Firmware / Embedded Microcontroller based Computer Numerical Control

Dedicated Motion Controllers translate a path description (typically G-CODE) into signals (typically Step and Direction) in real time to drivers that then cause stepper or other motors to move the axis of a machine. This can be done on a PC via CNC Applications, but because standard operating systems are NOT design for real time control, it can be best to use a seperate embedded motion controller and simply relay G-CODE or other commands from the main system.

Common examples are the ubiquitous Marlin^ / RAMPS combination for 3D printers, and grbl^ / shield or TinyG^ / sheild for CNC. An ultra low cost opiton is our BOB Motion Control g-code to multi-axis step/direction motor driver. These accept G-CODE but have no other user interface. A program like Universal G-CODE Sender can provide a minimal interface. They put out step and direction commands via the Pololu compatible headers. This can be adapted to the PMinMO standard by our Adapter Cable

In some cases, a PC based CNC application can work closely with the embedded unit to provide a seamless user interface with GUI controls. For example, https://www.poscope.com/product/pokeys57cnc/ is a MACH 3 recommended USB Motion Controller with PMinMO compatible connectors for direct connection to open source stepper drivers like the THB6064AH or Linistepper or servo drivers like the BOB PID.

Stepping Motion Profile Motion panning overview. Stepper motor specific, but with good general information.

3D Line to Stepper Axis Pulses in a PIC16F Naive motion control

A common language for specifying the desired location and speed of movement is G-CODE

Also:

• Motion Control Methods

See also:

• https://planet-cnc.com/hardware/#products-hardware Planet CNC USB and USB/Ethernet Motion Controllers are PMinMO compatible.
• https://www.poscope.com/PoKeys57CNC a USB Motion Controller with PMinMO compatible connectors for direct connection to open source stepper drivers like the THB6064AH or Linistepper or servo drivers like the BOB PID. Compatible with MACH 3^ / 4
   
• http://www.fpga4fun.com/CNC.html A series of web page articles explaining how to calculate steps for a simple motion plan and generate the pulses via an FPGA.
• https://code.google.com/p/gocupi/ Code for Arduino and Raspberry Pi with nice acceleration curves and turn prediction. The Arduino is only there to provide precise timing for the step and direction pulse data produced by the Pi. Motion is smooth and fluid because the entrance and exit speed of each movement segment is taken into account. E.g. A 90' turn needs a full stop, but a 1' turn doesn't need to slow down at all.
• https://github.com/ErikZalm/Marlin/tree/Marlin_v1 This RepRap firmware is a mashup between Sprinter, grbl and many original parts.
• http://www.hwml.com/LeibRamp.htm LeibRamp was developed in 1994 by Aryeh Eiderman and is said to be the "World's fastest ramping (motion profile building) algorithm." On this page, Eiderman provides an overview of the math involved in calculating pulses per timer tick, for slew, and ramp acceleration / deceleration.
  http://www.hwml.com/ is an NXP LPC2136/01 based USB to 4 axis embedded motion controller in a DB25 backshell. $75 from:
  http://www.mcwidgets.com/
   
• http://read.pudn.com/downloads45/sourcecode/embed/151169/Motor.c__.htm Demo program for stepper motor control with linear ramps. Hardware: PIC18F252, L6219. The discussion of the method and the math behind it may be found here: http://fab.cba.mit.edu/classes/MIT/961.09/projects/i0/Stepper_Motor_Speed_Profile.pdf
   
• http://code.google.com/p/cnc-milling-machine/ Open source, Java G code to intermediate format, PIC firmware 2axis coordiantion with seperate Z axis movement. No acceleration.
   
• http://www.planet-cnc.com/index.asp?page=diy G code to propriatary format in PC software $100 then by USB to 4 axis motion control hardware $15 for the PIC chip, $15 for the PCB and about $15 shipping. The PIC firmware does NOT actually process G code.
   
• http://forums.reprap.org/read.php?12,9459 Arduino G code to stepper. See user.cpp file.
   
• https://github.com/simen/grbl Grbl is a free, open source, high performance CNC milling controller written in optimized C that will run on a straight Arduino
  https://www.synthetos.com/webstore/index.php/assembled-electronics/grblshield-grbl-arduino-diy-cnc-shield.html a shield is available
   
• http://pleasantsoftware.com/developer/3d/pleasant-mill/ Another mill with firmware based on the reprap.
   
• http://www.cnczone.com/forums/open_source_controller_boards/59461-full_cnc_controller.html
  http://www.usinages.com/controleur-autonome-de-cnc-t2415-75.html
  MicroBasic pic18f4620, SD-MMC card, KS0108 graphic LCD. Direct G code to movement. Bugs in circles but can be avoided. Clunky source.
   
• http://www.roboticsguy.com/projects/build-a-cheap-diy-cnc-machine Very simple design that works for drilling.
   
• http://reprap.soup.io/post/135633178/Smooth-Trajectory-in-CNC-and-3D-Printing Some notes about smoothing motion.