We just started our Indiegogo campaign for BMA&DICE a new, RAMPS compatible, electronics.
This electronic, supports much powerful stepperdrivers and also allows to plug in many more different driver pcbs.

The standard DICE will be the DICE-STK which allows up to 3A RMS to the steppers and up to 128x substepping for extra precision.
If you are interested take a look at: [igg.me]

The whole proect will be opensource, the hardware will be released as open hardware, and any created software as GPL.

If you have any ideas or comments, please contact us.

--
The 2PrintBeta Team

Q's:

1. Since most of the communication to the stepper drivers is done via SPI, is there any clock syncronisation used to ensure all the steppers step at the same time, or are you simply relying on the SPI commands to be followed as soon as they're received?

2. Is there any reason that you didn't go 3.3V (using say an Arduino Due) rather than sticking with 5V (and the Arduino Mega)?

3. Given most 200mm PCB heated beds tend to run right on the 10A mark, and people are looking at larger beds on some machines, is there a reason that you've set the max current to 10A instead of 15A (giving a bit more headroom)?

Hello,

A:
1. The SPI driven DICE-L6470 has also a "step clock" signal, routed to the available GPIOs, so it is possible. The DICE has to be configured in advance and can be clocked independently
or synchronized with other DICEs.

2. Indeed, the Arduion DUE would be great. I will take a look on the connectors. Thanks for your suggestion!
The DICEs have not be tested on 3.3V completely. They are planned to be compatible. For some functions, compatible logic (e.g. the 74LVC... family) is needed and it depends on the available space
on a single DICE, but we are taking account of it to be as flexible as possible.

3. We thought about a bigger fuse for the heat bed switch. At the moment the design, including the layout, is only tested up to 10A. Should be possible to attach a 15A fuse, but we have to make some
additional thermal tests. Don't want you, to burn your workshop. :-)

Best regards
--
Konrad - 2PrintBeta

Hello,

Another point for why we choose 5V and the Arduino Mega is, software compatibilty. With a Arduino Mega based shield nearly all opensource 3D printer firmwares can be used unchanged.
For the same reason, the default stepper drivers (DICE-STK) use the step/clock interface and not SPI. SPI is optional for other, more intelligent DICE boards.

But it should not be too hard to create a future 3.3V BAM Shield with 3.3V DICEs for the Arduino Due.
So if this project works out as planned, this will probably be the next step.

kind regards,
Dominik - 2PrintBeta

Please correct DICE-STK specification: Current: 2.1A RMS (3A max.)
I think was probably copy-paste from L6470.

Just to be a little more clear, its on the indiegogo page:

DICE-STK [...] Specifications:
*    Logic voltage: 5V
*    Supply voltage: 9V - 35V
*    Current: 3A RMS (7A max.) <-> Current: 2.1A RMS (3A max.)  ->(or check datasheet absolute max)
*    Size: 51 x 43 mm

Edited 1 time(s). Last edit at 03/29/2014 03:11PM by NoobMan.

Oh, you are correct. Thanks for noticing this copy&paste error.

I just checked the datasheet for that chip and our internal documentation again, and according to the calculations ist should be 2.4A RMS with 3A max.
We should probably do some load tests in the next days to find out the real max (not only calculations) with and without activ cooling/heatsinks.

thanks
2PrintBeta - Dominik

Hi NoobMan,

Yes, you are right. There is a error. We will change it asap, thanks.
I will further do some tests to check the heat dissipation.

Thanks for your replies. It's good to see that, unlike a lot of other projects that post their Kickstarters on here, you're interacting with the community (at least, so far).

I like the idea, but im not so sure the mega family has much life left in it.

Another DICE board to consider making is around the [www.trinamic.com]
2.6A, 256 micro stepping and some of their other cool tech.. is a SPI and Step/direction interface

That trinamic chip is very nice, although not cheap.
Would also fit perfectly for a 3.3V Arduino Due compatible Shield with 3.3V DICEs.

Thank you for the hint.

Dominik - 2PrintBeta

Hello there,

thanks again for the info about the Trinamic driver. We did it and implemented it to one of the DICE-boards (DICE-TMC).
We licensed all with CERN OHL V.1.2. to give the most possible use for all community members.
I'm not shure if can find it via google at the moment, because we released it recently (today) in the 2PrintBeta.de webshop.
In the webshop's article you can find the schematics for the boards.

I would greatly appreciate, if you would like to read our blog article at ifeelbeta.de about BAM&DICE.
Any comments? Please let me know.

Konrad - 2PrintBeta

I agree, I'm moving all my hobby stuff (printer, router, radio control) to 32-bit platforms.

The 8-bit field already has many options, what we need are more 32-bit higher speed options.

The Due is nice but I'd like to see the RAMPS (modular) philosophy adapted to the 120Mhz LPC1769 used in the Smoothie stuff. A six slot modular shield using the LPCXpresso in a CPU slot would be great.