pycnc 1.1.0
CNC machine controller
License: MIT
Keywords: CNC 3D printer robot raspberry pi

|Build Status|

.. figure:: https://cloud.githubusercontent.com/assets/8740775/26766365/14796b54-4999-11e7-8ca2-9428a45878ab.png
   :alt: 

PyCNC is a free open-source high-performance G-code interpreter and
CNC/3D-printer controller. It can run on a variety of Linux-powered
ARM-based boards, such as Raspberry Pi, Odroid, Beaglebone and others.
This gives you a flexibility to pick a board you are most familiar with,
and use everything Linux has to offer, while keeping all your G-code
runtime on the same board without a need to have a separate
microcontroller for real-time operation. Our choice of Python as main
programming language significantly reduces code base compared to C/C++
projects, reduces boilerplate and microcontroller-specific code, and
makes the project accessible to a broader audience to tinker with.

Realtime Motor Control in Linux?
================================

| Typically there is no way to control stepper motors from Linux runtime
  environment due to the lack of real time GPIO control. Even kernel
  based modules can not guarantee precise control of pulses for
  steppers. However, we can use a separate hardware module, DMA (Direct
  Memory Access) which provides high precision for GPIO outputs. This
  module can copy bytes which represent GPIO states from RAM buffer
  directly to GPIO with some clock based on main chip internal
  oscillator without using CPU's cores. Using such approach this project
  generates impulses for moving stepper motors and that is very precise
  way regardless CPU load and OS time jitter.
| This approach also allows to use Python language for this project.
  Typically, Python is not good choice for real time application, but
  since project just needs to set up DMA buffers and hardware will do
  the rest, Python become the perfect choice for easy development of
  this project.

| Video demo - `YouTube video <https://youtu.be/41wdmmztTNA>`__
| And the original video when PyCNC was just a prototype `YouTube
  video <https://youtu.be/vcedo59raS4>`__

Current gcode and features support
==================================

-  Commands G0, G1, G2, G3, G4, G17, G18, G19, G20, G21, G28, G53, G90,
   G91, G92, M2, M3, M5, M30, M84, M104, M105, M106, M107, M109, M114,
   M140, M190 are supported. Commands can be easily added, see
   `gmachine.py <./cnc/gmachine.py>`__ file.
-  Four axis are supported - X, Y, Z, E.
-  Circular interpolation for XY, ZX, YZ planes is supported.
-  Spindle with rpm control is supported.
-  Extruder and bed heaters are supported.
-  Hardware watchdog.

Watchdog
========

PyCNC uses one of DMA channels as hardware watchdog for safety purpose.
If board, OS or PyCNC hangs this watchdog should disable all GPIO
pins(by switching them into input state, for RPi this would be GPIO0-29)
in 15 seconds. Since there is a high current and dangerous devices like
heated bed, extruder heater, this feature should prevent uncontrollable
overheating. But don't count on such software features too much, they
can hang too or output MOSFET become shorted, use hardware protection
like thermal cutoff switches in your machines.

Hardware
========

| Currently, this project supports Raspberry Pi 1-3. Developed and
  tested with RPI3. And there is a way to add new boards. See
  `hal.py <./cnc/hal.py>`__ file.
| *Note: Current Raspberry Pi implementation uses the same resources as
  on board 3.5 mm jack(PWM module), so do not use it. HDMI audio works.*

Config
======

| All configs are stored in `config.py <./cnc/config.py>`__ and contain
  hardware properties, limitations and pin names for hardware control.
| Raspberry Pi implementation should be connected to A4988, DRV8825 or
  any other stepper motor drivers with DIR and STEP pin inputs. Default
  config is created for Raspberry Pi 2-3 and this wiring config:

+-------------------+----------------+----------------------------+-------------------+
| Circuit name      | RPi pin name   | RAMPSv1.4 board pin name   | Note              |
+===================+================+============================+===================+
| X step            | GPIO21         | A0                         |                   |
+-------------------+----------------+----------------------------+-------------------+
| X dir             | GPIO20         | A1                         |                   |
+-------------------+----------------+----------------------------+-------------------+
| steppers enable   | GPIO26         | A2, A8, D24, D34, D38      | all steppers      |
+-------------------+----------------+----------------------------+-------------------+
| Y step            | GPIO16         | A6                         |                   |
+-------------------+----------------+----------------------------+-------------------+
| Y dir             | GPIO19         | A7                         |                   |
+-------------------+----------------+----------------------------+-------------------+
| Z dir             | GPIO13         | D48                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| Z step            | GPIO12         | D46                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| E1 step           | GPIO6          | D36                        | reserve           |
+-------------------+----------------+----------------------------+-------------------+
| E1 dir            | GPIO5          | D34                        | reserve           |
+-------------------+----------------+----------------------------+-------------------+
| E0 dir            | GPIO7          | D28                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| E0 step           | GPIO8          | D26                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| Z max             | GPIO11         | D19                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| Z min             | GPIO25         | D18                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| Y max             | GPIO9          | D15                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| Y min             | GPIO10         | D14                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| X max             | GPIO24         | D2                         |                   |
+-------------------+----------------+----------------------------+-------------------+
| X min             | GPIO23         | D3                         |                   |
+-------------------+----------------+----------------------------+-------------------+
| heater bed        | GPIO22         | D8                         |                   |
+-------------------+----------------+----------------------------+-------------------+
| heater 2          | GPIO27         | D9                         | uses for fan      |
+-------------------+----------------+----------------------------+-------------------+
| heater 1          | GPIO18         | D10                        |                   |
+-------------------+----------------+----------------------------+-------------------+
| ser 1             | GPIO17         | D11                        | reserve           |
+-------------------+----------------+----------------------------+-------------------+
| ser 2             | GPIO15         | D6                         | reserve           |
+-------------------+----------------+----------------------------+-------------------+
| ser 3             | GPIO4          | D5                         | reserve           |
+-------------------+----------------+----------------------------+-------------------+
| ser 4             | GPIO14         | D4                         | reserve           |
+-------------------+----------------+----------------------------+-------------------+
| I2C SCL           | GPIO3          | -                          | to ads111x        |
+-------------------+----------------+----------------------------+-------------------+
| I2C SDA           | GPIO2          | -                          | to ads111x        |
+-------------------+----------------+----------------------------+-------------------+
| ads1115 ch0       | -              | A15                        | heater 2 - nc     |
+-------------------+----------------+----------------------------+-------------------+
| ads1115 ch1       | -              | A14                        | bed sensor        |
+-------------------+----------------+----------------------------+-------------------+
| ads1115 ch2       | -              | A13                        | extruder sensor   |
+-------------------+----------------+----------------------------+-------------------+
| ads1115 ch3       | -              | -                          | not connected     |
+-------------------+----------------+----------------------------+-------------------+

| So having Raspberry Pi connected this way, there is no need to
  configure pin map for project. `RAMPS
  v1.4 <http://reprap.org/wiki/RAMPS_1.4>`__ board can be used for this
  purpose. Full reference circuit diagram and photos of assembled
  controller(click to enlarge):
| |circuit small| |sample front small| |sample back small| |sample
  mounted small|

Usage
=====

| Just clone this repo and run ``./pycnc`` from repo root. It will start
  in interactive terminal mode where gcode commands can be entered
  manually.
| To run file with gcode commands, just run ``./pycnc filename``.
| Optionally, ``pycnc`` can be installed. Run

.. code:: bash

    sudo pip install .

in repo root directory to install it. After than, ``pycnc`` command will
be added to system path. To remove installation, just run:

.. code:: bash

    sudo pip remove pycnc

Performance notice
==================

| Pure Python interpreter would not provide great performance for high
  speed machines. Overspeeding setting causes motors mispulses and
  probably lose of trajectory. According to my tests, Raspberry Pi 2 can
  handle axises with 400 pulses on mm with top velocity ~800 mm per min.
  There is always way out! :) Use JIT Python implementation like PyPy.
  RPi2 can handle up to 18000 mm per minute on the machine with 80 steps
  per millimeter motors with PyPy.
| *Note: Raspbian has outdated PyPy version in repositories(v4.0).
  Moreover v4.0 has issue with ``mmap`` module implementation. Use PyPy
  v5.0+, download it for your OS from
  `here <https://pypy.org/download.html>`__.*
| PyPy installation:

.. code:: bash

    wget wget https://bitbucket.org/pypy/pypy/downloads/pypy2-v5.7.1-linux-armhf-raspbian.tar.bz2
    sudo mkdir /opt/pypy
    sudo tar xvf pypy2-v5.7.1-linux-armhf-raspbian.tar.bz2 --directory /opt/pypy/ --strip-components=1
    sudo ln -s /opt/pypy/bin/pypy /usr/local/bin/pypy

Project architecture
====================

.. figure:: https://user-images.githubusercontent.com/8740775/27770129-c8c3592c-5f41-11e7-8a9c-254d5a88ed77.png
   :alt: 

Dependencies
============

Nothing for runtime. Just pure Python code. For uploading to PyPi there
is a need in ``pandoc``:

.. code:: bash

    sudo dnf install pandoc
    sudo pip install pypandoc

GCode simulation
================

Just a link, mostly for myself :), to a nice web software for gcode
files emulation (very helpful for manual creating of gcode files):
https://nraynaud.github.io/webgcode/

License
=======

see `LICENSE <./LICENSE>`__ file.

Author
======

Nikolay Khabarov

.. |Build Status| image:: https://travis-ci.org/Nikolay-Kha/PyCNC.svg?branch=master
   :target: https://travis-ci.org/Nikolay-Kha/PyCNC
.. |circuit small| image:: https://user-images.githubusercontent.com/8740775/28233810-40773186-6902-11e7-8496-5750babfcf44.jpg
   :target: https://user-images.githubusercontent.com/8740775/28233650-d64060e0-6900-11e7-8605-6475384fd2f7.png
.. |sample front small| image:: https://user-images.githubusercontent.com/8740775/28233812-407820c8-6902-11e7-8de1-35c03509c0e5.jpg
   :target: https://user-images.githubusercontent.com/8740775/28233649-d6402800-6900-11e7-8dca-cd35c8292e0c.jpg
.. |sample back small| image:: https://user-images.githubusercontent.com/8740775/28233879-db96ea1c-6902-11e7-9298-11150476084b.jpg
   :target: https://user-images.githubusercontent.com/8740775/28233648-d63fa0c4-6900-11e7-8fab-2055e035a6cb.jpg
.. |sample mounted small| image:: https://user-images.githubusercontent.com/8740775/28233811-40777e8e-6902-11e7-8899-5991860d182c.jpg
   :target: https://user-images.githubusercontent.com/8740775/28233652-d65f82ea-6900-11e7-9e80-d8b0c9238f95.jpg