CRAMPS
Release status: experimental
| Description | Cape-RAMPS for BeagleBone
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| License | GPL
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| Author | |
| Contributors | |
| Based-on | |
| Categories | |
| CAD Models | KiCAD
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| External Link |
Cape-RAMPS For BeagleBone
This is currently a work-in-progress, modifying the RAMPS-FD design for use on the BeagleBone. The schematic is very similar, with changes mostly to the power and ESTOP logic to account for differences from the Due and the expected use of LinuxCNC for machine control.
Design Rational
While the available BeBoPr and Replicape 3D printer capes for the BeagleBone are excellent designs, they lack the simplicity and low-cost of the proven RAMPS design. The RAMPS-FD for the Due solves most of the issues related with porting RAMPS to the BeagleBone (mostly related to 3.3V vs. 5V I/) and was used as the starting point for this design.
Given the loss of I/O pins on the BeagleBone Black due to the on-board HDMI and eMMC flash, it was not possible to map the RAMPS-FD I/O pins one-to-one onto the BeagleBone. Priority was given to the HDMI pins, which are unused by the CRAMPS cape so the BeagleBone can run stand-alone. To support all the I/O required for the RAMPS-FD design, some pins must overlap with the eMMC pins, meaning they are unusable if you wish to run the BeagleBone from the on-board flash instead of a uSD card. Finally, a choice needed to be made between leaving some pins available for expansion (UART, I2C) and requiring the eMMC be disabled to use some features (like the E1 and E2 extruders). I decided to go with maximum functionality on the base board in preference to future expansion in most cases. Only the servo lines are mapped to the eMMC and are unusable without running from a uSD card, which allows the SPI pins to be available for possible addition of the 4 or 6 axis RAMPS-FD-EXT expansion board or other SPI connected expansion. All motor drivers, limit switches, and FET outputs are available when booting from a BeagleBone Black using the on-board flash and HDMI output.
Pins have been assigned such that if the E1 or E2 extruder outputs are not needed, several UART/I2C lines are freed up for use with expansion logic. Any free pins (including the eMMC and HDMI pins, if these functions are disabled) may also be used as GPIO.
Features
Identical to RAMPS-FD except for some of the expansion headers:
- Six Pololu stepper driver sockets
- Four high-current FET outputs for heaters
- Four thermistor inputs for temperature sensing
- Two low-current 12V FET outputs for fans/LEDs
- Six limit switch inputs
- Four servo outputs (requires disabling on-board eMMC flash)
- One UART and one I2C header are always available
- Additional UART and I2C signals are available if E1 or E2 is unused
Sources
Source files are hosted on github: github.com/cdsteinkuehler/bobc_hardware/tree/CRAMPS/CRAMPS
