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Table of Contents
pr0ncnc is the standard platform that I use to build my CNC microscopes. A typical system consists of:
- uvscada for high level control
- AmScope MU800 camera
- Driver box
- BBB running machinekit
- BBB cape w/ optional CD4050 3.3V ⇒ 5V boosters
- XYZ output standard
- Connected over USB w/ static USB-ethernet bridge IP
- Case: Hammond 1591-E
- IMS MDrive stepper motors (such as MDrive17 or MDrive23)
- Linear stages vary
- Step/direction connectors: Combicon 4 pin
- TODO: move to mini connectors
- Where applicable, bipolar motors use Combicon 5 pin
BBB bolt pattern
- WARNING: not square. According to breakout.py:
- 0.000, 0.000
- 0.000, 1.900
- 2.600, 0.125
- 2.600, 1.775
- For 4-40 standoffs into case
- Standoffs are CA glued in
- Standoffs should not peek out other side
- Consider putting Kapton on back in case they stick through slightly
- Need tight fit. Drill size?
Motor connector
Although there is a de-facto DB25 standard for step/direction pulses (from Compumotor?), I don't like DB25 connectors. Instead I use Combicon connectors since I can quickly wire them up and plug/unplug them.
#29 drill for panel mount Combicon bolt holes using 6-32 SHCS
Cable colors
- Step+: red (left)
- Step-: black
- Dir+: blue
- Dir-: white (right)
BBB 5V cape
Based on CRAMPS pinout
P8
| Pin | CPU GPIO | CNC function | I/O | Note |
|---|---|---|---|---|
| 12 | gpio1[12] | X dir | O | |
| 13 | gpio0[23] | X step | O | |
| 14 | gpio0[26] | Y dir | O | |
| 15 | gpio1[15] | Y step | O | |
| 18 | gpio2[1] | Z dir | O | |
| 19 | gpio0[22] | Z step | O |
I'd like to stick with 5 V CMOS style outputs since all my units can take those
- Traditional drivers are optocopulers and take resistor limited +/- 5V inputs
- MDrive17, MDrive23 basically 5-24V open drain but can also operate CMOS
IMS MDrive probably don't take much current (TODO: verify)
My Compumotor M-Drive requires 20 mA min
- CD4050 can typically only source 3 mA or so
- HEF4050 can do 20 mA max…borderline
- Sparkfun BOB-12009 theoretically can do 220 mA
Originally I shied away from the BOB, but think I can simplify the soldering process to make it more attractive
BBB pinout
Camera calibration
Put white piece of paper under camera
Run manbal.py to get RGB values
Adjust V4L controls until balanced
Place V4L control values into microscope.json
- see example configs for specific usage