Base48 CNC controller
From base48
Base48 CNC controller
Founder:
hyna
Coops:
rmarko, arius, hexo
HW License:
CERN OHL?
Status:
active
Created:
2013-06-18
Last Modified:
2013-06-29
Contents
Spec
- 24V PWR supply
http://www.pololu.com/catalog/product/2132/faqs
- 12V for extruder fan?
- 5V ?(USB)
- 3V3 for MCU and drivers? (USB)
- 32-bit MCU
- must be compatible at least with dual extruder
- robust design, but cheap as much as possible
- compatible with rPi? Octopus...
- usb, ethernet?
- thermistor and heater integrated in extruder connector.
- separate power input for heatbed?
Fixed spec
- native support only for one extruder (2nd extruder support, but without stepper driver).
- 4x Stepper motor drivers DRV8825 (1/32 ustep) + 1 breakout
- SD card support
- micro USB connector
- 2x thermistor (+1 breakout)
- 1x 12V for extruder FAN
- 1x 12V PWM for print cooling
- header for display
TODO
- decision about MCU (risk of long term obsolescenc)
- should we use onboard motor drivers, or "stepstick" style
- how to adjust current trough the motors? Analog or digital potentiometer? (quad version is quite common, but we need one more for aditional extruder). Another way is to use PWM and RC filter.
DRV8825
- 1 - Charge pump: Connect a 0.01-μF 50-V capacitor between CP2 2 IO Charge pump flying capacitor CP1 and CP2.
- 2 - Charge pump: Connect a 0.01-μF 50-V capacitor between CP2 2 IO Charge pump flying capacitor CP1 and CP2.
- 3 - VCP: Connect a 0.1-μF 16-V ceramic capacitor to VM (+24V).
- 4 - Motor VCC: +24V (Or 12V?)
- 5 - MOTOR A1
- 6 - ISENS: Resistor to GND
- 7 - MOTOR A2
- 8 - MOTOR B1
- 9 - ISENS: Resistor to GND
- 10 - MOTOR B2
- 11 - Motor VCC: +24V (Or 12V?)
- 12 - Motor current setting: pin 12-13 connected together. Connected to output from digital potentiometer. 3,3V or Vref?
- 13 - Motor current setting: pin 12-13 connected together. Connected to output from digital potentiometer. 3,3V or Vref?
- 14 - GND: To GND
- 15 - 3V3 OUT: Max 1 mA. Can be used as Vref for motor current limitation. Bypass to GND with a 0.47-μF 6.3-V ceramic capacitor.
- 16 - RESET: Permanently to High.
- 17 - SLEEP: Permanently to High.
- 18 - FAULT: To MCU GPIO pin
- 19 - DECAY: for steppers mixed mode => leave unconnected
- 20 - DIRECTION: To MCU
- 21 - ENABLE: To MCU
- 22 - STEP: To MCU
- 24 - u stepping: jumper or via MCU to High (internal pulldown)
- 25 - u stepping: jumper or via MCU to High
- 26 - u stepping: jumper or via MCU to High
- 27 - HOME: useless signal. Not Connected
- 28 - GND: To GND
