RAMPS for Due!

First I haven't built a 3D printer but I've been researching for weeks. Been following this thread with interest as I just don't want to spend money on an AVR when ARM looks it's starting to take off. Did programming in the past with 8051's and would prefer to not play 8-bit tricks again.

Couple of interesting links to help:
Link to using the 16u2 as EEPROM on the DUE. DUE EEPROM

Really love this blog on the design work for the Replicape ( RepRap interface for a BeagleBone Black)
Hipstercircuits
His work on thermistor ADC noise Noise on the analog pins causes the ADC sampler to go out of whack
Mosfet power control Switching it up

I have to say the BeagleBone Black looks great and can be combine with LinuxCNC. Probably stay closer to Marlin/Ramps till I have the mechanics straight. This looks like a great middle ground once a few people have tweaked on it.

We don’t need a real physical EEPROM, we can fake it in software

see [pansenti.wordpress.com]

The only catch is the eeprom gets over written when you upload a new firmware, but you can back it up with simply saving the results from a m503 command. The 4pi board has this same sort of system. (same results, haven’t looked at details)

Cefiar Wrote:
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> I've got some of Digistumps DigiX's on the way,
> which have EEPROM & Wifi/Mesh on-board.
>
> Freetronics (an Australian company) are getting
> ready to release an EtherDue (Due with Ethernet
> on-board - pretty sure there will be an EEPROM as
> well).
>
> And there's the UDOO and a few other systems that
> combine a Due with a processor. Some have an
> EEPROM, while some don't.
>

I also have DigiX and UDOO in the pipeline somewhere I've read rumours of something like EtherDue on the Due forum, I haven't seen any specifics. I don't know what compromises Arduino team had to make with the Due, but it does seem like they missed some opportunities. However, if it kickstarts an ecosystem of Due compatibles perhaps it doesn't matter.

> Maybe the easiest thing might be to make a tiny
> EEPROM add-on for RAMPS-FD (like the SD card
> adapter that fits RAMPS)? That way, you can add it
> if your board doesn't have an EEPROM.

That is a good thought, I can see a place where I might be able to place an EEPROM, they are quite small. If not, a pluggable EEPROM would be cool.

Is it safe to fab this?
I looks like two layers?
1 ource copper?
board size?
Board FInish?
I was looking for a BOM as well.

glennswest Wrote:
-------------------------------------------------------
> Is it safe to fab this?

I think I would wait a bit to see if there any snafus with Rev A... in particular the power handling capability has not been tested, that could require major changes.

> I looks like two layers?

Yes

> 1 ource copper?

Yes

> board size?

3.95 x 3.5 in or 100 x 89 mm

> Board FInish?

I picked HASL, if that is what you mean.

> I was looking for a BOM as well.

I haven't created a BOM yet....it's a good idea

Since I have to order 10 boards, I will have several spare if anyone wants one.

I'd consider it, but shipping could be non-optimal (me being in Australia).

Assuming itead get the boards back to you by the 18th, there'd still be at least 1 week (more like 2-3) shipping to Aus.

The hackerspace I'm involved with do regular runs of boards (they pack 1-2 off designs all onto one run, so I don't need to get 10+ done), so I might chase that avenue first before asking you to send me a board.

I have just pushed a preliminary BOM to github, [github.com], it needs a bit of tidying still.

I haven't tried getting a total cost, hopefully it should not be too bad. Boards have been made and are on their way!

Now I just need a triple extruder...

FWIW: I've also got some boards coming to me, and hopefully have parts within a week (maybe less).

I've updated the incomplete BOM slightly with a few small things (eg: matching fuses for the fuse holders, general formatting issues, etc). FWIW: F991-ND (10A) and F992-ND (15A).

With LibreOffice 3 (3.5.7.2), I get a filter pulldown on one of the items that seems to cause weirdness when trying to figure out the quantities. It's even worse in Gnumeric. Is this supposed to be there, or can you explain what you were trying to do with it?

I'm tempted to re-jig it a bit and give the user a way to enter in a Qty (of boards) and then it will give a "Qty to order" column. Just makes it easier when you're doing a few boards than manually having to do it later.

Cefiar Wrote:
-------------------------------------------------------
> With LibreOffice 3 (3.5.7.2), I get a filter
> pulldown on one of the items that seems to cause
> weirdness when trying to figure out the
> quantities. It's even worse in Gnumeric. Is this
> supposed to be there, or can you explain what you
> were trying to do with it?

No, there should not be any filters in there, I can't see anything funny in mine. I am mostly using LibreOffice 3.3.2, although the document was initially create with LibreOffice 4. Possibility something crept in as a result of copying/pasting from web browser?

> I'm tempted to re-jig it a bit and give the user a
> way to enter in a Qty (of boards) and then it will
> give a "Qty to order" column. Just makes it easier
> when you're doing a few boards than manually
> having to do it later.

Good idea, I like that.

Edited 1 time(s). Last edit at 10/15/2013 12:53PM by bobc.

Boards are in! That was pretty quick, I sent the order on the 10th, so that's 6 days including 3 days shipping time. I will be busy at the weekend

I found two errors on the BOM, I forgot headers for the Pololus and pins for the Arduino. Rather than specify specific sizes I buy big strips and split them up, they are standard 0.1 types so you may have them already.

item S1012EC-40-ND should be Qty:4
add item 609-3494-ND Qty:1

Great stuff. My boards should arrive early next week. I've already got lots of those 0.1" headers, so should be right, but good call on that.

bob,

how much do you want for a pcb?

---

- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

Hey bob,

First off all, congratulations on your work!
It looks very nice.

I'm interested in one of your boards.
How much for it? Is it just the PCB or have you mounted it completely?
Either way, I would like to try it. I have a delta (Kossel Mini) and using a DUE is a really advantage.
Can you post some pictures of it?

Is it the new revision with the regulator for 24V (as my current setup uses 24V)?

Thanks in advance.

Edited 1 time(s). Last edit at 10/19/2013 06:38PM by llluis.

By the way, Cefiar and bobc,
Where are you guys located?

As I am in Canada, maybe one of you is closer to me than the other (Europe or so).

I was looking the BOM and got a bit confused.
Have you guys ordered from Digikey? Can share the order from there, as I would order from them too.

Thanks again.

I'm in Australia, so postage from here is rather expensive.

I ordered with a bunch of other people from Digikey, but the order is already on the way.

This should work with 24V, as long as you have the 12V regulator installed (which is not required for 12V operation).

That said, I haven't got the bits yet and haven't assembled it, so I can't say for sure it works 100%. bobc may have finished building his.

I'm sure there will be another revision after this (cleanups, small rearranging of components & connectors, etc), but it hopefully should be fine as is. That said, unless you've got a fair bit of electronics under your belt, I'd wait till tests have gone on first. It's possible bobc or myself have missed something. We've both experienced enough we could hack it to work, but it still would be a hack.

akhlut Wrote:
-------------------------------------------------------
> how much do you want for a pcb?

As these are prototype boards and I can't offer a guarantee of workingness, I will send them for the cost of postage*. I am in the UK, and if you want to get shipping estimate there is a price finder at [www.royalmail.com]. Select your location, then "Small packet" , weight 50 grams (per board), Delivery options as required. For example, to Canada it would be £3.50.

*limited offer, 8 boards available!

llluis Wrote:
-------------------------------------------------------
> Hey bob,
>
> First off all, congratulations on your work!
> It looks very nice.

Thanks!

> I'm interested in one of your boards.
> How much for it? Is it just the PCB or have you
> mounted it completely?
> Either way, I would like to try it. I have a delta
> (Kossel Mini) and using a DUE is a really
> advantage.
> Can you post some pictures of it?

Just the PCB. I'll post some pictures as soon as I have assembled one.

> Is it the new revision with the regulator for 24V
> (as my current setup uses 24V)?

It should work with 24V, I have not tested that yet.

As for the BOM, if the Digikey has a part number in it, then order that with the specified quantity. If you copy the quantity and part number columns to a new sheet, copy that to a text file, you can then paste that straight into Digikey and with a bit of luck create an order from it.

There's a couple of minor revisions to the BOM, I will try to post an update soon.

Cefiar Wrote:
-------------------------------------------------------
> I'm in Australia, so postage from here is rather
> expensive.

OK, so I'll get bob's board.
=)

> I ordered with a bunch of other people from
> Digikey, but the order is already on the way.

I mean, can you send me what you ordered from Digikey?
Was it exactly what is in the BOM (apart from the qty)?

> This should work with 24V, as long as you have the
> 12V regulator installed (which is not required for
> 12V operation).

Great.
I will verify the board and install it.

> That said, I haven't got the bits yet and haven't
> assembled it, so I can't say for sure it works
> 100%. bobc may have finished building his.
>
> I'm sure there will be another revision after this
> (cleanups, small rearranging of components &
> connectors, etc), but it hopefully should be fine
> as is. That said, unless you've got a fair bit of
> electronics under your belt, I'd wait till tests
> have gone on first. It's possible bobc or myself
> have missed something. We've both experienced
> enough we could hack it to work, but it still
> would be a hack.

No problem!
I'm experienced with electronics and/or the firmware part and can make it work also.
;-)


bobc Wrote:
> As these are prototype boards and I can't offer a
> guarantee of workingness, I will send them for the
> cost of postage*. I am in the UK, and if you want
> to get shipping estimate there is a price finder
> at [www.royalmail.com]. Select
> your location, then "Small packet" , weight 50
> grams (per board), Delivery options as required.
> For example, to Canada it would be £3.50.
>
> *limited offer, 8 boards available!

Deal. I'll take one.
Will send you my address via PM.


bobc Wrote:
> Just the PCB. I'll post some pictures as soon as I
> have assembled one.

You can send a teaser of just the PCB also.
=)

> It should work with 24V, I have not tested that
> yet.

OK, I'll test it and provide feedback.

> As for the BOM, if the Digikey has a part number
> in it, then order that with the specified
> quantity. If you copy the quantity and part number
> columns to a new sheet, copy that to a text file,
> you can then paste that straight into Digikey and
> with a bit of luck create an order from it.
>
> There's a couple of minor revisions to the BOM, I
> will try to post an update soon.

Great.
In the mean time, I will prepare my Digikey order and wait for your revision.
Are you planning to do it this week?

Here are a couple pics:


RAMPS-FD part assembled by donotdespisethesnake, on Flickr


RAMPS-FD assembled by donotdespisethesnake, on Flickr

I powered up with a Due attached and all seems good so far...

It looks really nice!!!

But I should have paid more attention to those little tiny SMD components which I'll have to solder.
:-(

Nice stuff bobc!

FWIW: Talking to someone who designs a lot of boards - if the 10uF caps we use (currently electrolytic caps) can be replaced by other types, we can reduce their footprint by using the smaller packaged versions, which might give you some more space for stuff.

AFAIK, they're only used for smoothing out the thermistor input, so the ADC doesn't fluctuate much, and I don't believe they really need to be electros, or even polarised.

llluis Wrote:
-------------------------------------------------------
> It looks really nice!!!
>
> But I should have paid more attention to those
> little tiny SMD components which I'll have to
> solder.
> :-(

It has 0805 and SOIC components, which are not difficult with a little practice. I've tried a variety of SMT techniques, but the most effective method I have found is to use a 10X microscope with soldering iron and fine solder. I posted some videos showing my technique on youtube [www.youtube.com].

A microscope is perhaps a pricey option, but IMO well worth it for regular use. I got one off ebay for about $250, similar to this one [www.ebay.com] Certainly some magnification is useful, even if only a magnifying glass on a stand. I think the thing is to find the method best for you, I find the microscope gives me a "traditional" soldering method just at a smaller scale. Some people prefer solder paste and reflow, I didn't find that easier for one-offs.

Cefiar Wrote:
-------------------------------------------------------
> Nice stuff bobc!
>
> FWIW: Talking to someone who designs a lot of
> boards - if the 10uF caps we use (currently
> electrolytic caps) can be replaced by other types,
> we can reduce their footprint by using the smaller
> packaged versions, which might give you some more
> space for stuff.

I admit that was something I just copied from RAMPS 1.4, but I can't think of any reason why a ceramic could not be used.

Please feel free to raise any issues on the guthub, it's a great way to keep track of things.

Will do. Will wait till I get my boards though (on their way now). While pictures do help, having something right there in front of you makes it so much easier to understand/sort through.

Progress so far: I have got homing to work, and tested extrusion OK. Next step: heatbed control!

This weekend I should get it printing, and I will look at getting Repetier firmware going.

What's new?
I see Chinese Due for 15$ on aliexperss [www.aliexpress.com]
Time to buy?

I see absolutely no reason why the 10uF electrolytics on the thermistor circuits shouldn't be changed to ceramics such as Samsung CL21F106ZPFNNNE (Digi-Key 1276-3012-1-ND) 10uF 10V 0805 ceramics.

(Keeping in mind the tradeoffs between physical package size, cost, and voltage rating for high-capacitance multilayer ceramics, 0805 10V is the sweet spot here. The voltage rating is high enough for the thermistor circuit, going to a higher voltage rating will mean higher cost and a larger package. Similarly, you could go down to a 0603 package for 10uF/10V if you really want to, but it's not worth the noticeable cost increase.)

This will save significant space compared to the electrolytics. It also removes the need to specify their orientation during manufacturing, it's one less thing that can potentially go wrong. And they won't explode if somebody is too hamfisted with a reflow oven.

Personally, in terms of maintaining interface compatibility with old LCD boards or SD card boards, I wouldn't worry too much about backwards compatibility. You can't just have backwards compatibility with every crappy old electronics design in the reprap community forever, then you're just locking in crapness. It's OK to step out and say ok, we're breaking compatibility with the old way, but we're doing it properly and establishing a good foundation for defacto community standards for years ahead.

A lot of SD or thermocouple daughterboards for RAMPS that use 3.3V-level thermocouple amp/ADC chipsets such as the MAX31855 have a substantial amount of their component count dedicated to providing 5V-tolerant buffering (say with a 4050) and a 3.3V supply. We don't need any of that with the Due, so I think it's better to simply say ok, here's the SD card or thermocouple or LCD hardware for use with the Due, it's simpler and cheaper, and no, it's not one-size-fits-all backwards compatible.

Maybe it's worth considering having a microSD card slot on the main board, so it's physically close to the Due, to solve cable length issues. The only issue here is that the board needs to be mounted in a chassis such that the card is accessible.

No extra components are needed since you've already got access to 3.3V and SPI at 3.3V levels, just the card socket itself (not expensive) and a 100nF decoupling cap next to it at the 3.3V pin.

Similarly for a thermocouple daughterboard with a MAX31855 (or several) very few external components are needed, so the cost of the expansion board is reduced if you accept that it's a due-only design. You really don't need much of anything except the MAX31855s and a few decoupling caps.

I'm just curious... how much work in firmware changes is needed to make this board work?

I see there are 6x potentially usable stepper channels... so for quickly getting started with access to the 6 stepper drivers, would running Arduino code such as Marlin on the Due and specifying the board type as RUMBA (which is already coded in Marlin and is one of the few with 6x stepper support) and changing the pin assignments if needed work?

Hi Luke! *waves*

The Marlin code unfortunately has a large number of shortcuts and AVR specific optimisations. While the shortcuts won't "stop printing", they do mean you're not getting the power of the Due out of any Marlin port. The AVR optimisations are the real killer, and while I know of one person who seems to be willing (or crazy enough) to tackle converting Marlin (he's going to STM32 though), I don't know of any others.

That said, there are a number of other firmwares out there that apparently do support the Due, and the number is growing. eg:
Repetier
RepRapPro

There are also a number of ARM firmwares that could be modified (mainly adding in Arduino conventions around their already existing C code, since they were usually developed before the 1.5.x IDE was released). The one that has probably the longest dev time behind it (and hopefully the most stable) is smoothieware.

Going from electrolytic to ceramic for the thermistor bypass caps eliminates the cap leakage as an error source on the temp measurement. Maybe not an improvement with a 10 bit AVR ADC, but most of the ARM's I've seen have *much* better ADC's on them. As long as you derate the ceramics >= 60% for voltage they work very well. For a 10V part, that would be 4V. Works fine at 3.3. You can get away with less derating if you move up to something like an X7R dielectric. The:

[www.digikey.com]

is one possible alternative in the same package with an X7R rating. There are a multitude of other choices from other manufacturers.

I just found that Ramps-fd boards are now available fully assembled from [www.geeetech.com]

No idea if they are any good or not... for the price I have ordered one to play with.