Manuel dos Santos, Ricardo Loureiro, Helmut Dispert

Fachbereich Informatik und Elektrotechnik
Title
Programming
CAN-based Fieldbus Systems using Java
Manuel Joaquim Pereira dos Santos,
Ricardo José Caetano Loureiro
Universidade de Aveiro, Aveiro, Portugal,
Helmut Dispert
Department of Computer Science and Electrical
Engineering,
Kiel University of Applied Sciences, Kiel, Germany
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Contents
1. Introduction:
Embedded Intelligent Devices
2. Java in Embedded Control:
e.g.: Java Servlet Technology (the Embedded
Java Controller - EJC)
3. Java and Native Code
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Evolution
The evolution of embedded intelligent devices is
driven by technological advancements:
Ø low cost microprocessors and peripheral
devices
Ø Internet
Ø Java programming language
Examples:
Ø new hardware platforms (e.g. Strong ARM
architecture)
Ø Internet and the HTTP to access devices
Ø Development of robust and reliable software
using Java.
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Opportunities
Sun Microsystems, Inc.:
"Combining the strengths of these (new)
technologies, there is a huge market opportunity
for companies that discover how to leverage the
benefits of Java technology on embedded
devices."
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java
Solution:
A New Paradigm:
Write once, run anywhere
Java
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Fachbereich Informatik und Elektrotechnik
Java
History of Java (true story)
Ø 1990:
A small group is formed at Sun Microsystems with
the task to think about the future of multimedia in
private households.
Group Member: James Gosling
Ø Idea:
develop a generic and simple programming
language to implement intelligent electronic
devices (household).
⇒
Embedded Programming
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java
Why Java?
Ø Object-oriented
(encapsulation, polymorphism, inheritance),
Ø No multiple inheritance,
Ø Platform independent bytecode,
Ø Java primitive data types have fixed sizes,
Ø Automatic run-time bounds-checking,
Ø True Boolean type,
Ø No pointer programming,
Ø Automatic garbage collection,
Ø Language support for multithreaded applications.
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java in Embedded Systems
Java Usage Models:
The proposed Java usage models fall into one of
four categories:
Ø No Java
Ø Embedded Web Server Java
Ø Embedded Applet Java
Ø Application Java
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java in Embedded Systems
These models are distinguished by two binary
variables:
Ø location of the stored Java bytecodes
Ø the processor on which the bytecodes are
executed
These variables can take one of two values:
Ø target (the embedded system)
Ø host (a general-purpose computer attached to
the embedded system)
Ref.: Michael Barr
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java in Embedded Systems
Host
Host
Java
Target
Host
Host
Java
Target
Target
Target
Java
No Java
Embedded
Web Server
Java
Embedded
Applet
Application
Ref.: Michael Barr
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java 2 Platform
Profile
Profile Profile
Profile
Profile
Profile Profile
Profile
Java
Java22
Enterprise
Enterprise
Edition
Edition
(J2EE)
(J2EE)
Core
CoreAPIs
APIs
Java
Java22
Standard
Standard
Edition
Edition
(J2SE)
(J2SE)
Core
CoreAPIs
APIs
Java 2 Platform, Micro Edition
(J2ME) encompasses VMs and core
APIs specified via Configurations as
well as vertical – or market-specific
APIs specified in Profiles.
TV
TV
Profile
Profile
Screen
Screen Car
Car
Phone
Phone Profile
Profile
Profile
Profile
Personal
Personal
Profile
Profile
Mobile Information
Mobile
DeviceInformation
Profile
Device Profile
Java
Java22Micro
MicroEdition
EditionCore
CoreAPIs
APIs
Smart
Smart
Card
Card
Profile
Profile
Java
JavaProgramming
ProgrammingLanguage
Language
Java
JavaHotSpot
HotSpot
Java
JavaVirtual
VirtualMaschine
Maschine(JVM)
(JVM)
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KVM
KVM
Card
CardVM
VM
Fachbereich Informatik und Elektrotechnik
Java Application Environments
Desktop OS
Enterprise Servers
Mainframes
Java
AE
RTOS Vendors
Set-top boxes
PDAs
ScreenPhones
Hi-end mobile phones
Internet TV
Industrial Controllers
Car navigation
Intrumentation
Automotive
Printers
Hi-end Pagers
Mid-range Phones
Personal
Java
AE
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SmartCards
Java Ring
Embedded
Java
AE
Java
Card
Fachbereich Informatik und Elektrotechnik
Java 2 Platform Editions
JavaCard
Java Technology
Enabled Devices
Micro
Edition
Java Technology
Enabled Desktop
Standard
Edition
Embedded Internet, © Prof. Dr. Helmut Dispert
Workgroup
Server
High-End
Server
Enterprise
Edition
Fachbereich Informatik und Elektrotechnik
Java
Application Portability:
1. mechanism for executing Java bytecodes on
any processor
2. common set of class libraries
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java Development Cycle
Compile-time
Environment
Run-Time Environment
(Java Platform)Environment
Java
Source
(.java)
Class Loader
Bytecode Verifier
Java
Compiler
Java
Bytecode
(.class)
Java
Interpreter
Just-in-Time
Compiler
Run-Time System
Operating System
Hardware
Embedded Internet, © Prof. Dr. Helmut Dispert
Java Classes
Libraries
Virtual
Java Machine
VM
Fachbereich Informatik und Elektrotechnik
Java Architecture
Java Programming
Language
The Java Architecture
1. Programming Language
2. Virtual Machine (VM)
3. API
Compiled Byte Code
Java Runtime System
Virtual
Machine
Java
API
Operating System
Computer Hardware
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Access Hardware using Java
The basic idea of embedded control is to directly
access hardware level properties:
Ø Registers, I/O-interfaces, sensors, actuators,
etc.
Problem à Basic Properties of Java:
Ø Platform independent bytecode,
Ø No pointer programming,
Ø Automatic garbage collection,
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Access Hardware using Java
Solutions:
Ø Use dedicated hardware platform, dedicated
OS and dedicated Java VM.
Example:
Snijder Embedded Java Controller (EJC).
see: 1st Int. Workshop, Vaasa, 2002
Ø Use native languages that allow access to
hardware level functions.
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java - Jbed
VM
Glue Code
VM
Browser
Glue Code
VM
Glue Code
OS
RTOS
OS
and
VM
OS
Hardware
Hardware
Hardware
Hardware
Java in a
WWW
browser
Java on a
desktop
OS
Java on a
RTOS
Java on the
bare
metal
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
I2C
RS485
RS485
COM 1 (RS232)
COM 1
COM 0 (TTL)
COM 0
Ethernet
ETH.
PWR
EJC
Digital
I/O
LCD
1-Wire
Digital I/O
LCD
1-Wire
Switch Input
LED Output
EJC-SK1 carrier board block diagram
Embedded Internet, © Prof. Dr. Helmut Dispert
Boot Flash
I2C
System Bus
EJC - Embedded Java Controller
Boot Flash
Fachbereich Informatik und Elektrotechnik
EJC - EW1A block diagram
E2PROM
DRAM
CPU
ARM7TDMI
Temp.
Sensor
Flash
ISA-like +
memory
bus
COM 1
TTL
COM 2
RS232
RS485
I2C
master
Digital
I/O
LCD
DIMM connector
Embedded Java Controller block diagram
Embedded Internet, © Prof. Dr. Helmut Dispert
Ethern.
Fachbereich Informatik und Elektrotechnik
EJC
Java
Level
JVM
Kernel
Drivers
•••
User applications
and servlets
HTTP
server
FTP
server
Telnet
server
EJC class library + servlet framework
Intent JVM + PJAE + javax.comm
EJC middleware and
system software
Elate RTOS kernel + low-level libraries
(TCP/IP, file system architecture, graphic subsystem, etc.)
Serial Ethernet
I2 C
Dig I/O Flash NV RAM • • •
LCD
Overview of the EJC software architecture.
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
EJC - Native Code
Access to hardware or peripherals through
native code:
Special feature of the EJC (the intent JVM):
Java classes can be directly written in VP assembler. VP
assembler is a high-level assembler language which is
targeted at a special Virtual Processor, and that is
translated to native code either statically, at sysgen-time,
or dynamically, when a class is loaded by the device
(happens automatically).
⇒ Access to hardware is possible without the runtime
overhead of JNI or other similar mechanisms.
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI
JNI - The Java Native Interface
Advantages:
Ø Support platform-dependent features.
Ø Integration: Make existing libraries or
applications written in another programming
language available to Java.
Ø Speed: Implement time-critical code.
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI
Application
C Side
Java Side
Exceptions
Functions
JNI
Classes
Libraries
VM
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI
JNI allows interaction in two directions:
Ø Java programs can use native methods
written in other languages
Ø Native methods can use Java objects and
methods out of Java applications
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI
Java Libraries
C Program
Java Classes
Java VM
Embedded Internet, © Prof. Dr. Helmut Dispert
Java Methods
Fachbereich Informatik und Elektrotechnik
JNI
C Routines
Assembly Rout.
Java Program
C++ Classes
Exception Handler
C Debugger
C Runtime
TypeChecker
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI-Example
Java-File: HelloWorld.java
class HelloWorld
{
public native void displayHelloWorld();
static
{
System.loadLibrary("hello");
}
public static void main(String[] args)
{
new HelloWorld().displayHelloWorld();
}
}
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI-Example
Java Code Compilation:
javac HelloWorld.java
Creating the C header file:
javah –jni HelloWorld
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI-Example
Name of native language function that
implements the native methods:
prefix + class name + _ +
â
â
â
method name
â
java_ + HelloWorld + _ + displayHelloWorld
JNIEXPORT void JNICALL
Java_HelloWorld_displayHelloWorld(JNIEnv *, jobject);
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI-Example
Native Methods (C code):
#include <jni.h>
#include "HelloWorld.h“
#include <stdio.h>
JNIEXPORT void JNICALL
Java_HelloWorld_displayHelloWorld
(JNIEnv *env, jobject obj)
{
printf("Hello World!\n");
return;
}
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI-Example
HelloWorldImp.c contains three header files:
1.jni.h
This file contains information needed by the
native language to exchange data with the
Java runtime system.
2.HelloWorld.h
The generated header file.
3.stdio.h
Contains the printf function.
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
JNI-Example
1.
Write Java Code
4.
Write implementation
of native method
jni.h
stdio.h
HelloWorld.java
HelloWorldImp.c
2.
Compile with javac
5.
Compile native code,
load shared library
HelloWorld.class
hello.dll
3.
Generate header file
with javah
HelloWorld.h
Embedded Internet, © Prof. Dr. Helmut Dispert
6.
Run program using
java interpreter
"Hello World"
Fachbereich Informatik und Elektrotechnik
Java in Embedded Systems
Why Embedded Java?
Ø Hardware Independence (greater than with C/C++)
Ø Downloading capabilities:
Software downloaded into device
Ø Internet Connectivity
Ø Security
Ø Better Productivity
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Application: CAN-Bus
CAN-Bus ⇒ Controller Area Network
Serial 2-wire bus system
aimed at autombile applications,
developed by Bosch.
International Standard (ISO 11898)
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Field Bus Systems
Field Bus Organizations
Field Bus Systems
Sensor/Actuator Bus
ASI
INTERBUS-S
PROFIBUS DP
Process Bus
CAN
Embedded Internet, © Prof. Dr. Helmut Dispert
DIN-Bus
BITBUS
PROFIBUS FMS
P-NET
Fachbereich Informatik und Elektrotechnik
Field Bus Systems
Virtual CAN Interface
Control
Functions
Monitor
Functions
CAN
Analyzer
User
Application
Virtual CAN Interface
PCI-card
Port
Adapter
USB-CAN
CAN
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java based CAN Program
class: VCIJNI.java
**
Function: VCI2_PrepareBoard
**
Native method declaration
public native int VCI2_PrepareBoard(CAN_Analyser myApp,
int board_type,
short board_no,
String AddInfo,
byte AddInfoLength,
JCallback receive,
byte [] m_callback_databytes);
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Dynamic Link Libraries
Operating System
Code in class VCIJNI.java
to load DLL (VCIJNI.dll)
into memory
**
**
Windows
.dll
Unix
.so
Mac OS X
.dylib
JNI-function
for loading of the VCIJNI.DLL
static {
System.loadLibrary("VCIJNI");
}
public VCIJNI() {
}
Embedded Internet, © Prof. Dr. Helmut Dispert
Extension
Fachbereich Informatik und Elektrotechnik
Dynamic Link Libraries
Java Code Compilation:
javac VCIJNI.java
Creating the C header file:
javah –jni VCIJNI
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Fachbereich Informatik und Elektrotechnik
Dynamic Link Libraries
Generated Header File IXXAT_VCIJNI.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class IXXAT_VCIJNI */
#ifndef _Included_IXXAT_VCIJNI
#define _Included_IXXAT_VCIJNI
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class:
IXXAT_VCIJNI
* Method:
VCI2_PrepareBoard
* Signature:
(LIXXAT/CAN_Analyser;ISLjava/lang/String;BLIXXAT/JCallback;[B)I
*/
JNIEXPORT jint JNICALL Java_IXXAT_VCIJNI_VCI2_1PrepareBoard
JNIEnv *, jobject, jobject, jint, jshort, jstring, jbyte,
jobject, jbyteArray);
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Dynamic Link Libraries
File VCIJNI.cpp implementeing the native code
for function
Java_IXXAT_VCIJNI_VCI2_1PrepareBoard
JNIEXPORT jint JNICALL Java_IXXAT_VCIJNI_VCI2_1PrepareBoard
(
JNIEnv * env,
jobject jObj,
jobject myApp,
jint board_type,
jshort board_no,
jstring AddInfo,
jbyte AddInfoLength,
jobject JReceiveCallback,
jbyteArray callback_databytes)
{
int i_test;
jboolean *isCopy = NULL;
//Produce a new global reference to Object " JReceiveCallback "
g_JObj_JCallback = env->NewGlobalRef(JReceiveCallback);
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Dynamic Link Libraries
Create Object:
// Object with the Java Native Interface
static VCIJNI vci = new VCIJNI();
// prepare board for further configuration
i_test = vci.VCI2_PrepareBoard(
myApp,
BoardConfStruct.board_type,
BoardConfStruct.board_no,
AddInfo,
AddInfoLength,
JReceiveCallback,
JReceiveCallback.m_a_data);
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java/CAN - demo
a) CAN Interface:
USB-to-CAN Module
Intelligent CAN module
for the USB-Port
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java/CAN - demo
b) Connected Device:
Absolute Rotary Encoders
Allows a direct read-out
of the angular position
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Java/CAN - demo
Program Code:
CAN Code:
GUI:
Java
C++
Java Swing
Future Expansion:
Internet Connectivity: Java
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
Using Java to Control CAN
Some more important applications
CAN Bus
CAN
Device
ON
OFF
Summer Cottage
in Vaasa
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
The end
Thank you!
Embedded Internet, © Prof. Dr. Helmut Dispert
Fachbereich Informatik und Elektrotechnik
The End
Contact:
Prof. Dr. Helmut Dispert
University of Applied Sciences Kiel
Faculty of
Computer Science and Electrical Engineering
Grenzstr. 3
24149 Kiel, Germany
Tel.:
+49-431-210-4114/4123
Fax.:
+49-431-210-64114
E-Mail:
[email protected]
Embedded Internet, © Prof. Dr. Helmut Dispert