Objective:
- Construct a system capable of controlling a CNC machine using closed feedback control loops.
- Build the controller to run on a bare metal environment on the RaspberryPi module.
- Design the code to abstract away hardware so that it is possible to run on an arbitrary CNC.
Demonstration Video
Introduction to the CNC Controller
We built a CNC controller in bare metal capable of reading in a GCode file, interpolating motor positions, and setting the motors to move a spindle to those positions in a closed feedback loop. In order to accomplish this in a bare metal environment, the RaspberryPi needed to be configured to setup the parts of the processor's peripherals that would be needed - timers, interrupts, UART controller, GPIOs, etc. Once configured, we were able to start building out modules to handle path planning and stepper motor control.
Code Appendix
The entire code for the project is held on a public GitHub repository linked here.
Bill of Materials
| Part | Quantity | Price | Link |
|---|---|---|---|
| RaspberryPi 2 | 1 | $0 | Provided |
| Jumers, Wires, Breadboard | - | $0 | Provided |
| ams AS5161 Absolute Encoder | 3 | $28.02 | Link |
| D82DIA Diametric Magnet (for encoders) | 3 | $3.39 | Link |
| TOTAL: | - | $31.41 | - |
References and Acknowledgements
Professor Joe Skovira
grbl
nraynaud's GCode Simulator
Valvers tutorials on bare metal programming
David Welch
Image of CNC Machine
Image of Wood
Bootstrap
Contact
Nikita Ermoshkin
ne75@cornell.edu
Worked on developing the bare metal environment, including the ARM startup code, as well as the stepper driver for the motion control system.
Brendan Quinn
bjq6@cornell.edu
Designed and implemented the positioning software, including GCode parsing for path interpretation and step interpolation.