled up the power and ground pins, as well as making them symmetric on each end so that is a board is accidentally plugged in backwards, there is not likely to be any damage done.

In the following design suggestions, I am aiming for a 3 extruder system, not the current Mendel/Darwin/Markerbot single extruder. The reason for this is that such a nice, modular design, allowing replacing of older parts with newer, faster, more capable ones should not immediately run out of steam on the very next generation system we are working on, namely a 3 material, one of the conductive. So I feel wee need to allocate backplane pins enough for a 3 extruder system, so that the design can evolve into what we are working on right now.

I like setting a number of analog inputs aside. I would suggest that A0 be 4/5 of the 5 volt supply and A1 4/12ths of the 12 Volt supply so that the supplies can be monitored. The board temperature should be next (probably best to put the temp probe next to the X or Y stepper driver). A2 for the optional heated bed temperature, then A3 through A7 be extruder temperatures, to allow for future growth in the number of extruders. Keeping 4 undefined analog channels for future growth should handle new additions, and frees up a few pins for digital channels.

I we are going to have stepper drivers on the other modules, then we need a minimum of 4 digital lines for each stepper, a digital pulse for each step, step direction (or plus step and negative step. same number of pins either way), negative axis end stop (opto switch or micro switch) and positive axis end stop. For even the current design of only 3 axis of steppers, that is 12 digital I/O lines, out of the 16 allotted. This does not leave much room for any fancy new additions. I recommend moving a few Analog pins and PWM pins into the digital I/O bunch to future upgrades. I would recommend the following:

X Axis Y Axis Z Axis Extruder 1 Extruder 2 Extruder 3
step D0 step D4 step D8 step D12 step D14 step D16
direction D1 direction D5 direction D9 valve D13 valve D15 valve D17
- end stop D2 - end stop D6 - end stop D10
+ end stop D3 + end stop D7 + end stop D11

If we add 4 more digital I/O lines for future use, that means 22 dedicated digital I/O lines. that means taking some from the analog input channels, and some from the PWM channels.

For the PWM channels, we currently know of 1 heater per extruder, and 1 for a heated bed, and possibly one for a cooling fan for the electronics. Possibly one extra fan for cooling of parts after they have been finished to help loosen them from the bed, and possibly a couple of servo motors helping to exchange extruder heads or move things around. If a zone heated bed is used, there will be too many zones to controller directly through the back plane. A sub-processor will be needed that communicates with the main controller through the SPI buss or listen in to the commands sent on the RS485 buss. If we once again put the possibly expanding number of extruders at the end of the list, that is:
PWM0 Heated Bed
PWM1 Electronics cooling fan
PWM2 Parts cooling fan
PWM3 Extruder 1 heater
PWM4 Extruder 2 heater
PWM5 Extruder 3 heater
PWM6 Servo 1/Extruder 4 heater
PWM7 Servo 2/Extruder 5 heater

That leaves only 2 spare PWM channels left for future use. And I think that defines all the general purpose pins.

I would also recommend that we define address in the SPI buss address space. I have not yet successfully communicated from one microcontrollor to another over the SPI buss, but I seem to remember that the standard communication format starts with a 9 bit address, allow 1-127 different devices. If the Axis drivers change from being stepper motors to brushless DC motors or geared DC motors or even linear motors, the change will be too great for the interface defined above. So I would suggest using a sub-processor to handle the new drive format, the varying step rate or PWM signal or coil phase angles to move the axis, and the rotary or linear encoders or other feedback systems added. So I would suggest the following SPI addresses:

0 Main processor (Bus Master)
1 X Axis driver subsystem \
2 Y Axis driver subsystem } may all be on one module card, single processor
3 Z Axis driver subsystem /
4 Theta Axis driver (tilt extruder or milling head)
5 Phi Axis Driver (rotate bed?, move conveyor belt forward?)

10 Bed Heater (multi zone)

20 Extruder 1 driver subsystem
21 Extruder 2 driver subsystem
22 Extruder 3 driver subsystem
23 Extruder 4 driver subsystem
24 Extruder 5 driver subsystem
25 Extruder 6 driver subsystem
26 Extruder 7 driver subsystem
27 Extruder 8 driver subsystem
28 Milling head 1 driver subsystem
29 Milling dead 2 driver subsystem
30 Working head exchanging subsystem
31 Milling bit exchanging subsystem

40 LCD display
41 Operator input

50 Mass storage

60 3D scanning camera(s)
61 3D scanning lights




I am sure that there are more future additions that we can set aside addresses for, but this should do to start the discussion. I will see about pasting this into the BEEF Wiki page, too.


Mike

---

Team Open Air
Blog Team Open Air
rocket scientists think LIGHTYEARS outside the box!

I have purposely avoided defining the pins by anything other than their electrical function.

The usage you use the prototyping platform will be your own spec.

Some methods for driving axes will require entirely different methods. So if we have specified the pin functionality and purpose too rigidly someone wanting to do something different may be excluded.

However if you want to make some boards and designs up using that layout please do.

Hope this helps

---

Necessity hopefully becomes the absentee parent of successfully invented children.