This document provides an overview of LinuxCNC, an open-source CNC controller. It discusses the basic components of a CNC system and the software workflow. It then describes how to install and build LinuxCNC from source code. The key configuration files like INI, HAL, VAR and TBL are introduced. Finally, it explains the hardware abstraction layer (HAL) which provides a way to connect LinuxCNC signals to hardware pins through components, pins, signals and functions. The HAL uses commands like loadrt, addf, loadusr and net to manage the connections.

1. LinuxCNC初探
DMP Electronics Inc.
intern 陳伯綸（中正資工OS-Lab）

2. Outline
● About CNC
● LinuxCNC：Install、Settings、compiler
● LinuxCNC Software Overview
● LinuxCNC HAL development

3. Wikipedia

4. Work Flow

5. Software Flow of NC System

6. The Progress Direction of the
CNC System

7. Download
● http://www.linuxcnc.org/index.php/english/downlo
ad

8. Install build-dev
● http://www.linuxcnc.org/hardy/dists/hardy/linuxcnc
● 2.5/source/linuxcnc_2.5.3.dsc

9. Install build-dev & Git

10. Get Source

11. Building LinuxCNC

12. Building LinuxCNC

13. Building LinuxCNC

14. Building LinuxCNC

15. Building LinuxCNC

16. Building LinuxCNC

17. Source File

18. Simple LinuxCNC
Controlled Machine

19. LinuxCNC Hierarchical

20. LinuxCNC Message Links

21. EMCTASK

22. EMCMOT

23. EMCIO

24. The Configuration Files
 INI : The ini file overrides defaults that are compiled into the
LinuxCNC code.
 HAL: The HAL files start up process modules and provide
linkages between LinuxCNC signals and specific hardware
pins.
 VAR: The var file is a way for the interpreter to save some
values from one run to the next. These values are saved from
one run to another but not always saved immediately.
 TBL:The tbl file saves tool information.
 NML: The nml file configures the communication channels
used by the LinuxCNC. It is normally setup to run all of the
communication within a single computer but can be modified
to communicate between several computers.

25. The Configuration Files
 The INI File Components
 Comments
 Sections
 Variables
 Custom Sections and Variables

26. The Configuration Files
 Hardware Abstraction Layer (HAL)
 Component
 Parameter
 Pin
 Physical_Pin
 Signal
 Type
 Function
 Thread

27. Hardware Abstraction Layer
(HAL)
 Component
 A HAL component is a piece of software with well-defined inputs, outputs,
and behavior, that can be installed and interconnected as needed.
 Parameter
 Many hardware components have adjustments that are not connected
to any other components but still need to be accessed. There are two
types of parameters: input & Output .
 Pin
 Hardware components have terminals which are used to interconnect
them. The HAL equivalent is a pin or HAL pin. HAL pins are software entities
that exist only inside the computer.
 Physical_Pin
 Many I/O devices have real physical pins or terminals that connect to
external hardware. To avoid confusion, these are referred to as physical
pins. These are the things that stick out into the real world.

28. Hardware Abstraction Layer
(HAL)
 Signal
 In a physical machine, the terminals of real hardware components are
interconnected by wires.
 Type
 Bit - a single TRUE/FALSE or ON/OFF value
 float - a 64 bit floating point value, with approximately 53 bits of resolution
and over 1000 bits of dynamic range.
 u32 - a 32 bit unsigned integer, legal values are 0 to 4,294,967,295
 s32 - a 32 bit signed integer, legal values are -2,147,483,647 to
+2,147,483,647
 Both pins and signals have types, and signals can only be connected to
pins of the same type

29. Hardware Abstraction Layer
(HAL)
 Function
 Each function is a block of code that performs a specific action. The
system integrator can use threads to schedule a series of functions to be
executed in a particular order and at specific time intervals.
 Thread
 A thread is a list of functions that runs at specific intervals as part of a
realtime task. When a thread is first created, it has a specific time interval
(period), but no functions. Functions can be added to the thread, and will
be executed in order every time the thread runs.

30. Hardware Abstraction Layer
(HAL)
 HAL Commands
 loadrt
 The command loadrt loads a real time HAL component. Real time
component functions need to be added to a thread to be updated
at the rate of the thread
 addf
 The command addf adds a real time component function to a
thread. You have to add a function from a HAL real time component
to a thread to get the function to update at the rate of the thread.

31. Hardware Abstraction Layer
(HAL)
 HAL Commands
 loadusr
 The command loadusr loads a user space HAL component. User
space programs are their own separate processes, which optionally
talk to other HAL components via pins and parameters. You cannot
load real time components into user space.
 net
 The command net creates a connection between a signal and and
one or more pins. If the signal does not exist net creates the new
signal.

32. Hardware Abstraction Layer
(HAL)
 HAL Commands
 setp
 The command setp sets the value of a pin or parameter. The valid
values will depend on the type of the pin or parameter.
 unlinkp
 The command unlinkp unlinks a pin from the connected signal. If no
signal was connected to the pin prior running the command, nothing
happens.

33. LinuxCNC HAL
development
Show me the coding

34. Thanks for your listening