RAMPS 1.4.2 fork: RD3D v1.0 (6 steppers, 24v, Due)

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JustSumGuy
Ok, I am hesitant to post this but WTH...

I have a thought here and its been in my head for a while... seems its a bit along the lines of the design aspects on this thread but as you guys here are WAY WAY past me on design I decided to throw this out there and see it get shot down in flames....
at least if it gets shot down I can get this thought out of my head

The six drivers with three stepsticks for the three extruders..... I cannot think of any time when all three extruder motors are being driven at the same time. Unless you use three separate hotends and I think its still unlikely to drive all three at once.
So would it be possible to use one driver and in some way switch it from motor to motor?
So E1 retracts and parks its filament.. the motor state is stored in variables and E1 is effectively disconnected, E2 is activated and its stored state is pulled and E2 is now actively being driven, while E1 and E3 are just off and waiting their turn...

If this is not just my naive ramblings, then it would save a lot of real estate on the pcb right? Also lower the cost of six stepsticks to the cost of four and still do the same job?

ok, my apologies for being a noob

hey no it's the strange ideas - the ones not limited by what's possible or more to the point what people *think* is possible - that can sometimes turn out to be awesome.

the practicalities of switching the motors basically means multiplexing (re-routing) four wires which are carrying up to 24 volts and possibly up 3 amps total... analog not digital i.e. the motor stepper outputs are supposed to be a sine wave but in reality with s***-quality outputs like the DRV8825 or whatever it is, it's sort-of... badly-shaped noise with a lot of oomph that makes your motors howl like banshees.

anyway, from that description of what needs to be multiplexed, you should have that little thought in your head which begins with the word... "ah." as in.. *pause*... "ah. right." or "ah. hmmm..."

a chip which can handle analog power-routing (faithfully replicating its input as output)... well.... you're looking at either power-transistors or using MOSFETs in a rather unusual (these days) way... as amplifiers. it's possible but not very common. bottom line is: it's really tricky, a lot of work, takes up a lot of board space and probably actually wouldn't save you much in the way of cost.

instead, you could just save yourself some $ by simply... not buying a stepper module if you don't need it. i know i don't actually like these module designs (at all) but the cost is compelling, and the fact that you can use different stepper modules (lower-cost, better quality, whatever) is also very handy.

"So would it be possible to use one driver and in some way switch it from motor to motor?"

This is what the prusa original mk2 and mk3 multi material does.... One driver circuit, 4 stepper motors and their custom pcb

See [forums.reprap.org] for a little more detail..

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Dust
"So would it be possible to use one driver and in some way switch it from motor to motor?"

This is what the prusa original mk2 and mk3 multi material does.... One driver circuit, 4 stepper motors and their custom pcb

See [forums.reprap.org] for a little more detail..

mechanical relays?? *thinks*.... yyeahh... actually that would pass through the current (and voltage) unmodified. ingenious solution... if, as dc42 points out, you don't mind the risk of damage to the motors and also the steppers. which i hadn't considered (you know that recommendation "never plug or unplug a stepper motor when the driver is powered on"?) and would still be present even if you used a solid-state circuit.

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lkcl

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Dust
"So would it be possible to use one driver and in some way switch it from motor to motor?"

This is what the prusa original mk2 and mk3 multi material does.... One driver circuit, 4 stepper motors and their custom pcb

See [forums.reprap.org] for a little more detail..

mechanical relays?? *thinks*.... yyeahh... actually that would pass through the current (and voltage) unmodified. ingenious solution... if, as dc42 points out, you don't mind the risk of damage to the motors and also the steppers. which i hadn't considered (you know that recommendation "never plug or unplug a stepper motor when the driver is powered on"?) and would still be present even if you used a solid-state circuit.

If the stepper was in a disabled state before the switch this should be just fine...... that mux looks about the same size as a step stick.... this would still save the area of an entire stepstick and you could mux four outputs...
I only brought this up because I read a post on how little area there was on the PCB of the design this thread is focused on.
I MUCH prefer stepsticks as I hate the idea of being forced to use whatever driver fit the design on whatever controller I am looking at when it was designed. I love being able to change them to newer ones as things change...
I have TMC2130 on my Ramps setup.... When I am looking at a controller my first thought is what drivers and can I change them.....

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JustSumGuy
If the stepper was in a disabled state before the switch this should be just fine......

mmmm....yyeahhh... firmware screw-up and it's toast

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that mux looks about the same size as a step stick.... this would still save the area of an entire stepstick and you could mux four outputs...
I only brought this up because I read a post on how little area there was on the PCB of the design this thread is focused on.

only because of limitations in eagle. can't stand proprietary monetarily-zero-cost software, but the alternative is KiCAD (which is.. user-hostile to an extreme level) or proprietary software that nobody in their right mind will buy just to make a $7 board.

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I MUCH prefer stepsticks as I hate the idea of being forced to use whatever driver fit the design on whatever controller I am looking at when it was designed. I love being able to change them to newer ones as things change...
I have TMC2130 on my Ramps setup.... When I am looking at a controller my first thought is what drivers and can I change them.....

yehh i know... except absolutely not one single one of these stepper ICs has been designed to work on postage-stamp-sized PCBs. it clearly states, in the app notes or datasheet, that the PCB has to be a certain size, or that the EP (exposed pad) must have a large number of VIAs which join it to large copper areas of the internal and external layers (particularly the external layer on the opposite side) so that the heat can go through and then spread out.

it does NOT say "put a heatsink on top of the plastic packaging which is an INSULATOR and ACTIVELY BLOCKS HEAT REMOVAL"

duUuuuh

if you look closely at the difference between Trinamic polulus (SilentStepStick) and other modules, you notice something very significant: the IC is mounted *upside-down*. that's because the EP (exposed pad) then faces upwards, and it has a huge direct contact area with the copper on the PCB. if you look even closer you'll see there's a staggering array of like... i can't remember if it's 3x3, 3x4 or 4x4 VIAs in that tiny space, which all help bring the heat up. then the heatsink - which is far larger than the ones you normally see on A4988 or DRV8826 stepper modules - is mounted directly onto that area with all the VIAs.

my friend phil had one of the very very first mendel repraps almost 10 years ago now - the one with a sanguolino (huge 48-pin DIL package! hadn't seen one of those since... like... 1980! reminds me of the Z80, the 8080 and the 6502). because there were no linear bearings in that design (just 8mm rods shoved into plastic and you were expected to spray silicon into it *during a print*...) the amount of friction present meant that the steppers were heavily overloaded. they would overheat on a regular basis and one (or more of them) would simply.. stop for a couple of seconds to cool down, then start back up again. no warning, no feedback to the firmware, nothing. he was one of the first people to research putting heatsinks on top of the stepper ICs. it was totally ineffective.

so.... i'm guessing you're using active cooling (fans)? trinamic's steppers are not very efficient (hence the need for more careful thermal design) so, not least because i too want to try the TCM2130s i'd be interested to hear more about how you're running them.

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lkcl

if you look closely at the difference between Trinamic polulus (SilentStepStick) and other modules, you notice something very significant: the IC is mounted *upside-down*. that's because the EP (exposed pad) then faces upwards, and it has a huge direct contact area with the copper on the PCB. if you look even closer you'll see there's a staggering array of like... i can't remember if it's 3x3, 3x4 or 4x4 VIAs in that tiny space, which all help bring the heat up. then the heatsink - which is far larger than the ones you normally see on A4988 or DRV8826 stepper modules - is mounted directly onto that area with all the VIAs.

my friend phil had one of the very very first mendel repraps almost 10 years ago now - the one with a sanguolino (huge 48-pin DIL package! hadn't seen one of those since... like... 1980! reminds me of the Z80, the 8080 and the 6502). because there were no linear bearings in that design (just 8mm rods shoved into plastic and you were expected to spray silicon into it *during a print*...) the amount of friction present meant that the steppers were heavily overloaded. they would overheat on a regular basis and one (or more of them) would simply.. stop for a couple of seconds to cool down, then start back up again. no warning, no feedback to the firmware, nothing. he was one of the first people to research putting heatsinks on top of the stepper ICs. it was totally ineffective.

so.... i'm guessing you're using active cooling (fans)? trinamic's steppers are not very efficient (hence the need for more careful thermal design) so, not least because i too want to try the TCM2130s i'd be interested to hear more about how you're running them.

Ya I think the way the TMC2100 were setup for cooling struck me as more of a way to do it.
As far as cooling I printed this up [www.thingiverse.com] and use an 80mm fan on it. I like this case because it has vents for the air to escape. Too many cases I see have great fan systems to put the air in and blow on the heatsinks but are not thinking about how the air gets back out of said box.... its called airFLOW guys
On the whole I am super happy I upgraded to the TMC drivers. So smooth, quiet, stepper motors are running cooler... Just way way nicer. A little finicky to get the Vref dialed in but now that I am there... really happy and will never look back..... I have a few sets of DRV8825 if your interested lol
Funny you brought up the sanguinolulo, that's what I had b4 ramps.... I was looking at 2130 for like 1$ more per stick but it looked like there was no simple way to use the SPI interface on Ramps so I went with what I was more certain I could make work well with the Ramps 1.4/MEGA setup. When I start looking at 32bit I will likely go to TMC2130. Part of why I looked at this thread in the first place.... Looking at the future I am thinking of a ReARM and a more advanced version of the RAMPS shield for my next build....

Edited 1 time(s). Last edit at 10/03/2017 01:48PM by JustSumGuy.

When you are ready to go 32-bit, you may wish to consider the Duet WiFi or Duet Ethernet. They both have built-in TMC2660 drivers - the big brother of the TMC2130, with higher current capacity. Being built in, they are also cooled better than plug-in drivers, which don't have enough PCB area to provide good cooling.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

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dc42
When you are ready to go 32-bit, you may wish to consider the Duet WiFi or Duet Ethernet. They both have built-in TMC2660 drivers - the big brother of the TMC2130, with higher current capacity. Being built in, they are also cooled better than plug-in drivers, which don't have enough PCB area to provide good cooling.

It is one I have considered, but I like a modular design for repair and upgrade ability. Mostly for repair and hacking, rather replace a stepstick than a whole controller.....
They are very expensive to be tossed when a little smoke appears....
In my opinion All in One designs need to be cheap to enable low cost replacement...

They may be as reliable as stone... I cant get around the way I think of these things tho......

Edited 1 time(s). Last edit at 10/03/2017 06:27PM by JustSumGuy.

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dc42
When you are ready to go 32-bit, you may wish to consider the Duet WiFi or Duet Ethernet. They both have built-in TMC2660 drivers - the big brother of the TMC2130, with higher current capacity. Being built in, they are also cooled better than plug-in drivers, which don't have enough PCB area to provide good cooling.

jsg, dc42 does things properly. no risk of mechanical fan failure destroying boards and ruining prints. the only reason i'm even remotely considering the type of design that RD3D is, is: cost (shenzhen markets). you can't actually get Trinamic ICs in china: they're not made using TSMC's foundries in Taiwan, nor in China, i think they're most likely done at GlobalFoundries or somewhere else in Europe. that means they have to be *imported*. prices for the TMC2660 are NINE dollars U.S. on taobao! even the TMC2100 is around SEVEN. completely mad. even digikey has the TMC2660 at only around $3.50 in 1k volumes [www.digikey.com] and the TMC2130 is $2.50 in 2k volumes.

btw dc42, am i right in thinking - i seem to recall this from the schematics: you've got full SPI connectivity to the TMC2660s on the DuetNG designs, right? that would mean it would be possible to do SPI-driving of the steppers. have you seen the TRAMS Reference Design? they actually did a port of Marlin firmware to properly use the TMC5130's SPI interface even for the endstops, really neat... except they screwed up the MOSFET design part of the layout (got an instant burn-out) i don't think they actually properly checked 24v, whoops.

the one thing i would really really like to help with, when i get to it and have the hardware to experiment, will be adding support for SPI stepper driving rather than having to always do PWM control.

2017-10-04 Wednesday
05:21:21	Shipment loaded at 【Taiwan Taoyuan Distribution Centre】, 
                 send to 【Taiwan New Taipei Xindian Marshal Industrial Park Distribution Center】
01:43:15	Shipment arrive at 【Taiwan Taoyuan Distribution Centre】

components and PCB will either be going through customs (and be delayed) or it *might* be on its way to me today, and be here some time in the afternoon. we'll see!

Edited 1 time(s). Last edit at 10/03/2017 06:33PM by lkcl.

@IKCL

Do you have one of these RD3D v1.0 controllers up and running? or know of anyone that has done one?

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JustSumGuy
@IKCL

Do you have one of these RD3D v1.0 controllers up and running? or know of anyone that has done one?

my friend who runs a factory north of shenzhen just managed to get me the components and the first-revision (pre-1.0) bare PCBs out before the big holiday in china: that's what the messages from shunfeng express are about the actual design's only about... 10 days old (beginning date of this thread), i work quite quck, and completely publicly, so that people can help catch mistakes, give really good advice and so on.

the first prototype won't have SPI to the steppers, btw - that'll be on the 2nd prototype. i don't want to send that one off until i've assembled and at least started the RepRapFirmware port (still haven't managed to get in touch with chrishamm by email... anyone got contact details for him? no i do not use github - i'm a software libre developer and advocate). SZ Maker Faire is 10-12 nov, that's what i'm aiming for: the first prototype if i get it to work i at least have a backup, and if the 2nd also works before then *great*.

so that's some timescales for you, only possible because this is a 2-layer board and the components are really really common.

my god it's full of... holes! [www.youtube.com] you can actually see the doorframe through it. dang.



ok so components, really quite basic. i'm going to try first to run this on an ATMEGA2560, not the Due - i'll see how Marlin fares with it. i'll have to cut the 5V track which is accidentally connected to 3V3 up in the top-right near the I2C lines (whoops...), maybe skip the buffer IC on the first one (use jumper wires), cut the 3V3 and wire it to 5V instead...

reason is: i noticed already that there's overlap between the quad-buffer and the MOSFET outputs, whoops - don't have that problem on the latest revision but still going to have to watch that. the (large) 15A connectors sit just outside of their marked area, oops...

the MOSFETs - ESD-sensitive as they are - arrived in a zip-loc plastic bag... *sigh*.... welcome to china luckily i have lots of them.

ok! so we'll see how this gets on, later.

If they needed the link for the reference... they are just babies

Sadly static sensitive devices in zip-loc plastic bag is common....

I once got a micro controller sellotaped to a bit of cardboard in glad-rap... never bothered even trying it.

Board looks good. Looking into my crystal ball I see soldering in your future

BTW have you seen the new Einsy-Rambo? still 8 bit, but its a 6 layer board (so im told) Trinamic2130 drivers, with spi so can do all the fancy stuff.

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lkcl
btw dc42, am i right in thinking - i seem to recall this from the schematics: you've got full SPI connectivity to the TMC2660s on the DuetNG designs, right?

Yes.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Looks like fun times ahead, simple as I am, I rather enjoy a good soldering project.

Ever do much SMT by hand? That's where it really gets interesting.

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obelisk79
Looks like fun times ahead, simple as I am, I rather enjoy a good soldering project.

yehyeh, me too.

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Ever do much SMT by hand? That's where it really gets interesting.

nggggh yeahhhh i haaave.... four boards, took me... four months i think? it was one of the first PCBs i'd ever done myself, i went, "no way i can do this using a soldering iron, not comfortable with a heat-gun... let's get an IR solder station". cooked the first break-out board from sparkfun, taught me a lesson that one (what... you think i'd try it with a real PCB??) - most of the time was because i got a Eurocircuits "prototype bare PCB" - no silkscreen, just completely solder-dipped copper - and then put on components only in groups (starting with power) testing as i went.

if you're interested - [rhombus-tech.net]

so yes. QFNs, QFPs, and 0402 components... jaezuss

i've also managed BGA 660 0.6mm pitch (the RK3288) and 96 FBGA DDR3 RAM ICs with a heatgun. gaaah, what a pain - wasted about 4 or 5 processors that way until i got one right...

Oh lord, that laptop board looks like a nightmare lol. I've done similar BGA's with a hand iron as well. Drag the pins and pray..

Edited 1 time(s). Last edit at 10/04/2017 01:21PM by obelisk79.

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obelisk79
Oh lord, that laptop board looks like a nightmare lol. I've done similar BGA's with a hand iron as well. Drag the pins and pray..

squash, squash...

the laptop board was a lot of fun. first "real" major board i did myself completely (design, assembly). getting it into the available space.... yyeah, that one's awkward.

ok so 30-40% done: components done, am on to the connectors. i'll leave off the MOSFETs, MicroSD and the buffer for now. i'm used to doing TSOP packages but after seeing how small it is i don't think it would be fair to other people considering doing this by hand, so i'll investigate if SOP-14 will actually fit on the board. for the MicroSD there's space, but for the MOSFETs it's going to be tight. might find another location for the HC125... we'll see.

sigh i just realised i put D1 on backwards...

using the heatgun to put the 0805 components on... honestly... it's a pain. i found i was better off pinning them down (so they don't move) with the multimeter probe and just a quick dab with the soldering iron. the electrolytic capacitors are a pain! i had to pre-tin them to make sure to get good contact, then a tiny blob of solder at the end (most of the wire contact is *under* the actual capacitor...) then use the heat-gun to heat things up to the point where the capacitor settled down slowly onto the board.

overall it's quite simple, but i still can't quite get over how many damn holes there are. RAMPS is *not* a board that's designed for manufacture!!

the pcb needs some of sort of additive manufacturing technique vs the subtractive systems

3d printed/constructed fr-4 anyone?

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Dust
the pcb needs some of sort of additive manufacturing technique vs the subtractive systems

3d printed/constructed fr-4 anyone?

there are actually some companies that can do 3D-printed PCBs. i wouldn't bet on them being able to handle 10+ Amps though!

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lkcl
there are actually some companies that can do 3D-printed PCBs. i wouldn't bet on them being able to handle 10+ Amps though!
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I knew there was Sputter deposition for deposition of copper tracks and via creation is already additive threw the 'magic' of chemistry, but have not seen anything about the additive substrate layers...

There is also all these conductive ink stuff but thats very low current... and doesn't help with all the holes!

Just a thought, I wonder if D1 would be better space wise as a SMD, and one of those cut able pcb jumpers... (two half circle with track between them, Im sure it has a name, but I don't know it) So it can be removed without heat..

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lkcl
ok so 30-40% done: components done, am on to the connectors. i'll leave off the MOSFETs, MicroSD and the buffer for now. i'm used to doing TSOP packages but after seeing how small it is i don't think it would be fair to other people considering doing this by hand, so i'll investigate if SOP-14 will actually fit on the board. for the MicroSD there's space, but for the MOSFETs it's going to be tight. might find another location for the HC125... we'll see.

...
using the heatgun to put the 0805 components on... honestly... it's a pain. i found i was better off pinning them down (so they don't move) with the multimeter probe and just a quick dab with the soldering iron. the electrolytic capacitors are a pain! i had to pre-tin them to make sure to get good contact, then a tiny blob of solder at the end (most of the wire contact is *under* the actual capacitor...) then use the heat-gun to heat things up to the point where the capacitor settled down slowly onto the board.

It's much easier to use a hotplate. There are tutorials on use a hotplate to do SMD soldering on the web. It's even easier of you use a Mylar stencil to apply the solder paste (I get Mylar stencils made by smdstencil.co.uk).

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lkcl
overall it's quite simple, but i still can't quite get over how many damn holes there are. RAMPS is *not* a board that's designed for manufacture!!

Absolutely. lt would cost less to produce an all-in-one controller board than Arduino and RAMPS separately, in the same volumes. And even less using a modern ARM processor instead of the obsolescent (and therefore expensive) ATMEGA2560.

Edited 1 time(s). Last edit at 10/05/2017 09:26AM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

ha! D8 through D11 work (no MOSFETs connected yet). stepper driver x works. pin-configuration is a pain: the pin-mappings are virtual (from the Arduino IDE) not physical (from the actual Arduino schematic). took me an hour going over the source to work that out: it doesn't help that the pins D0 to D15 are all identical in both the IDE and the Arduino Mega pin-numbering...

anyway i'm using some of the ADC pins as Digital I/O, what that ends up meaning is that you have to add 54 to the "Analog" pin number 0-15 to get it to act as a Digital pin. looking at the MEGA2560 datasheet it turns out that ADC is actually an "Alternative Function".

ok let's do a couple more steppers then move on to the endstops. once i'm happy with that i'll put the MOSFETs in. i shouldn't have to do too much else in the way of code as there already exists a "Power On" pin, which i'm using to switch on the MOSFETs...

*sigh* i frickin can't stand these frickin polulu modules what the hell, just blew one up by plugging it in backwards, damnit. why the hell didn't they design them so that they can only be put in one way??

I am going to lurk out here for a while... learning lots and have little to input

thanx for letting me shoot some input tho

I think I want one of these when it gets a little more traction....

"*sigh* i frickin can't stand these frickin polulu modules what the hell, just blew one up by plugging it in backwards, damnit. why the hell didn't they design them so that they can only be put in one way?? "

They did, electrically

As your aware the entire pololu form factor is just one stupid decision after another... but all attempts at replacing it with something better have failed thus far..

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Dust
Just a thought, I wonder if D1 would be better space wise as a SMD, and one of those cut able pcb jumpers... (two half circle with track between them, Im sure it has a name, but I don't know it) So it can be removed without heat..

yyeahh that's a good idea - i'm doing an stm32L471 arduino-clone, the atmega2560 reference design it's based on has a decent beefy SMT diode, i'll cut/paste that. can't remember what the name is either

I also wonder if you can get SMD .1" connector strips... that would remove a bunch of holes

Oh you can (not really surprising)





Edited 1 time(s). Last edit at 10/05/2017 08:52PM by Dust.