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Yellobello
Other questiion:
When I would use Machinekit togehther with the BBB.. will it be realtime linux pulsing the stepper drivers straight with the CPU´s I/O or is it using the separate microcontrollers for this task?

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TomWS
Looking at the Rev. V2.1 schematic, I see you have provision for a Cape Identification EEPROM. Is this necessary for the latest MachineKit image to recognize the cape? If so, is the EEPROM contents documented somewhere?

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cdsteinkuehler
I am working on a BeagleBone Cape version of the RAMPS design, called CRAMPS. I have a stub page created in the RepRap wiki, and KiCAD design files are on github. The design is based primarily on the RAMPS-FD, with changes where needed for the BeagleBone.

The schematic is mostly complete except for assigning some I/O on the BeagleBone P8/P9 pin headers, which I will do based on the PCB layout (in progress). I would appreciate any design review or comments on the schematic.

Features are pretty much identical to the RAMPS-FD, except for the AUX expansion connectors. There is an SPI interface available that will work with the RAMPS-EXT extruder expansion boards, and an I2C header. Both the I2C and SPI headers are 5V tolerant, to allow easier interfacing to existing 5V Arduino add-ons. I plan on using pass-through connectors to support additional expansion, so the large AUX4 connector has been removed, and the AUX2 analog connector has been modified to allow direct interfacing to a 4-wire resistive touch-screen.

Questions and comments welcome!

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kroylar
What have you done with this in the newer versions of the board? Particularly, I see that a fully assembled v2.2 board is available from pico-systems. What is the state of the thermistor readings at room temperature with this version?

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cdsteinkuehler
The only thing not really working as expected is the thermistor inputs. The signal levels are so low at room temperature with a 1.8V ADC range that the leakage from the protection diodes is causing measurement offsets. I am considering simply removing the protection diodes from the next version (I have already removed them from my prototype), as I'm not sure they really help all that much. The right way to protect the inptus is with a high input impedence insturmentation amplifier, but that costs money and adds complexity. The design still has a 4.7K series resistor to help protect the analog inputs, which probably puts the BeagleBone about even with the Arduino Mega used with the original RAMPS (which had absolutely *NO* analog input protection at all, but the AVR is likely a bit more robust than the AM3358 on the 'Bone).

If you have any strong opinions about keeping or removing the analog input protection, let me know.

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NoobMan
US price probably does not include vat because they dont have that. EU price probably includes it, most probably all components have that included in purchase price. So the eu price is comparable if you keep track of vat. If one would want to import large quantities or merchandise from us to eu, would have to pay vat at customs, the vat in the country where the import is made. Sort of speaking, can not avoid eu vat indefinatelly nor completely.