Digisparc idea..

[Paul Schulz]

Hi Pix, Jonathan, et.al

Mainly after some qualifying information on the following idea.. of
using the digispark and stackable shields, to create expandable RAMPS
interface (via i2c).

- What is the existing interface to the RAMPS servo drivers from the arduino?

eg. Make a RAMPS driver which can be stacked on the digisparc (with
separate power supply) to allow an arbitary number (1-8 say) of
stepper motors.
.. or am I totally missing the point.

Cheers,
Paul

On Thu, Aug 16, 2012 at 1:01 PM, Ken <k...@waggies.net> wrote:
> Couldn't an editable list of names and parts be created on the hackerspace
> blog/website, with a cutoff date ?
>
> Ken (not ordering any, but watching with a smile)
>
>
>
> On 16 August 2012 12:43, Steven Pickles <thatp...@gmail.com> wrote:
>>
>> ooh, can I add a boost shield too?
>>
>> i can imagine keeping track of this is getting pretty crazy ;)
>>
>> pix
>>
>>
>> On 16 August 2012 13:04, Paul Schulz <pa...@mawsonlakes.org> wrote:
>>>
>>> Paul Schulz (total order for me)
>>> - 2x Digisparc
>>> Shields PCBs
>>> - 2x Though hole dev shield
>>> - 2x Boost Shield
>>> Shield Kits
>>> - 2x RGB Kit (Blinking LED)
>>>
>>> Thanks for doing this.
>>>
>>> On Thu, Aug 16, 2012 at 11:53 AM, Jamie Mackenzie
>>> <jrrmac...@gmail.com> wrote:
>>> > Hmmm, good call Tamsyn.
>>> >
>>> > Make mine an RGB shield kit. :)
>>> >
>>> >
>>> > On 16 August 2012 11:29, Thomas Sprinkmeier
>>> > <thomas.sp...@gmail.com>
>>> > wrote:
>>> >> Please add 2 blinkenlights kits please to my 2 requested digisparks.
>>> >>
>>> >> I love the 'low power' feature, a marked area on the PCB to mutilate
>>> >> with a Stanley knife to disable the LED's and save power.
>>> >>
>>> >> Thomas
>>> >>
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[Steven Pickles]

Err, the digispark is a tiny arduino. The AM in rAMps is "Arduino Mega"... You control RAMPS by talking to the Arduino Mega over the USB connection. What benefit would there be in having the Digispark talk to the Arduino?

pix

[Paul Schulz]

Sorry.. didn't know what the AM stood for.. (now I do).
So.. replace the ArduinoMega with the Didgisparc.. -> RDSPS Not quite
the same ring to it. I need to do some more reading.

[Steven Pickles]

Ahh that definitely wouldn't work. The RAMPS boards needs a lot of pins to do all of its work. Some very early Reprap hardware used the Duemilanove but it maxxed out all of the pins, hence the move to the Mega. Actually the "Sanguino" was the a pre-mega response to the pinout-exhaustion of running a reprap from a standard arduino.

Unless of course you can find some fancy I2C stepper drivers and heating/temp measurement modules.

pix

[Jonathan Wheare]

Spark fun have recently started selling a carrier for an SPI stepper driver.  Its more expensive than the pololu drivers, but adds stall detection and the ability to specify rate rather than just step and direction. I think you would still need a few more pins. J.

[Steve Roehrs]

 

I think the stacking might interfere with any heatsinks that you put on the stepper drivers too, though I don't have any experience with how hot they get.

Assuming you could sort the hardware out (a stack of shields that only use the I2C interface - one per stepper, and maybe one or two others with I2C expanders for the other I/O pins) - does the Digispark have enough RAM and Flash to run the control software?

 

Arduino Mega : 128KB flash, 8KB RAM

Attiny85 (digispark) : 8KB flash, 512 bytes RAM

 

Could be a bit of a squeeze :)

 

Cheers,

 

Steve