#LyX 1.3 created this file. For more info see http://www.lyx.org/
\lyxformat 221
\textclass book
\begin_preamble
\usepackage[plainpages=false,pdfpagelabels,colorlinks=true,linkcolor=blue]{hyperref}
\end_preamble
\language english
\inputencoding default
\fontscheme bookman
\graphics default
\float_placement !htbp
\paperfontsize default
\spacing single 
\papersize letterpaper
\paperpackage a4
\use_geometry 1
\use_amsmath 0
\use_natbib 0
\use_numerical_citations 0
\paperorientation portrait
\leftmargin 1in
\topmargin 1in
\rightmargin 0.8in
\bottommargin 0.8in
\secnumdepth 1
\tocdepth 5
\paragraph_separation skip
\defskip smallskip
\quotes_language english
\quotes_times 2
\papercolumns 1
\papersides 1
\paperpagestyle default

\layout Chapter

Basic configurations for a stepper based system
\layout Section


\begin_inset LatexCommand \label{sec:Introduction}

\end_inset 

Introduction
\layout Standard

This chapter describes some of the more common settings that users want
 to change when setting up EMC2.
 Because of the various possibilities of configuring EMC2, it is very hard
 to document them all, and keep this document relatively short.
 
\layout Standard

The most common EMC2 usage (as reported by our users) is for stepper based
 systems.
 These systems are using stepper motors with drives that accept step & direction
 signals.
 
\layout Standard

It is one of the simpler setups, because the motors run open-loop (no feedback
 comes back from the motors), yet the system needs to be configured properly
 so the motors don't stall or lose steps.
\layout Standard

Most of this chapter is based on the sample config released along with EMC2.
 The config is called stepper
\begin_inset LatexCommand \index{stepper}

\end_inset 

, and usually it is found in 
\family typewriter 
/etc/emc2/sample-configs/stepper
\family default 
.
\layout Section


\begin_inset LatexCommand \label{sec:Maximum-step-rate}

\end_inset 

Maximum step rate
\begin_inset LatexCommand \index{step rate}

\end_inset 


\layout Standard

With software step generation, the maximum step rate is one step per two
 BASE_PERIODs for step-and-direction output.
 The maximum requested step rate is the product of an axis's MAX_VELOCITY
 and its INPUT_SCALE.
 If the requested step rate is not attainable, following errors will occur,
 particularly during fast jogs and G0 moves.
\layout Standard

If your stepper driver can accept quadrature input, use this mode.
 With a quadrature signal, one step is possible for each BASE_PERIOD, doubling
 the maximum step rate.
\layout Standard

The other remedies are to decrease one or more of: the BASE_PERIOD (setting
 this too low will cause the machine to become unresponsive or even lock
 up), the INPUT_SCALE (if you can select different step sizes on your stepper
 driver, change pulley ratios, or leadscrew pitch), or the MAX_VELOCITY
 and STEPGEN_MAXVEL.
\layout Standard

If no valid combination of BASE_PERIOD, INPUT_SCALE, and MAX_VELOCITY is
 acceptable, then hardware step generation (such as with the emc2-supported
 Universal Stepper Controller)
\layout Section


\begin_inset LatexCommand \label{sec:Pinout}

\end_inset 

Pinout
\begin_inset LatexCommand \index{pinout}

\end_inset 


\layout Standard

One of the majour flaws in EMC was that you couldn't specify the pinout
 without recompiling the source code.
 EMC2 is far more flexible, and now (thanks to the Hardware Abstraction
 Layer) you can easily specify which signal goes where.
 (read the 
\begin_inset LatexCommand \ref{sec:What-is-HAL?}

\end_inset 

 section for more information about the HAL
\begin_inset LatexCommand \index{HAL}

\end_inset 

).
\layout Standard

As it is described in the HAL Introduction and tutorial, we have signals,
 pins and parameters inside the HAL.
 
\layout Standard

The ones relevant for our pinout are
\begin_inset Foot
collapsed true

\layout Standard

Note: we are only presenting one axis to keep it short, all others are similar.
\end_inset 

:
\layout LyX-Code

signals: Xstep, Xdir & Xen
\newline 
pins: parport.0.pin-XX-out & parport.0.pin-XX-in 
\begin_inset Foot
collapsed true

\layout Standard

Refer to section 
\begin_inset LatexCommand \ref{sec:Parport}

\end_inset 

 for additional information
\end_inset 


\layout Standard

Depending on what you have chosen in your ini file you are using either
 standard_pinout.hal or xylotex_pinout.hal.
 These are two files that instruct the HAL how to link the various signals
 & pins.
 Furtheron we'll investigate the standard_pinout.hal.
\layout Subsection


\begin_inset LatexCommand \label{sub:standard_pinout.hal}

\end_inset 

standard_pinout.hal
\begin_inset LatexCommand \index{standard pinout}

\end_inset 

 
\layout Standard

This file contains several HAL commands, and usually looks like this:
\layout LyX-Code


\begin_inset Include \verbatiminput{../../../configs/stepper/standard_pinout.hal}
preview false

\end_inset 


\layout Standard

The files starting with '#' are comments, and their only purpose is to guide
 the reader through the file.
\layout Subsection


\begin_inset LatexCommand \label{sub:Overview-standard_pinout.hal}

\end_inset 

Overview of the standard_pinout.hal
\layout Standard

There are a couple of operations that get executed when the standard_pinout.hal
 gets executed / interpreted:
\layout Enumerate

The Parport driver gets loaded (see 
\begin_inset LatexCommand \ref{sec:Parport}

\end_inset 

 for details)
\layout Enumerate

The read & write functions of the parport driver get assigned to the Base
 thread 
\begin_inset Foot
collapsed true

\layout Standard

the fastest thread in the EMC2 setup, usually the code gets executed every
 few microseconds
\end_inset 


\layout Enumerate

The step & direction signals for axes X,Y,Z get linked to pins on the parport
\layout Enumerate

Further IO signals get connected (estop loopback, toolchanger loopback)
\layout Enumerate

A spindle On signal gets defined and linked to a parport pin
\layout Subsection


\begin_inset LatexCommand \label{sub:Changing-standard_pinout.hal}

\end_inset 

Changing the standard_pinout.hal
\layout Standard

If you want to change the standard_pinout.hal file, all you need is a text
 editor.
 Open the file and locate the parts you want to change.
 
\layout Standard

If you want for example to change the pin for the X-axis Step & Directions
 signals, all you need to do is to change the number in the 'parport.0.pin-XX-out'
 name:
\layout LyX-Code

linksp Xstep parport.0.pin-03-out 
\newline 
linksp Xdir  parport.0.pin-02-out
\layout Standard

can be changed to:
\layout LyX-Code

linksp Xstep parport.0.pin-02-out 
\newline 
linksp Xdir  parport.0.pin-03-out
\layout Standard

or basicly any other numbers you like.
 
\layout Standard

Hint: make sure you don't have more than one signal connected to the same
 pin.
\layout Subsection


\begin_inset LatexCommand \label{sub:Changing-the-polarity}

\end_inset 

Changing the polarity of a signal
\begin_inset LatexCommand \index{signal polarity}

\end_inset 


\layout Standard

If external hardware expects an 
\begin_inset Quotes eld
\end_inset 

active low
\begin_inset Quotes erd
\end_inset 

 signal, set the corresponding 
\family typewriter 
-invert
\family default 
 parameter.
 For instance, to invert the spindle control signal:
\layout LyX-Code

setp parport.0.pin-09-invert TRUE
\layout Subsection


\begin_inset LatexCommand \label{sub:PWM-Spindle-Speed}

\end_inset 

Adding PWM Spindle Speed Control
\begin_inset LatexCommand \index{spindle speed control}

\end_inset 


\layout Standard

If your spindle can be controlled by a PWM signal, use the 
\family typewriter 
pwmgen
\family default 
 component to create the signal:
\layout LyX-Code

loadrt pwmgen output_type=0
\newline 
addf pwmgen.update servo-thread
\newline 
addf pwmgen.make-pulses base-thread
\newline 
net spindle-speed-cmd motion.spindle-speed-out => pwmgen.0.value
\newline 
net spindle-on motion.spindle-on => pwmgen.0.enable
\newline 
net spindle-pwm pwmgen.0.pwm => parport.0.pin-09-out
\newline 
setp pwmgen.0.scale 1800 # Change to your spindle's top speed in RPM
\layout Standard

This assumes that the spindle controller's response to PWM is simple: 0%
 PWM gives 0RPM, 10% PWM gives 180 RPM, etc.
 If there is a minimum PWM required to get the spindle to turn, follow the
 example in the 
\emph on 
nist-lathe
\emph default 
 sample configuration to use a 
\family typewriter 
scale
\family default 
 component.
\layout Subsection


\begin_inset LatexCommand \label{sub:Adding-enable-signal}

\end_inset 

Adding an enable signal
\begin_inset LatexCommand \index{enable signal}

\end_inset 


\layout Standard

Some amplifiers (drives) require an enable signal before they accept and
 command movement of the motors.
 For this reason there are already defined signals called 'Xen', 'Yen',
 'Zen'.
\layout Standard

To connect them use the following example:
\layout LyX-Code

linksp Xen parport.0.pin-08-out
\layout Standard

You can either have one single pin that enables all drives, or several,
 depending on the setup you have.
 Note however that usually when one axis faults, all the other ones will
 be disabled aswell, so having only one signal / pin is perfectly safe.
\layout Subsection

Adding an external ESTOP
\begin_inset LatexCommand \index{ESTOP}

\end_inset 

 button
\layout Standard

As you can see in 
\begin_inset LatexCommand \ref{sub:standard_pinout.hal}

\end_inset 

 by default the stepper configuration assumes no external ESTOP button.
 
\begin_inset Foot
collapsed true

\layout Standard

An extensive explanation of hooking up ESTOP circuitry is explained in the
 wiki.linuxcnc.org and in the Integrator Manual
\end_inset 


\layout Standard

To add a simple external button you need to replace the line:
\layout LyX-Code

linkpp iocontrol.0.user-enable-out iocontrol.0.emc-enable-in
\layout Standard

with
\layout LyX-Code

linkpp parport.0.pin-01-in iocontrol.0.emc-enable-in
\layout Standard

This assumes an ESTOP switch connected to pin 01 on the parport.
 As long as the switch will stay pushed
\begin_inset Foot
collapsed true

\layout Standard

make sure you use a maintained switch for ESTOP.
\end_inset 

, EMC2 will be in the ESTOP state.
 When the external button gets released EMC2 will imediately switch to the
 ESTOP-RESET state, and all you need to do is switch to Machine On
\begin_inset LatexCommand \index{machine on}

\end_inset 

 and you'll be able to continue your work with EMC2.
\the_end