Renesas 70 User Manual

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REJ10J1025-0200Z

M3T-MR308/4 V.4.00

User’s Manual

Real-time OS for M16C/70,80,M32C/80 Series

Rev.2.00 Nov 1, 2005

Active X, Microsoft, MS-DOS, Visual Basic, Visual C++, Windows and Windows NT are either registered trademarks or trademarks of Microsoft Corporation in the United States and other countries. IBM and AT are registered trademarks of International Business Machines Corporation. Intel and Pentium are registered trademarks of Intel Corporation. Adobe, Acrobat, and Acrobat Reader are trademarks of Adobe Systems Incorporated. TRON is an abbreviation of "The Real-time Operating system Nucleus." ITRON is an abbreviation of "Industrial TRON." µITRON is an abbreviation of "Micro Industrial TRON." TRON, ITRON, and µITRON do not refer to any specific product or products. All other brand and product names are trademarks, registered trademarks or service marks of their respective holders.

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Preface

The M3T-MR308/4(abbreviated as MR308) is a real-time operating system1 for the M16C/70,80, M32C/80 series microcomputers. The MR308 conforms to the µITRON Specification. This manual describes the procedures and precautions to observe when you use the MR308 for programming purposes. For the detailed information on individual service call procedures, refer to the MR308 Reference Manual.

Requirements for MR308 Use

When creating programs based on the MR308, it is necessary to purchase the following product of Renesas.

• C-compiler package M3T-NC308WA(abbreviated as NC308) for M16C/70,80 M32C/80 series micro-

computers

Document List

The following sets of documents are supplied with the MR308.

• Release Note

Presents a software overview and describes the corrections to the Users Manual and Reference Manual.

• Users Manual (PDF file)

Describes the procedures and precautions to observe when using the MR308 for programming purposes.

• Reference Manual (PDF file)

Describes the MR308 service call procedures and typical usage examples.

Please read the release note before reading this manual.

Right of Software Use

The right of software use conforms to the software license agreement. You can use the MR308 for your product development purposes only, and are not allowed to use it for the other purposes. You should also note that this manual does not guarantee or permit the exercise of the right of software use.

Hereinafter abbreviated "real-time OS"

µITRON4.0 Specification is the open real-time kernel specification upon which the TRON association decided

The specification document of µITRON4.0 specification can come to hand from a TRON association homepage

(http://www.assoc.tron.org/).

The copyright of µITRON4.0 specification belongs to the TRON association.

Contents

Chapter 1 User’s Manual Organization ....................................................................................................- 1 -

Chapter 2 General Information ................................................................................................................. - 3 -

2.1 Objective of MR308 Development...................................................................................................... - 4 -

2.2 Relationship between TRON Specification and MR308................................................................... - 6 -

2.3 MR308 Features .................................................................................................................................- 7 -

Chapter 3 Introduction to MR308..............................................................................................................- 9 -

3.1 Concept of Real-time OS ..................................................................................................................- 10 -

3.1.1 Why Real-time OS is Necessary ............................................................................................... - 10 -

3.1.2 Operating Principles of Real-time OS...................................................................................... - 13 -

3.2 Service Call ....................................................................................................................................... - 16 -

3.2.1 Service Call Processing ............................................................................................................. - 17 -

3.2.2 Task Designation in Service call ..............................................................................................- 18 -

3.3 Task ................................................................................................................................................... - 19 -

3.3.1 Task Status................................................................................................................................ - 19 -

3.3.2 Task Priority and Ready Queue ............................................................................................... - 23 -

3.3.3 Task Priority and Waiting Queue............................................................................................. - 24 -

3.3.4 Task Control Block(TCB) .......................................................................................................... - 25 -

3.4 System States.................................................................................................................................... - 27 -

3.4.1 Task Context and Non-task Context........................................................................................ - 27 -

3.4.2 Dispatch Enabled/Disabled States ........................................................................................... - 28 -

3.4.3 CPU Locked/Unlocked States ................................................................................................... - 29 -

3.4.4 Dispatch Disabled and CPU Locked States............................................................................. - 29 -

3.5 MR308 Kernel Structure.................................................................................................................. - 30 -

3.5.1 Module Structure....................................................................................................................... - 30 -

3.5.2 Module Overview....................................................................................................................... - 31 -

3.5.3 Task Management Function..................................................................................................... - 32 -

3.5.4 Synchronization functions attached to task ............................................................................- 34 -

3.5.5 Synchronization and Communication Function (Semaphore)................................................ - 37 -

3.5.6 Synchronization and Communication Function (Eventflag) .................................................. - 39 -

3.5.7 Synchronization and Communication Function (Data Queue) .............................................. - 41 -

3.5.8 Synchronization and Communication Function (Mailbox) ..................................................... - 42 -

3.5.9 Memory pool Management Function ....................................................................................... - 44 -

Fixed-size Memory pool Management Function ................................................................................................. - 44 -

Variable-size Memory Pool Management Function............................................................................................. - 45 -

3.5.10 Time Management Function..................................................................................................... - 47 -

3.5.11 Cyclic Handler Function ........................................................................................................... - 49 -

3.5.12 Alarm Handler Function........................................................................................................... - 50 -

3.5.13 System Status Management Function..................................................................................... - 51 -

3.5.14 Interrupt Management Function .............................................................................................- 52 -

3.5.15 System Configuration Management Function ........................................................................ - 53 -

3.5.16 Extended Function (Short Data Queue) .................................................................................. - 53 -

3.5.17 Extended Function (Reset Function) ....................................................................................... - 54 -

3.5.18 Service calls That Can Be Issued from Task and Handler..................................................... - 55 -

Chapter 4 Applications Development Procedure Overview.................................................................... - 59 -

4.1 Overview............................................................................................................................................ - 60 -

4.2 Development Procedure Example.................................................................................................... - 62 -

4.2.1 Applications Program Coding................................................................................................... - 62 -

4.2.2 Configuration File Preparation ................................................................................................ - 64 -

4.2.3 Configurator Execution............................................................................................................. - 65 -

4.2.4 System generation..................................................................................................................... - 65 -

4.2.5 Writing ROM..............................................................................................................................- 65 -

Chapter 5 Detailed Applications.............................................................................................................. - 67 -

5.1 Program Coding Procedure in C Language..................................................................................... - 68 -

5.1.1 Task Description Procedure...................................................................................................... - 68 -

5.1.2 Writing a Kernel (OS Dependent) Interrupt Handler ............................................................ - 70 -

5.1.3 Writing Non-kernel (OS-independent ) Interrupt Handler .................................................... - 71 -

5.1.4 Writing Cyclic Handler/Alarm Handler................................................................................... - 72 -

5.2 Program Coding Procedure in Assembly Language ....................................................................... - 73 -

5.2.1 Writing Task .............................................................................................................................. - 73 -

5.2.2 Writing Kernel(OS-dependent) Interrupt Handler................................................................. - 75 -

5.2.3 Writing Non-kernel(OS-independent) Interrupt Handler ...................................................... - 76 -

5.2.4 Writing Cyclic Handler/Alarm Handler................................................................................... - 77 -

5.3 The Use of INT Instruction.............................................................................................................. - 78 -

5.4 The Use of registers of bank ............................................................................................................ - 78 -

5.5 Regarding Interrupts........................................................................................................................ - 79 -

5.5.1 Types of Interrupt Handlers..................................................................................................... - 79 -

5.5.2 The Use of Non-maskable Interrupt ........................................................................................- 79 -

5.5.3 Controlling Interrupts............................................................................................................... - 80 -

5.6 Regarding Delay Dispatching .......................................................................................................... - 82 -

5.7 Regarding Initially Activated Task..................................................................................................- 83 -

5.8 Modifying MR308 Startup Program................................................................................................ - 84 -

5.8.1 C Language Startup Program (crt0mr.a30)............................................................................. - 85 -

5.9 Memory Allocation............................................................................................................................ - 90 -

5.9.1 Section Allocation of start.a30 .................................................................................................. - 91 -

5.9.2 Section Allocation of crt0mr.a30............................................................................................... - 92 -

5.10 Using in M16C/70 Series.................................................................................................................. - 94 -

Chapter 6 Using Configurator ................................................................................................................. - 95 -

6.1 Configuration File Creation Procedure ........................................................................................... - 96 -

6.1.1 Configuration File Data Entry Format.................................................................................... - 96 -

Operator ................................................................................................................................................................ - 97 -

Direction of computation ...................................................................................................................................... - 97 -

6.1.2 Configuration File Definition Items......................................................................................... - 99 -

[( System Definition Procedure )]......................................................................................................................... - 99 -

[( System Clock Definition Procedure )]............................................................................................................. - 101 -

[( Definition respective maximum numbers of items )]..................................................................................... - 102 -

[( Task definition )].............................................................................................................................................. - 104 -

[( Eventflag definition )] ..................................................................................................................................... - 106 -

[( Semaphore definition )]................................................................................................................................... - 107 -

[(Data queue definition )] ................................................................................................................................... - 108 -

[( Short data queue definition )]......................................................................................................................... - 109 -

[( Mailbox definition )] .........................................................................................................................................- 110 -

[( Fixed-size memory pool definition )]................................................................................................................- 111 -

[( Variable-size memory pool definition )] ...........................................................................................................- 112 -

[( Cyclic handler definition )]...............................................................................................................................- 113 -

[( Alarm handler definition )] ..............................................................................................................................- 115 -

[( Interrupt vector definition )]............................................................................................................................- 116 -

6.1.3 Configuration File Example.................................................................................................... - 119 -

6.2 Configurator Execution Procedures .............................................................................................. - 123 -

6.2.1 Configurator Overview............................................................................................................ - 123 -

6.2.2 Setting Configurator Environment ........................................................................................ - 125 -

6.2.3 Configurator Start Procedure................................................................................................. - 126 -

6.2.4 makefile generate Function .................................................................................................... - 127 -

6.2.5 Precautions on Executing Configurator................................................................................. - 128 -

6.2.6 Configurator Error Indications and Remedies ...................................................................... - 129 -

Error messages ................................................................................................................................................... - 129 -

Warning messages .............................................................................................................................................. - 131 -

Other messages................................................................................................................................................... - 131 -

6.3 Editing makefile .............................................................................................................................- 132 -

6.4 About an error when you execute make ........................................................................................ - 133 -

Chapter 7 Application Creation Guide .................................................................................................. - 135 -

7.1 Processing Procedures for System Calls from Handlers.............................................................. - 136 -

7.1.1 System Calls from a Handler That Caused an Interrupt during Task Execution .............. - 137 -

7.1.2 System Calls from a Handler That Caused an Interrupt during System Call Processing.- 138 -

7.1.3 System Calls from a Handler That Caused an Interrupt during Handler Execution........ - 139 -

7.2 Stacks .............................................................................................................................................. - 140 -

7.2.1 System Stack and User Stack................................................................................................. - 140 -

Chapter 8 Sample Program Description................................................................................................ - 141 -

8.1 Overview of Sample Program ........................................................................................................- 142 -

8.2 Program Source Listing.................................................................................................................. - 143 -

8.3 Configuration File........................................................................................................................... - 144 -

Chapter 9 Separate ROMs ..................................................................................................................... - 145 -

9.1 How to Form Separate ROMs........................................................................................................ - 146 -

iii

List of Figures

Figure 3.1 Relationship between Program Size and Development Period...................................- 10 -

Figure 3.2 Microcomputer-based System Example(Audio Equipment) .......................................- 11 -

Figure 3.3 Example System Configuration with Real-time OS(Audio Equipment) ....................- 12 -

Figure 3.4 Time-division Task Operation .......................................................................................- 13 -

Figure 3.5 Task Execution Interruption and Resumption ............................................................- 13 -

Figure 3.6 Task Switching...............................................................................................................- 14 -

Figure 3.7 Task Register Area.........................................................................................................- 15 -

Figure 3.8 Actual Register and Stack Area Management .............................................................- 15 -

Figure 3.9 Service call......................................................................................................................- 16 -

Figure 3.10 Service Call Processing Flowchart..............................................................................- 17 -

Figure 3.11 Task Identification .......................................................................................................- 18 -

Figure 3.12 Task Status...................................................................................................................- 19 -

Figure 3.13 MR308 Task Status Transition...................................................................................- 20 -

Figure 3.14 Ready Queue (Execution Queue) ................................................................................- 23 -

Figure 3.15 Waiting queue of the TA_TPRI attribute ...................................................................- 24 -

Figure 3.16 Waiting queue of the TA_TFIFO attribute.................................................................- 24 -

Figure 3.17 Task control block ........................................................................................................- 26 -

Figure 3.18 Cyclic Handler/Alarm Handler Activation .................................................................- 28 -

Figure 3.19 MR308 Structure..........................................................................................................- 30 -

Figure 3.20 Task Resetting..............................................................................................................- 32 -

Figure 3.21 Alteration of task priority............................................................................................- 33 -

Figure 3.22 Task rearrangement in a waiting queue ....................................................................- 33 -

Figure 3.23 Wakeup Request Storage.............................................................................................- 34 -

Figure 3.24 Wakeup Request Cancellation.....................................................................................- 34 -

Figure 3.25 Forcible wait of a task and resume.............................................................................- 35 -

Figure 3.26 Forcible wait of a task and forcible resume................................................................- 35 -

Figure 3.27 dly_tsk service call .......................................................................................................- 36 -

Figure 3.28 Exclusive Control by Semaphore ................................................................................- 37 -

Figure 3.29 Semaphore Counter .....................................................................................................- 37 -

Figure 3.30 Task Execution Control by Semaphore.......................................................................- 38 -

Figure 3.31 Task Execution Control by the Eventflag...................................................................- 40 -

Figure 3.32 Data queue ...................................................................................................................- 41 -

Figure 3.33 Mailbox .........................................................................................................................- 42 -

Figure 3.34 Message queue .............................................................................................................- 43 -

Figure 3.35 Memory Pool Management..........................................................................................- 44 -

Figure 3.36 pget_mpl processing.....................................................................................................- 46 -

Figure 3.37 rel_mpl processing .......................................................................................................- 46 -

Figure 3.38 Timeout Processing......................................................................................................- 47 -

Figure 3.39 Cyclic handler operation in cases where the activation phase is saved ...................- 49 -

Figure 3.40 Cyclic handler operation in cases where the activation phase is not saved.............- 49 -

Figure 3.41 Typical operation of the alarm handler ......................................................................- 50 -

Figure 3.42 Ready Queue Management by rot_rdq System Call..................................................- 51 -

Figure 3.43 Interrupt process flow..................................................................................................- 52 -

Figure 4.1 MR308 System Generation Detail Flowchart ..............................................................- 61 -

Figure 4.2 Program Example ..........................................................................................................- 63 -

Figure 4.3 Configuration File Example ..........................................................................................- 64 -

Figure 4.4 Configurator Execution .................................................................................................- 65 -

Figure 4.5 System Generation.........................................................................................................- 65 -

Figure 5.1 Example Infinite Loop Task Described in C Language...............................................- 68 -

Figure 5.2 Example Task Terminating with ext_tsk() Described in C Language........................- 68 -

Figure 5.3 Example of Kernel(OS-dependent) Interrupt Handler................................................- 70 -

Figure 5.4 Example of Non-kernel(OS-independent) Interrupt Handler.....................................- 71 -

Figure 5.5 Example Cyclic Handler Written in C Language ........................................................- 72 -

Figure 5.6 Example Infinite Loop Task Described in Assembly Language..................................- 73 -

Figure 5.7 Example Task Terminating with ext_tsk Described in Assembly Language.............- 73 -

Figure 5.8 Example of kernel(OS-depend) interrupt handler.......................................................- 75 -

Figure 5.9 Example of Non-kernel(OS-independent) Interrupt Handler of Specific Level.........- 76 -

Figure 5.10 Example Handler Written in Assembly Language ....................................................- 77 -

Figure 5.11 Interrupt handler IPLs................................................................................................- 79 -

Figure 5.12 Interrupt control in a System Call that can be Issued from only a Task.................- 80 -

Figure 5.13 Interrupt control in a System Call that can be Issued from a Task-independent ...- 81 -

Figure 5.14 C Language Startup Program (crt0mr.a30) ...............................................................- 88 -

Figure 5.15 Selection Allocation in C Language Startup Program...............................................- 93 -

Figure 6.1 The operation of the Configurator ..............................................................................- 124 -

Figure 7.1 Processing Procedure for a System Call a Handler that caused an interrupt during Task

Execution - 137 -

Figure 7.2 Processing Procedure for a System Call from a Handler that caused an interrupt during System

Call Processing........................................................................................................................- 138 -

Figure 7.3 Processing Procedure for a service call from a Multiplex interrupt Handler..........- 139 -

Figure 7.4 System Stack and User Stack .....................................................................................- 140 -

Figure 9.1 ROM separate ..............................................................................................................- 147 -

Figure 9.2 Memory map.................................................................................................................- 148 -

List of Tables

Table 3-1 Task Context and Non-task Context.....................................................................- 27 -

Table 3-2 Invocable Service Calls in a CPU Locked State ...................................................- 29 -

Table 3-3 CPU Locked and Dispatch Disabled State Transitions Relating to dis_dsp and loc_cpu - 29 -

Table 3.4 List of the service call can be issued from the task and handler.......................- 55 -

Table 5.1 C Language Variable Treatment..........................................................................- 69 -

Table 5.2 Interrupt Number Assignment............................................................................- 78 -

Table 6.1 Numerical Value Entry Examples.......................................................................- 96 -

Table 6.2 Operators...............................................................................................................- 97 -

Table 6.3 Interrupt Causes and Vector Numbers ...............................................................- 118 -

Table 8.1 Functions in the Sample Program.....................................................................- 142 -

Chapter 1 User’s Manual Organization

The MR308 User’s Manual consists of nine chapters and thee appendix.

• Chapter 2 General Information

Outlines the objective of MR308 development and the function and position of the MR308.

• Chapter 3 Introduction to MR308

Explains about the ideas involved in MR308 operations and defines some relevant terms.

• Chapter 4 Applications Development Procedure Overview

Outlines the applications program development procedure for the MR308.

• Chapter 5 Detailed Applications

Details the applications program development procedure for the MR308.

• Chapter 6 Using Configurator

Describes the method for writing a configuration file and the method for using the configurator in detail.

• Chapter 7 Application Creation Guide

Presents useful information and precautions concerning applications program development with MR308.

• Chapter 8 Sample Program Description

Describes the MR308 sample applications program which is included in the product in the form of a source file.

• Chapter 9 Separate ROMs

Explains about how to Form Separate ROMs.

- 2 -

Chapter 2 General Information

2.1 Objective of MR308 Development

In line with recent rapid technological advances in microcomputers, the functions of microcomputer-based products have become complicated. In addition, the microcomputer program size has increased. Further, as product development competition has been intensified, manufacturers are compelled to develop their microcomputer-based products within a short period of time.

In other words, engineers engaged in microcomputer software development are now required to develop larger-size programs within a shorter period of time. To meet such stringent requirements, it is necessary to take the following considerations into account.

1. To enhance software recyclability to decrease the volume of software to be developed.

One way to provide for software recyclability is to divide software into a number of functional modules wherever possible. This may be accomplished by accumulating a number of general-purpose subroutines and other program segments and using them for program development. In this method, however, it is difficult to reuse programs that are dependent on time or timing. In reality, the greater part of application programs are dependent on time or timing. Therefore, the above recycling method is applicable to only a limited number of programs.

2. To promote team programming so that a number of engineers are engaged in the development of one software package

There are various problems with team programming. One major problem is that debugging can be initiated only when all the software program segments created individually by team members are ready for debugging. It is essential that communication be properly maintained among the team members.

3. To enhance software production efficiency so as to increase the volume of possible software development per engineer.

One way to achieve this target would be to educate engineers to raise their level of skill. Another way would be to make use of a structured descriptive assembler, C-compiler, or the like with a view toward facilitating programming. It is also possible to enhance debugging efficiency by promoting modular software development.

However, the conventional methods are not adequate for the purpose of solving the problems. Under these circumstances, it is necessary to introduce a new system named real-time OS

To answer the above-mentioned demand, Renesas has developed a real-time operating system, tradenamed MR308, for use with the M16C/70, 80 and M32C/80 series of 16/32-bit microcomputers .

When the MR308 is introduced, the following advantages are offered.

4. Software recycling is facilitated.

When the real-time OS is introduced, timing signals are furnished via the real-time OS so that programs dependent on timing can be reused. Further, as programs are divided into modules called tasks, structured programming will be spontaneously provided.

That is, recyclable programs are automatically prepared.

5. Ease of team programming is provided.

When the real-time OS is put to use, programs are divided into functional modules called tasks. Therefore, engineers can be allocated to individual tasks so that all steps from development to debugging can be conducted independently for each task.

Further, the introduction of the real-time OS makes it easy to start debugging some already finished tasks even if the entire program is not completed yet. Since engineers can be allocated to individual tasks, work assignment is easy.

6. Software independence is enhanced to provide ease of program debugging.

As the use of the real-time OS makes it possible to divide programs into small independent modules called tasks, the greater part of program debugging can be initiated simply by observing the small modules.

OS:Operating System

- 4 -

Chapter 2 General Information

7. Timer control is made easier.

To perform processing at 10 ms intervals, the microcomputer timer function was formerly used to periodically initiate an interrupt. However, as the number of usable microcomputer timers was limited, timer insufficiency was compensated for by, for instance, using one timer for a number of different processing operations.

When the real-time OS is introduced, however, it is possible to create programs for performing processing at fixed time intervals making use of the real-time OS time management function without paying special attention to the microcomputer timer function. At the same time, programming can also be done in such a manner as to let the programmer take that numerous timers are provided for the microcomputer.

8. Software maintainability is enhanced

When the real-time OS is put to use, the developed software consists of small program modules called tasks. Therefore, increased software maintainability is provided because developed software maintenance can be carried out simply by maintaining small tasks.

9. Increased software reliability is assured.

The introduction of the real-time OS makes it possible to carry out program evaluation and testing in the unit of a small module called task. This feature facilitates evaluation and testing and increases software reliability.

10. The microcomputer performance can be optimized to improve the performance of microcomputer-based products.

With the real-time OS, it is possible to decrease the number of unnecessary microcomputer operations such as I/O waiting. It means that the optimum capabilities can be obtained from microcomputers, and this will lead to microcomputer-based product performance improvement.

- 5 -

Chapter 2 General Information

2.2 Relationship between TRON Specification and MR308

The TRON Specification is an abbreviation for The Real-time Operating system Nucleus specification. It denotes the specifications for the nucleus of a real-time operating system. The TRON Project, which is centered on TRON Specification design, is pushed forward under the leadership of Dr. Ken Sakamura at University of Tokyo.

As one item of this TRON Project, the ITRON Specification is promoted. The ITRON Specification is an abbreviation for the Industrial TRON Specification. It denotes the real-time operating system that is designed with a view toward establishing industrial real-time operating systems.

The ITRON Specification provides a number of functions to properly meet the application requirements. In other words, ITRON systems require relatively large memory capacities and enhanced processing capabilities. The µITRON 2.0 Specification is the arranged version of the ITRON Specification for the higher processing speed, and incorporated only a minimum of functions necessary.

In 1993, µITRON 2.0 Specification and ITRON Specification were unified, which resulted in establishment of µITRON 3.0 Specification, with connecting functions added.

Furthermore, in 1999, µITRON 4.0 Specification

MR308 is the real-time operating system developed for use with the M16C/70, 80 and M32C/80 series of 16/32-bit microcomputers compliant with µITRON 4.0 Specification. µITRON 4.0 Specification stipulates standard profiles as an attempt to ensure software portability. Of these standard profiles, MR308 has implemented in it all service calls except for static APIs and task exception APIs.

with enhanced compatibility was established.

µITRON 4.0 Specification is an open, real-time kernel specification set forth by the TRON Association. The documented specification of µITRON 4.0 Specification can be obtained from the Web site of the TRON Association (http://www.assoc.tron.org/).

- 6 -

Chapter 2 General Information

2.3 MR308 Features

The MR308 offers the following features.

1. Real-time operating system conforming to the µITORN Specification.

The MR308 is designed in compliance with the µITRON Specification which incorporates a minimum of the ITRON Specification functions so that such functions can be incorporated into a one-chip microcomputer. As the µITRON Specification is a subset of the ITRON Specification, most of the knowledge obtained from published ITRON textbooks and ITRON seminars can be used as is.

Further, the application programs developed using the real-time operating systems conforming to the ITRON Specification can be transferred to the MR308 with comparative ease.

2. High-speed processing is achieved.

MR308 enables high-speed processing by taking full advantage of the microcomputer architecture.

3. Only necessary modules are automatically selected to constantly build up a system of the minimum size.

MR308 is supplied in the object library format of the M16C/70, 80 and M32C/80 series.

Therefore, the Linkage Editor LN308 functions are activated so that only necessary modules are automatically selected from numerous MR308 functional modules to generate a system.

Thanks to this feature, a system of the minimum size is automatically generated at all times.

4. With the C-compiler NC308WA, it is possible to develop application programs in C language.

Application programs of MR308 can be developed in C language by using the C compiler NC308WA. Furthermore, the interface library necessary to call the MR308 functions from C language is included with the software package.

5. An upstream process tool named "Configurator" is provided to simplify development procedures

A configurator is furnished so that various items including a ROM write form file can be created by giving simple definitions.

Therefore, there is no particular need to care what libraries must be linked.

In addition, a GUI version of the configurator is available beginning with M3T-MR308 V.4.00. It helps the user to create a configuration file without the need to learn how to write it.

- 7 -

Chapter 3 Introduction to MR308

3.1 Concept of Real-time OS

This section explains the basic concept of real-time OS.

3.1.1 Why Real-time OS is Necessary

In line with the recent advances in semiconductor technologies, the single-chip microcomputer ROM capacity has increased. ROM capacity of 32K bytes.

As such large ROM capacity microcomputers are introduced, their program development is not easily carried out by conventional methods. Fig.3.1 shows the relationship between the program size and required development time (program development difficulty).

This figure is nothing more than a schematic diagram. However, it indicates that the development period increases exponentially with an increase in program size.

For example, the development of four 8K byte programs is easier than the development of one 32K byte pro-

gram.

Development Period

Program Size

Kbyte

Figure 3.1 Relationship between Program Size and Development Period

Under these circumstances, it is necessary to adopt a method by which large-size programs can be developed within a short period of time. One way to achieve this purpose is to use a large number of microcomputers having a small ROM capacity. Figure 3.2 presents an example in which a number of microcomputers are used to build up an audio equipment system.

On condition that the ROM program burning step need not be performed.

- 10 -

Chapter 3 Introduction to MR308

Key input

microcomputer

Volume control microcomputer

Remote control microcomputer

Arbiter

microcomputer

Monitor

microcomputer

LED illumination

microcomputer

Mechanical

control

microcom

uter

Figure 3.2 Microcomputer-based System Example(Audio Equipment)

Using independent microcomputers for various functions as indicated in the above example offers the following advantages.

1. Individual programs are small so that program development is easy.

2. It is very easy to use previously developed software.

3. Completely independent programs are provided for various functions so that program development can easily be conducted by a number of engineers.

On the other hand, there are the following disadvantages.

1. The number of parts used increases, thereby raising the product cost.

2. Hardware design is complicated.

3. Product physical size is enlarged.

Therefore, if you employ the real-time OS in which a number of programs to be operated by a number of microcomputers are placed under software control of one microcomputer, making it appear that the programs run on separate microcomputers, you can obviate all the above disadvantages while retaining the above-mentioned advantages.

Figure 3.3 shows an example system that will be obtained if the real-time OS is incorporated in the system indicated in Figure 3.2.

In the case presented in エラー! 参照元が見つかりません。 for instance, the remote control microcomputer can be used for other prod-

ucts without being modified.

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Chapter 3 Introduction to MR308

Key input

Tas k

Remote control

Task

LED illumination

Task

real-time

Volume control

Task

Monitor

Tas k

Mechanical

control

Task

Figure 3.3 Example System Configuration with Real-time OS(Audio Equipment)

In other words, the real-time OS is the software that makes a one-microcomputer system look like operating a number of microcomputers.

In the real-time OS, the individual programs, which correspond to a number of microcomputers used in a conventional system, are called tasks.

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Chapter 3 Introduction to MR308

3.1.2 Operating Principles of Real-time OS

The real-time OS is the software that makes a one-microcomputer system look like operating a number of microcomputers. You should be wondering how the real-time OS makes a one-microcomputer system function like a number of microcomputers.

As shown in Figure 3.4 the real-time OS runs a number of tasks according to the time-division system. That is, it changes the task to execute at fixed time intervals so that a number of tasks appear to be executed simultaneously.

Key input

Task

Remote control

Task

LED

illumination

Task

Volume control

Task

Monitor

Task

Mechanical

control

Task

Time

Figure 3.4 Time-division Task Operation

As indicated above, the real-time OS changes the task to execute at fixed time intervals. This task switching may also be referred to as dispatching (technical term specific to real-time operating systems). The factors causing task switching (dispatching) are as follows.

• Task switching occurs upon request from a task.

• Task switching occurs due to an external factor such as interrupt.

When a certain task is to be executed again upon task switching, the system resumes its execution at the point of last interruption (See Figure 3.5).

Program execution

interrupt

Program execution

resumed

Key input

Task

Remote control

Task

During this interval, it appears that the key input microcomputer is haled.

Figure 3.5 Task Execution Interruption and Resumption

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Chapter 3 Introduction to MR308

In the state shown in Figure 3.5, it appears to the programmer that the key input task or its microcomputer is halted while another task assumes execution control.

Task execution restarts at the point of last interruption as the register contents prevailing at the time of the last interruption are recovered. In other words, task switching refers to the action performed to save the currently executed task register contents into the associated task management memory area and recover the register contents for the task to switch to.

To establish the real-time OS, therefore, it is only necessary to manage the register for each task and change the register contents upon each task switching so that it looks as if a number of microcomputers exist (See Figure 3.6).

Real-time OS

ctual

Key input

Tas k

Remote control

Tas k

RegisterRegister

Figure 3.6 Task Switching

The example presented in Figure 3.7

indicates how the individual task registers are managed. In reality, it is

necessary to provide not only a register but also a stack area for each task.

It is figure where all the stack areas of the task were arranged in the same section.

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Remote control

Task

Key input

Tas k

LED illumination

Task

Chapter 3 Introduction to MR308

Memory map

Stack section

Real-time

SFR

Figure 3.7 Task Register Area

Figure 3.8 shows the register and stack area of one task in detail. In the MR308, the register of each task is stored in a stack area as shown in Figure 3.8. This figure shows the state prevailing after register storage.

Key input

Task

FLG

Key input task stack

SFR

Figure 3.8 Actual Register and Stack Area Management

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Chapter 3 Introduction to MR308

3.2 Service Call

How does the programmer use the real-time OS in a program?

First, it is necessary to call up a real-time OS function from the program in some way or other. Calling a real-time OS function is referred to as a service call. Task activation and other processing operations can be initiated by such a service call (See Figure 3.9).

Key input

Task

Service call Task switching

Real-time OS

Figure 3.9 Service call

This service call is realized by a function call when the application program is written in C language, as shown below.

sta_tsk(ID_main,3);

Remote control

task

Furthermore, if the application program is written in assembly language, it is realized by an assembler macro call, as shown below.

sta_tsk #ID_main,#3

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Chapter 3 Introduction to MR308

3.2.1 Service Call Processing

When a service call is issued, processing takes place in the following sequence.8

1. The current register contents are saved.

2. The stack pointer is changed from the task type to the real-time OS (system) type.

3. Processing is performed in compliance with the request made by the service call.

4. The task to be executed next is selected.

5. The stack pointer is changed to the task type.

6. The register contents are recovered to resume task execution.

The flowchart in Figure 3.10 shows the process between service call generation and task switching.

Key input Task

Service call issuance

Figure 3.10 Service Call Processing Flowchart

<= OS

Processing

Task S elect ion

Task => S P

LED illumination Task

A different sequence is followed if the issued service call does not evoke task switching.

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Chapter 3 Introduction to MR308

3.2.2 Task Designation in Service call

Each task is identified by the ID number internally in MR308.

For example, the system says, "Start the task having the task ID number 1."

However, if a task number is directly written in a program, the resultant program would be very low in readability. If, for instance, the following is entered in a program, the programmer is constantly required to know what the No. 2 task is.

sta_tsk(2,1);

Further, if this program is viewed by another person, he/she does not understand at a glance what the No. 2 task is. To avoid such inconvenience, the MR308 provides means of specifying the task by name (function or symbol name).

The program named "configurator cfg308 ,"which is supplied with the MR308, then automatically converts the task name to the task ID number. This task identification system is schematized in Figure 3.11.

sta_tsk(Task name)

Name

Configurator

ID number

Starting the task having the designated ID number

Real-time OSProgram

Figure 3.11 Task Identification

sta_tsk(ID_task,1);

This example specifies that a task corresponding to "ID_task" be invoked.

It should also be noted that task name-to-ID number conversion is effected at the time of program generation. Therefore, the processing speed does not decrease due to this conversion feature.

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Chapter 3 Introduction to MR308

3.3 Task

This section describes how tasks are managed by MR308.

3.3.1 Task Status

The real-time OS monitors the task status to determine whether or not to execute the tasks.

Figure 3.12 shows the relationship between key input task execution control and task status. When there is a key input, the key input task must be executed. That is, the key input task is placed in the execution (RUNNING) state. While the system waits for key input, task execution is not needed. In that situation, the key input task in the WAITING state.

Key input

Task

Key input processing

RUNNIG state WAITING state RUNNING state

Figure 3.12 Task Status

Waiting for key input

Key input

rocessing

The MR308 controls the following six different states including the RUNNING and WAITING states.

1. RUNNING state

2. READY state

3. WAITING state

4. SUSPENDED state

5. WAITING-SUSPENDED state

6. DORMANT state

Every task is in one of the above six different states. Figure 3.13 shows task status transition.

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READY state

Chapter 3 Introduction to MR308

MPU execlusive right acquisition

MPU execlusive right relinquishment

WAITING state

RUNNING state

Entering the WAITING state

SUSPENDED state clear request from other task

SUSPEND request from other task

Forced termin ation request from other task

WAITING-SUSPENDED

state

WAITING state

SUSPEND request

clear

from other task

SUSPENDED

SUSPENDED state

state

clear request

Forced termination request from other task

DORMANT

state

Task activation

Figure 3.13 MR308 Task Status Transition

1. RUNNING state

In this state, the task is being executed. Since only one microcomputer is used, it is natural that only one task is being executed.

The currently executed task changes into a different state when any of the following conditions occurs.

♦ The task has normally terminated itself. ♦ The task has placed itself in the WAITING state.

♦ Due to interruption or other event occurrence, the interrupt handler has placed a different task

having a higher priority in the READY state.

♦ The priority assigned to the task has been changed so that the priority of another READY task is

rendered higher.

♦ Due to interruption or other event occurrence, the priority of the task or a different READY task

has been changed so that the priority of the different task is rendered higher.

♦ When the ready queue of the issuing task priority is rotated by the rot_rdq or irot_rdq service call

and control of execution is thereby abandoned

When any of the above conditions occurs, rescheduling takes place so that the task having the highest priority among those in the RUNNING or READY state is placed in the RUNNING state, and the execution of that task starts.

2. READY state

The READY state refers to the situation in which the task that meets the task execution conditions is still waiting for execution because a different task having a higher priority is currently being executed.

When any of the following conditions occurs, the READY task that can be executed second according

Depends on the ext_tsk service call.

Depends on the dly_tsk, slp_tsk, tslp_tsk, wai_flg, twai_flg, wai_sem, twai_sem, rcv_mbx, trcv_mbx,snd_dtq,tsnd_dtq,rcv_dtq, trcv_dtq,

vtsnd_dtq, vsnd_dtq,vtrcv_dtq,tget_mpf, get_mpf or vrcv_dtq service call.

Depends on the chg_pri service call.

Depends on the ichg_pri service call.

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to the ready queue

♦ A currently executed task has normally terminated itself. ♦ A currently executed task has placed itself in the WAITING state. ♦ A currently executed task has changed its own priority so that the priority of a different READY

task is rendered higher.

♦ Due to interruption or other event occurrence, the priority of a currently executed task has been

changed so that the priority of a different READY task is rendered higher.

♦ When the ready queue of the issuing task priority is rotated by the rot_rdq or irot_rdq service call

and control of execution is thereby abandoned

3. WAITING state

When a task in the RUNNING state requests to be placed in the WAITING state, it exits the RUNNING state and enters the WAITING state. The WAITING state is usually used as the condition in which the completion of I/O device I/O operation or the processing of some other task is awaited.

The task goes into the WAITING state in one of the following ways.

♦ The task enters the WAITING state simply when the slp_tsk service call is issued. In this case, the

task does not go into the READY state until its WAITING state is cleared explicitly by some other task.

♦ The task enters and remains in the WAITING state for a specified time period when the dly_tsk

service call is issued. In this case, the task goes into the READY state when the specified time has elapsed or its WAITING state is cleared explicitly by some other task.

♦ The task is placed into WAITING state for a wait request by the wai_flg, wai_sem, rcv_mbx,

snd_dtq, rcv_dtq, vsnd_dtq, vrcv_dtq, or get_mpf service call. In this case, the task goes from WAITING state to READY state when the request is met or WAITING state is explicitly canceled by another task.

♦ The tslp_tsk, twai_flg, twai_sem, trcv_mbx, tsnd_dtq, trcv_dtq, vtsnd_dtq, vtrcv_dtq, and tget_mpf

service calls are the timeout-specified versions of the slp_tsk, wai_flg, wai_sem, rcv_mbx, snd_dtq, rcv_dtq, vsnd_dtq, vrcv_dtq, and get_mpf service calls. The task is placed into WAITING state for a wait request by one of these service calls. In this case, the task goes from WAITING state to READY state when the request is met or the specified time has elapsed.

♦ If the task is placed into WAITING state for a wait request by the wai_flg, wai_sem, rcv_mbx,

snd_dtq, rcv_dtq, vsnd_dtq, vrcv_dtq, get_mpf, twai_flg, twai_sem, trcv_mbx, tsnd_dtq, trcv_dtq, vtsnd_dtq, vtrcv_dtq, or tget_mpf service call queues depending on the request.

Chapter 3 Introduction to MR308

is placed in the RUNNING state.

, the task is queued to one of the following waiting

• Event flag waiting queue

• Semaphore waiting queue

• Mailbox message reception waiting queue

• Data queue data transmission waiting queue

• Data queue data reception waiting queue

• Short data queue data transmission waiting queue

• Short data queue data reception waiting queue

• Fixed-size memory pool acquisition waiting queue

For the information on the ready queue,see the next chapter.

Depends on the ext_tsk service call.

Depends on the dly_tsk, slp_tsk, tslp_tsk, wai_flg, twai_flg, wai_sem, twai_sem, rcv_mbx, trcv_mbx,snd_dtq,tsnd_dtq,rcv_dtq, trcv_dtq,

vtsnd_dtq, vsnd_dtq,vtrcv_dtq,tget_mpf, get_mpf or vrcv_dtq service call.

Depends on the chg_pri service call.

Depends on the ichg_pri service call.

The service call twai_flg, twai_sem, and trcv_msg are included.

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4. SUSPENDED state

When the sus_tsk system call is issued from a task in the RUNNING state or the isus_tsk system call is issued from a handler, the READY task designated by the system call or the currently executed task enters the SUSPENDED state. If a task in the WAITING state is placed in this situation, it goes into the WAITING-SUSPENDED state.

The SUSPENDED state is the condition in which a READY task or currently executed task cluded from scheduling to halt processing due to I/O or other error occurrence. That is, when the suspend request is made to a READY task, that task is excluded from the execution queue.

Chapter 3 Introduction to MR308

is ex-

Note that no queue is formed for the suspend request. Therefore, the suspend request can only be made to the tasks in the RUNNING, READY, or WAITING state.

If the suspend request is made to a

task in the SUSPENDED state, an error code is returned.

5. WAITING-SUSPENDED

If a forcible wait request is issued to a task currently in a wait state, the task goes to a WAITING-SUSPENDED state. If a forcible wait request is issued to a task that has been placed into a wait state for a wait request by the slp_tsk, wai_flg, wai_sem, rcv_mbx, snd_dtq, rcv_dtq, vsnd_dtq, vrcv_dtq, get_mpf, tslp_tsk, twai_flg, twai_sem, trcv_mbx, tsnd_dtq, trcv_dtq, vtsnd_dtq, vtrcv_dtq, or tget_mpf service call, the task goes to a dual-wait state.

When the wait condition for a task in the WAITING-SUSPENDED state is cleared, that task goes into the SUSPENDED state. It is conceivable that the wait condition may be cleared, when any of the following conditions occurs.

♦ The task wakes up upon wup_tsk, or iwup_tsk service call issuance. ♦ The task placed in the WAITING state by the dly_tsk or tslp_tsk service call wakes up after the

specified time elapse.

♦ The request of the task placed in the WAITING state by the wai_flg , wai_sem, rcv_mbx, snd_dtq,

rcv_dtq, vsnd_dtq, vrcv_dtq, get_mpf, tslp_tsk, twai_flg, twai_sem, trcv_mbx, tsnd_dtq, trcv_dtq, vtsnd_dtq, vtrcv_dtq, or tget_mpf service call is fulfilled.

♦ The WAITING state is forcibly cleared by the rel_wai or irel_wai service call

When the SUSPENDED state clear request

is made to a task in the WAITING-SUSPENDED state, that task goes into the WAITING state. Since a task in the SUSPENDED state cannot request to be placed in the WAITING state, status change from SUSPENDED to WAITING-SUSPENDED does not possibly occur.

6. DORMANT

This state refers to the condition in which a task is registered in the MR308 system but not activated. This task state prevails when either of the following two conditions occurs.

♦ The task is waiting to be activated. ♦ The task is normally terminated

If the task under execution is placed into a forcible wait state by the isus_tsk service call from the handler, the task goes from an executing state directly to a forcible wait state. Please note that in only this case exceptionally, it is possible that a task will go from an executing state directly to a forcible wait state.

If a forcible wait request is issued to a task currently in a wait state, the task goes to a dual-wait state.

rsm_tsk or irsm_tsk service calls

ext_tsk service call

ter_tsk service call

or forcibly terminated.23

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Chapter 3 Introduction to MR308

3.3.2 Task Priority and Ready Queue

In the real-time OS, several tasks may simultaneously request to be executed. In such a case, it is necessary to determine which task the system should execute first. To properly handle this kind of situation, the system organizes the tasks into proper execution priority and starts execution with a task having the highest priority. To complete task execution quickly, tasks related to processing operations that need to be performed immediately should be given higher priorities.

The MR308 permits giving the same priority to several tasks. To provide proper control over the READY task execution order, the system generates a task execution queue called "ready queue." The ready queue structure is shown in Figure 3.14 ready queue having the highest priority is placed in the RUNNING state.

The ready queue is provided and controlled for each priority level. The first task in the

Priority

TCB

TCBTCB

Figure 3.14 Ready Queue (Execution Queue)

TCB

The TCB(task control block is described in the next chapter.)

The task in the RUNNING state remains in the ready queue.

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Chapter 3 Introduction to MR308

3.3.3 Task Priority and Waiting Queue

In The standard profiles in µITRON 4.0 Specification support two waiting methods for each object. In one method, tasks are placed in a waiting queue in order of priority (TA_TPRI attribute); in another, tasks are placed in a waiting queue in order of FIFO (TA_TFIFO). Figure 3.15 and Figure 3.16 depict the manner in which tasks are placed in a waiting queue in order of "taskD," "taskC," "taskA," and "taskB."

ID No.

taskA taskC taskD

Priority 1 Priority 5 Priority 6

taskB

Figure 3.15 Waiting queue of the TA_TPRI attribute

taskD taskA taskB

Priority 9 Priority 6 Priority 1

taskC

Priority 9

Priority 5

Figure 3.16 Waiting queue of the TA_TFIFO attribute

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Chapter 3 Introduction to MR308

3.3.4 Task Control Block(TCB)

The task control block (TCB) refers to the data block that the real-time OS uses for individual task status, priority, and other control purposes.

The MR308 manages the following task information as the task control block

• Task connection pointer

Task connection pointer used for ready queue formation or other purposes.

• Task status

• Task priority

• Task register information and other data

storage stack area pointer(current SP register value)

• Wake-up counter

Task wake-up request storage area.

• Time-out counter or wait flag pattern

When a task is in a time-out wait state, the remaining wait time is stored; if in a flag wait state, the flag's wait pattern is stored in this area.

• Flag wait mode

This is a wait mode during eventflag wait.

• Timer queue connection pointer

This area is used when using the timeout function. This area stores the task connection pointer used when constructing the timer queue.

• Flag wait pattern

This area is used when using the timeout function.

This area stores the flag wait pattern when using the eventflag wait service call with the timeout function (twai_flg). No flag wait pattern area is allocated when the eventflag is not used.

• Startup request counter

This is the area in which task startup requests are accumulated.

• Extended task information

Extended task information that was set during task generation is stored in this area.

The task control block is schematized in Figure 3.17.

Called the task context

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Chapter 3 Introduction to MR308

TCB

Task Connection pointer

Status

Priority

Wake-up counter

Flag wait mode

Time-out counter

Flag wait pattern

Timer queue

Connection pointer

Flag wait pattern

TCBTCB

This area is allocated only when the timeout function is used.

Figure 3.17 Task control block

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Chapter 3 Introduction to MR308

3.4 System States

3.4.1 Task Context and Non-task Context

The system runs in either context state, "task context" or "non-task context." The differences between the task content and non-task context are shown in Table 3-1. Task Context and Non-task Context.

Table 3-1 Task Context and Non-task Context

Task context Non-task context

Invocable service call Those that can be invoked from

task context

Task scheduling Occurs when the queue state

has changed to other than dispatch disabled and CPU locked states.

Stack User stack System stack

The processes executed in non-task context include the following.

Those that can be invoked from non-task context

It does not occur.

1. Interrupt Handler

A program that starts upon hardware interruption is called the interrupt handler. The MR308 is not concerned in interrupt handler activation. Therefore, the interrupt handler entry address is to be directly written into the interrupt vector table.

There are two interrupt handlers: Non-kernel interrupts (OS independent interrupts) and kernel interrupts (OS dependent interrupts). For details about each type of interrupt, refer to Section 5.5.

The system clock interrupt handler (isig_tim) is one of these interrupt handlers.

2. Cyclic Handler

The cyclic handler is a program that is started cyclically every preset time. The set cyclic handler may be started or stopped by the sta_cyc(ista_cyc) or stp_cyc(istp_cyc) service call.

The cyclic handler startup time of day is unaffected by a change in the time of day by set_tim(iset_tim).

3. Alarm Handler

The alarm handler is a handler that is started after the lapse of a specified relative time of day. The alarm handler startup time of day is determined by a time of day relative to the time of day set by sta_alm(ista_alm), and is unaffected by a change in the time of day by set_tim(iset_tim).

The cyclic and alarm handlers are invoked by a subroutine call from the system clock interrupt (timer interrupt) handler. Therefore, cyclic and alarm handlers operate as part of the system clock interrupt handler. Note that when the cyclic or alarm handler is invoked, it is executed in the interrupt priority level of the system clock interrupt.

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Chapter 3 Introduction to MR308

Task

System clock interrupt handler

Cyclic handler

larm handler

Subroutine call

Timer interrupt

RTS

Figure 3.18 Cyclic Handler/Alarm Handler Activation

3.4.2 Dispatch Enabled/Disabled States

The system assumes either a dispatch enabled state or a dispatch disabled state. In a dispatch disabled state, no task scheduling is performed. Nor can service calls be invoked that may cause the service call issuing task to enter a wait state. The system can be placed into a dispatch disabled state or a dispatch enabled state by the dis_dsp or ena_dsp service call, respectively. Whether the system is in a dispatch disabled state can be known by the sns_dsp service call.

If a service call not issuable is issued when dispatch disabled, MR308 doesn't return the error and doesn't guarantee the operation.

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Chapter 3 Introduction to MR308

3.4.3 CPU Locked/Unlocked States

The system assumes either a CPU locked state or a CPU unlocked state. In a CPU locked state, all external

interrupts are disabled against acceptance, and task scheduling is not performed either.

The system can be placed into a CPU locked state or a CPU unlocked state by the loc_cpu(iloc_cpu) or unl_cpu(iunl_cpu) service call, respectively. Whether the system is in a CPU locked state can be known by the sns_loc service call.

The service calls that can be issued from a CPU locked state are limited to those that are listed in Table 3-2.

Table 3-2 Invocable Service Calls in a CPU Locked State

loc_cpu iloc_cpu unl_cpu iunl_cpu ext_tsk exd_tsk sns_tex sns_ctx sns_loc sns_dsp sns_dpn

3.4.4 Dispatch Disabled and CPU Locked States

In µITRON 4.0 Specification, the dispatch disabled and the CPU locked states are clearly discriminated. Therefore, if the unl_cpu service call is issued in a dispatch disabled state, the dispatch disabled state remains intact and no task scheduling is performed. State transitions are summarized in Table 3-3.

Table 3-3 CPU Locked and Dispatch Disabled State Transitions Relating to dis_dsp and loc_cpu

State

number

CPU locked

state

Content of state

Dispatch disabled

state

dis_dsp executed

ena_dsp executed

loc_cpu executed

unl_cpu executed

1 O X X X => 1 => 3 2 O O X X => 2 => 4 3 X X => 4 => 3 => 1 => 3 4 X O => 4 => 3 => 2 => 4

MR308 does not return an error even when an uninvocable service call is issued from a CPU locked state, in which case, however, its

operation cannot be guaranteed.

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Chapter 3 Introduction to MR308

3.5 MR308 Kernel Structure

3.5.1 Module Structure

The MR308 kernel consists of the modules shown in Figure 3.19. Each of these modules is composed of functions that exercise individual module features.

The MR308 kernel is supplied in the form of a library, and only necessary features are linked at the time of system generation. More specifically, only the functions used are chosen from those which comprise these modules and linked by means of the Linkage Editor LN308. However, the scheduler module, part of the task management module, and part of the time management module are linked at all times because they are essential feature functions.

The applications program is a program created by the user. It consists of tasks, interrupt handler, alarm handler, and cyclic handler.

User Module

Application Program

Task

Management

Task-dependent synchronization

System configuration

Management

Mailbox

Eventflag

Scheduler

Semaphore

Memorypool

Management

Data queue

Time

Management

System stae

Management

Interrupt

Management

MR308 kernel

Hardware

M32C Microcomputer

Figure 3.19 MR308 Structure

For details, See 3.5.10.

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Chapter 3 Introduction to MR308

3.5.2 Module Overview

The MR308 kernel modules are outlined below.

• Scheduler

Forms a task processing queue based on task priority and controls operation so that the high-priority task at the beginning in that queue (task with small priority value) is executed.

• Task Management Module

Exercises the management of various task states such as the RUNNING, READY, WAIT, and SUSPENDED state.

• Task Synchronization Module

Accomplishes inter-task synchronization by changing the task status from a different task.

• Interrupt Management Module

Makes a return from the interrupt handler.

• Time Management Module

Sets up the system timer used by the MR308 kernel and starts the user-created alarm handler30 and cyclic handler.31.

• System Status Management Module

Gets the system status of MR308.

• System Configuration Management Module

Reports the MR308 kernel version number or other information.

• Sync/Communication Module

This is the function for synchronization and communication among the tasks. The following three functional modules are offered.

♦ Eventflag

Checks whether the flag controlled within the MR308 is set up and then determines whether or not to initiate task execution. This results in accomplishing synchronization between tasks.

♦ Semaphore

Reads the semaphore counter value controlled within the MR308 and then determines whether or not to initiate task execution. This also results in accomplishing synchronization between tasks.

♦ Mailbox

Provides inter-task data communication by delivering the first data address.

♦ Data queue

Performs 32-bit data communication between tasks.

• Memory pool Management Module

Provides dynamic allocation or release of a memory area used by a task or a handler.

• Extended Function Module

Outside the scope of µITRON 4.0 Specification , this function performs reset processing on short data queues and objects.

This handler actuates once only at preselected times.

This handler periodically actuates.

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Chapter 3 Introduction to MR308

3.5.3 Task Management Function

The task management function is used to perform task operations such as task start/stop and task priority updating. The MR308 kernel offers the following task management function service calls.

• Activate Task (act_tsk, iact_tsk)

Activates the task, changing its status from DORMANT to either READY or RUNNING. In this service call, unlike in sta_tsk(ista_tsk), startup requests are accumulated, but startup code cannot be specified.

• Activate Task (sta_tsk, ista_tsk)

Activates the task, changing its status from DORMANT to either READY or RUNNING. In this service call, unlike in act_tsk(iact_tsk), startup requests are not accumulated, but startup code can be specified.

• Terminate Invoking Task (ext_tsk)

When the issuing task is terminated, its state changes to DORMANT state. The task is therefore not executed until it is restarted. If startup requests are accumulated, task startup processing is performed again. In that case, the issuing task behaves as if it were reset.

If written in C language, this service call is automatically invoked at return from the task regardless of whether it is explicitly written when terminated.

• Terminate Task (ter_tsk)

Other tasks in other than DORMANT state are forcibly terminated and placed into DORMANT state. If startup requests are accumulated, task startup processing is performed again. In that case, the issuing task behaves as if it were reset. (See Figure 3.20).

TaskA

Startup request count > 0

TaskB

ter_tsk(B)

Ter mi nat ed

Task B reset

Figure 3.20 Task Resetting

• Change Task Priority (chg_pri, ichg_pri)

If the priority of a task is changed while the task is in READY or RUNNING state, the ready queue also is updated. (See Figure 3.21).

Furthermore, if the target task is placed in a waiting queue of objects with TA_TPRI attribute, the waiting queue also is updated. (See Figure 3.22).

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Priority

ID Number

１

Task A

Task C

When the priority of task B has been changed from 3 to 1

Task B

Task FTas k E

Figure 3.21 Alteration of task priority

Task D

２

３

ｎ

taskA

Priority 1 Priority 2 Priority 3 Priority 4

When the priority of Task B is changed into 4

taskB

Figure 3.22 Task rearrangement in a waiting queue

• Reference task priority (get_pri, iget_pri)

Gets the priority of a task.

• Reference task status (simple version) (ref_tst, iref_tst)

Refers to the state of the target task.

• Reference task status (ref_tsk, iref_tsk)

Refers to the state of the target task and its priority, etc.

taskC taskB

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3.5.4 Synchronization functions attached to task

The task-dependent synchronization functions attached to task is used to accomplish synchronization between tasks by placing a task in the WAIT, SUSPENDED, or WAIT-SUSPENDED state or waking up a WAIT state task.

The MR308 offers the following task incorporated synchronization service calls.

• Put Task to sleep (slp_tsk,tslp_tsk)

• Wakeup task (wup_tsk, iwup_tsk)

Wakeups a task that has been placed in a WAIT state by the slp_tsk or tslp_tsk service call.

No task can be waked up unless they have been placed in a WAIT state by.

If a wakeup request is issued to a task that has been kept waiting for conditions other than the slp_tsk or tslp_tsk service call or a task in other than DORMANT state by the wup_tsk or iwup_tsk service call, that wakeup request only will be accumulated.

Therefore, if a wakeup request is issued to a task RUNNING state, for example, this wakeup request is temporarily stored in memory. Then, when the task in RUNNING state is going to be placed into WAIT state by the slp_tsk or tslp_tsk service call, the accumulated wakeup request becomes effective, so that the task continues executing again without going to WAIT state. (See Figure 3.23).

• Cancel Task Wakeup Requests (can_wup)

Clears the stored wakeup request.(See Figure 3.24).

Task

Wakeup request count

Task

Wakeup r equest co un t

wup_tsk wup_tsk wup_tsk

slp_tsk slp_tsk

0 0 1 2 1

Figure 3.23 Wakeup Request Storage

wup_tsk wup_tsk can_wup

slp_tsk slp_tsk

0 0 1 0

Figure 3.24 Wakeup Request Cancellation

• Suspend task (sus_tsk, isus_tsk)

• Resume suspended task (rsm_tsk, irsm_tsk)

These service calls forcibly keep a task suspended for execution or resume execution of a task. If a suspend request is issued to a task in READY state, the task is placed into SUSPENDED state; if issued to a task in WAIT state, the task is placed into WAIT-SUSPENDED state. Since MR308 allows

Note that tasks in WAIT state, but kept waiting for the following conditions are not awaken.

Eventflag wait state, semaphore wait state, data transmission wait state, data reception wait state, timeout wait state, fixed length memory pool acquisition wait, short data transmission wait, or short data reception wait

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Chapter 3 Introduction to MR308

only one forcible wait request to be nested, if sus_tsk is issued to a task in a forcible wait state, the error E_QOVR is returned. (See Figure 3.25).

E_QOVR

rsm_tsk sus_tsk

READY state

Task

RUNNING

state

sus_tsk

SUSPENDED

state

WAITING-

SUSPENDED

WAITING stateWAI TIN G s ta te

state

Number of

suspension

request

0 1 1 0

Figure 3.25 Forcible wait of a task and resume

• Forcibly resume suspended task (frsm_tsk, ifrsm_tsk)

Clears the number of suspension requests nested to 0 and forcibly resumes execution of a task. Since MR308 allows only one suspension request to be nested, this service call behaves the same way as rsm_tsk and irsm_tsk..(See Figure 3.26).

frsm_tsk

READYstate

Task

READY state

sus_tsk

SUSPENDED

state

WAI TI NG

state

WAITING state

Number of

suspension

requests

WAITING

SUSPENDED

state

0 1 0

Figure 3.26 Forcible wait of a task and forcible resume

• Release task from waiting (rel_wai, irel_wai)

Forcibly frees a task from WAITING state. A task is freed from WAITING state by this service call when it is in one of the following wait states.

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♦ Timeout wait state ♦ Wait state entered by slp_tsk service call (+ timeout included) ♦ Event flag (+ timeout included) wait state ♦ Semaphore (+ timeout included) wait state ♦ Message (+ timeout included) wait state ♦ Data transmission (+ timeout included) wait state ♦ Data reception (+ timeout included) wait state ♦ Fixed–size memory block (+ timeout included) acquisition wait state ♦ Short data transmission (+ timeout included) wait state ♦ Short data reception (+ timeout included) wait state

• Delay task (dly_tsk)

Keeps a task waiting for a finite length of time. Figure 3.27 shows an example in which execution of a task is kept waiting for 10 ms by the dly_tsk service call. The timeout value should be specified in ms units, and not in time tick units.

Chapter 3 Introduction to MR308

dly_tsk(10)

Task

10msec

Figure 3.27 dly_tsk service call

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Chapter 3 Introduction to MR308

3.5.5 Synchronization and Communication Function (Semaphore)

The semaphore is a function executed to coordinate the use of devices and other resources to be shared by several tasks in cases where the tasks simultaneously require the use of them. When, for instance, four tasks simultaneously try to acquire a total of only three communication lines as shown in Figure 3.28, communication line-to-task connections can be made without incurring contention.

Communication

Line

Communication

Line

Communication

Line

Task

Semaphore

Task

Figure 3.28 Exclusive Control by Semaphore

The semaphore has an internal semaphore counter. In accordance with this counter, the semaphore is acquired or released to prevent competition for use of the same resource.(See Figure 3.29).

cquired

Task

Returned after use

Figure 3.29 Semaphore Counter

The MR308 kernel offers the following semaphore synchronization service calls.

• Release Semaphore Resource(sig_sem, isig_sem)

Releases one resource to the semaphore. This service call wakes up a task that is waiting for the semaphores service, or increments the semaphore counter by 1 if no task is waiting for the semaphores service.

• Acquire Semaphore Resource(wai_sem, twai_sem)

Waits for the semaphores service. If the semaphore counter value is 0 (zero), the semaphore cannot be acquired. Therefore, the WAITING state prevails.

• Acquire Semaphore Resource(pol_sem, ipol_sem)

Acquires the semaphore resource. If there is no semaphore resource to acquire, an error code is returned and the WAITING state does not prevail.

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Chapter 3 Introduction to MR308

• Reference Semaphore Status (ref_sem, iref_sem)

Refers the status of the target semaphore. Checks the count value and existence of the wait task for the target semaphore.

Figure 3.30 shows example task execution control provided by the wai_sem and sig_sem service calls.

Task

Semaphore Counter

wai_sem sig_sem

wai_sem

WAI T state

3 2 1 0 0x

Figure 3.30 Task Execution Control by Semaphore

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Chapter 3 Introduction to MR308

3.5.6 Synchronization and Communication Function (Eventflag)

The eventflag is an internal facility of MR308 that is used to synchronize the execution of multiple tasks. The eventflag uses a flag wait pattern and a 16-bit pattern to control task execution. A task is kept waiting until the flag wait conditions set are met.

It is possible to determine whether multiple waiting tasks can be enqueued in one eventflag waiting queue by specifying the eventflag attribute TA_WSGL or TA_WMUL.

Furthermore, it is possible to clear the eventflag bit pattern to 0 when the eventflag meets wait conditions by specifying TA_CLR for the eventflag attribute.

There are following eventflag service calls that are provided by the MR308 kernel.

• Set Eventflag (set_flg, iset_flg)

Sets the eventflag so that a task waiting the eventflag is released from the WAITING state.

• Clear Eventflag (clr_flg, iclr_flg)

Clears the Eventflag.

• Wait for Eventflag (wai_flg, twai_flg)

Waits until the eventflag is set to a certain pattern. There are two modes as listed below in which the eventflag is waited for.

♦ AND wait

Waits until all specified bits are set.

♦ OR wait

Waits until any one of the specified bits is set

• Wait for Eventflag (polling)(pol_flg, ipol_flg)

Examines whether the eventflag is in a certain pattern. In this service call, tasks are not placed in WAITING state.

• Reference Eventflag Status (ref_flg, iref_flg)

Checks the existence of the bit pattern and wait task for the target eventflag.

Figure 3.31 shows an example of task execution control by the eventflag using the wai_flg and set_flg service calls.

The eventflag has a feature that it can wake up multiple tasks collectively at a time.

In Figure 3.31, there are six tasks linked one to another, task A to task F. When the flag pattern is set to 0xF by the set_flg service call, the tasks that meet the wait conditions are removed sequentially from the top of the queue. In this diagram, the tasks that meet the wait conditions are task A, task C, and task E. Out of these tasks, task A, task C, and task E are removed from the queue.

If this event flag has a TA_CLR attribute, when the waiting of Task A is canceled, the bit pattern of the event flag will be set to 0, and Task C and Task E will not be removed from queue.

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Chapter 3 Introduction to MR308

Flag queue Task A Task B Task C

Flag pattern

TaskD

Task E

Task F

set_flg

Flag pattern

0x0F

Wait pattern Wait mo de

0x0F

0xFF

AND

0x0F AND

0xFF AND

Task B

Figure 3.31 Task Execution Control by the Eventflag

0xFF

0x10

Task F Task D

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Chapter 3 Introduction to MR308

3.5.7 Synchronization and Communication Function (Data Queue)

The data queue is a mechanism to perform data communication between tasks. In Figure 3.32, for example, task A can transmit data to the data queue and task B can receive the transmitted data from the data queue.

Data

Data Data

Task A

Figure 3.32 Data queue

Data in width of 32 bits can be transmitted to this data queue.

The data queue has the function to accumulate data. The accumulated data is retrieved in order of FIFO However, the number of data that can be accumulated in the data queue is limited. If data is transmitted to the data queue that is full of data, the service call issuing task goes to a data transmission wait state.

There are following data queue service calls that are provided by the MR308 kernel.

Task B

• Send to Data Queue(snd_dtq, tsnd_dtq)

Transmits data. Namely, data is transmitted to the data queue. If the data queue is full of data, the task goes to a data transmission wait state.

• Send to Data Queue (psnd_dtq, ipsnd_dtq)

Transmits data. Namely, data is transmitted to the data queue. If the data queue is full of data, the task returns error code without going to a data transmission wait state.

• Forced Send to Data Queue (fsnd_dtq, ifsnd_dtq)

Transmits data. Namely, data is transmitted to the data queue. If the data queue is full of data, the data at the top of the data queue or the oldest data is removed, and the transmitted data is stored at the tail of the data queue.

• Receive from Data Queue (rcv_dtq, trcv_dtq)

Receives data. Namely, data is retrieved from the data queue. If the data queue has no data in it, the task is kept waiting until data is transmitted to the data queue.

• Receive from Data Queue (prcv_dtq,iprcv_dtq)

Receives data. Namely, data is received from the data queue. If the data queue has no data in it, the task returns error code without going to a data reception wait state.

• Reference Data Queue Status (ref_dtq,iref_dtq)

Checks to see if there are any tasks waiting for data to be entered in the target data queue and refers to the number of the data in the data queue.

First In First Out

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Chapter 3 Introduction to MR308

3.5.8 Synchronization and Communication Function (Mailbox)

The mailbox is a mechanism to perform data communication between tasks. In Figure 3.33, for example, task A can drop a message into the mailbox and task B can retrieve the message from the mailbox. Since mailbox-based communication is achieved by transferring the beginning address of a message from a task to another, this mode of communication is performed at high speed independently of the message size.

The kernel manages the message queue by means of a link list. The application should prepare a header area that is to be used for a link list. This is called the message header. The message header and the area actually used by the application to store a message are called the message packet. The kernel rewrites the content of the message header as it manages the message queue. The message header cannot be rewritten from the application. The structure of the message queue is shown in Figure 3.34. The message header has its data types defined as shown below.

T_MSG: Mailbox message header

T_MSG_PRI: Mailbox message header with priority included

Messages in any size can be enqueued in the message queue because the header area is reserved on the application side. In no event will tasks be kept waiting for transmission.

Messages can be assigned priority, so that messages will be received in order of priority beginning with the highest. In this case, TA_MPRI should be added to the mailbox attribute. If messages need to be received in order of FIFO, add TA_MFIFO to the mailbox attribute. receive a message, the tasks can be prioritized in which order they can receive a message, beginning with one that has the highest priority. In this case, add TA_TPRI to the mailbox attribute. If tasks are to receive a message in order of FIFO, add TA_TFIFO to the mailbox attribute.

Furthermore, if tasks in a message wait state are to

Message Message

TaskA

Figure 3.33 Mailbox

TaskB

It is in the mailbox definition "message_queue" of the configuration file that the TA_MPRI or TA_MFIFO attribute should be added.

It is in the mailbox definition "wait_queue" of the configuration file that the TA_TPRI or TA_TFIFO attribute should be added.

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Chapter 3 Introduction to MR308

Message

queue

There are following data queue service calls that are provided by the MR308 kernel.

T_MSG header

Message A Message B Message C

Figure 3.34 Message queue

T_MSG header

• Send to Mailbox (snd_mbx, isnd_mbx)

Transmits a message. Namely, a message is dropped into the mailbox.

• Receive from Mailbox (rcv_mbx, trcv_mbx)

Receives a message. Namely, a message is retrieved from the mailbox. At this time, if the mailbox has no messages in it, the task is kept waiting until a message is sent to the mailbox.

T_MSG header

• Receive from Mailbox (polling) (prcv_mbx, iprcv_mbx)

Receives a message. The difference from the rcv_mbx service call is that if the mailbox has no messages in it, the task returns error code without going to a wait state.

• Reference Mailbox Status (ref_mbx, iref_mbx)

Checks to see if there are any tasks waiting for a message to be put into the target mailbox and refers to the message present at the top of the mailbox.

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Chapter 3 Introduction to MR308

3.5.9 Memory pool Management Function

The memorypool management function provides system memory space (RAM space) dynamic control. This function is used to manage a specific memory area (memorypool), dynamically obtain memory blocks from the memorypool as needed for tasks or handlers, and release unnecessary memory blocks to the memorypool. The MR308 supports two types of memorypool management functions, one for fixed-size and the other for variable-size.

Fixed-size Memory pool Management Function

You specify memory block size using configuration file. The MR308 kernel offers the following Fixed-size memory pool management service calls.

• Acquire Fixed-size Memory Block (get_mpf, tget_mpf)

Acquires a memory block from the fixed-size memory pool that has the specified ID. If there are no blank memory blocks in the specified fixed-size memory pool, the task that issued this service call goes to WAITING state and is enqueued in a waiting queue.

• Acquire Fixed-size Memory Block (polling) (pget_mpf, ipget_mpf)

Acquires a memory block from the fixed-size memory pool that has the specified ID. The difference from the get_mpf and tget_mpf service calls is that if there are no blank memory blocks in the memory pool, the task returns error code without going to WAITING state.

Memory Block 1:

Memory Block 2:

Memory Block 3:

Used by TaskA

Used by TaskB

Memory block acquisition request

Memory block acquisition

Memory block acquisition request

No blank memory blocks available

Fixed Length Memorypool

Figure 3.35 Memory Pool Management

• Release Fixed-size Memory Block (rel_mpf, irel_mpf)

Frees the acquired memory block. If there are any tasks in a wait state for the specified fixed-size memory pool, the task enqueued at the top of the waiting queue is assigned the freed memory block. In this case, the task changes its state from WAITING state to READY state. If there are no tasks in a wait state, the memory block is returned to the memory pool.

• Reference Fixed-size Memory Pool Status (ref_mpf, iref_mpf)

Checks the number and the size of blank blocks available in the target memory pool.

TaskC

TaskD

Goes to a wait state

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Chapter 3 Introduction to MR308

Variable-size Memory Pool Management Function

The technique that allows you to arbitrary define the size of memory block acquirable from the memory pool is termed Variable-size scheme. The MR308 manages memory in terms of four fixed-size memory block sizes.

The MR308 calculates the size of individual blocks based on the maximum memory block size to be acquired. You specify the maximum memory block size using the configuration file.

e.g.

variable_memorypool[]{

max_memsize = 400; <---- Maximum size

heap_size = 5000;

};

Defining a variable-size memory pool as shown above causes four fixed-size memory block sizes to become 56 bytes, 112 bytes, 224 bytes, and 448 bytes in compliance with max_memsize.

In the case of user-requested memory, the MR308 performs calculations based on the specified size and selects and allocates the optimum one of four fixed-size memory block sizes. The MR308 cannot allocate a memory block that is not one of the four sizes.

Service calls the MR308 provides include the following.

• Acquire Variable-size Memory Block (pget_mpl)

Round off a block size you specify to the optimal block size among the four block sizes, and acquires memory having the rounded-off size from the memory pool.

The following equations define the block sizes:

a = (((max_memsize+(X-1))/ X × 8)+1) × 8 b = a × 2 c = a × 4 d = a × 8

max_memsize: the value specified in the configuration file X: data size for block control (8 byte)

For example, if you request 200-byte, the MR308 rounds off the size to 244 bytes, and acquires 244-byte memory.

If memory acquirement goes well, the MR308 returns the first address of the memory acquired along with the error code "E_OK". If memory acquirement fails, the MR308 returns the error code "E_TMOUT".

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Chapter 3 Introduction to MR308

200 bytes

TaskA

Rounding

224 bytes

Figure 3.36 pget_mpl processing

• Release Acquire Variable-size Memory Block (rel_mpl)

Releases a acquired memory block by pget_mpl service call.

TaskA

Memorypool

pget_blk

200 bytes

Memorypool

rel_blk

top of

address

Figure 3.37 rel_mpl processing

• Reference Acquire Variable-size Memory Pool Status (ref_mpl, iref_mpl)

Checks the total free area of the memory pool, and the size of the maximum free area that can immediately be acquired.

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3.5.10 Time Management Function

The time management function provides system time management, time reading36, time setup37, and the functions of the alarm handler, which actuates at preselected times, and the cyclic handler, which actuates at preselected time intervals.

The MR308 kernel requires one timer for use as the system clock. There are following time management service calls that are provided by the MR308 kernel. Note, however, that the system clock is not an essential function of MR308. Therefore, if the service calls described below and the time management function of the MR308 are unused, a timer does not need to be occupied for use by MR308.

• Place a task in a finite time wait state by specifying a timeout value

A timeout can be specified in a service call that places the issuing task into WAITING state. service call includes tslp_tsk, twai_flg, twai_sem, tsnd_dtq, trcv_dtq, trcv_mbx, tget_mpf, vtsnd_dtq, and vtrcv_dtq. If the wait cancel condition is not met before the specified timeout time elapses, the error code E_TMOUT is returned, and the task is freed from the wait state. If the wait cancel condition is met, the error code E_OK is returned.

The timeout time should be specified in ms units.

READY state

WAITING state

RUN state

tslp_tsk(50)

Timeout value

tslp_tsk(50)

E_TMOUT

E_OK

This

WAITING state

MR308 guarantees that as stipulated in µITRON specification, timeout processing is not performed until a time equal to or greater than the specified timeout value elapses. More specifically, timeout processing is performed with the following timing.

1. If the timeout value is 0 (for only dly_tsk) The task times out at the first time tick after the service call is issued.

2. If the timeout value is a multiple of time tick interval The timer times out at the (timeout value / time tick interval) + first time tick. For example, if the time tick interval is 10 ms and the specified timeout value is 40 ms, then the timer times out at the fifth occurrence of the time tick. Similarly, if the time tick interval is 5 ms and the specified timeout value is 15 ms, then the timer times out at the fourth occurrence of the time tick.

3. If the timeout value is not a multiple of time tick interval The timer times out at the (timeout value / time tick interval) + second time tick. For example, if the time tick interval is 10 ms and the specified timeout value is 35 ms, then the timer times out

get_tim service call

set_tim service call

SUSPENDED state is not included.

iwup_tsk

Figure 3.38 Timeout Processing

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at the fifth occurrence of the time tick.

• Set System Time (set_tim)

• Reference System Time (get_tim)

The system time indicates an elapsed time from when the system was reset by using 48-bit data. The time is expressed in ms units.

Chapter 3 Introduction to MR308

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3.5.11 Cyclic Handler Function

The cyclic handler is a time event handler that is started every startup cycle after a specified startup phase has elapsed.

The cyclic handler may be started with or without saving the startup phase. In the former case, the cyclic handler is started relative to the point in time at which it was generated. In the latter case, the cyclic handler is started relative to the point in time at which it started operating. Figure 3.39 and Figure 3.40 show typical operations of the cyclic handler.

If the startup cycle is shorter than the time tick interval, the cyclic handler is started only once every time tick supplied (processing equivalent to isig_tim). For example, if the time tick interval is 10 ms and the startup cycle is 3 ms and the cyclic handler has started operating when a time tick is supplied, then the cyclic handler is started every time tick.

Cyclic handler

created

Activation

phase

Activation

cycle

Handler does

not start

Start operating Stop operating

Activation

Handler does

not start

cycle

Handler starts Handler starts

Activation

cycle

Activation

cycle

Handler does

not start

Figure 3.39 Cyclic handler operation in cases where the activation phase is saved

Cyclic handler

created

Activation

phase

Activation

cycle

Handler does

not start

Start operating Stop operating

Handler does

not start

Activation

cycle

Handler starts Handler starts

Activation

cycle

Activation

cycle

Handler does

not start

Figure 3.40 Cyclic handler operation in cases where the activation phase is not saved

• Start Cyclic Handler Operation (sta_cyc, ista_cyc)

Causes the cyclic handler with the specified ID to operational state.

• Stop Cyclic Handler Operation (stp_cyc, istp_cyc)

Causes the cyclic handler with the specified ID to non-operational state.

• Reference Cyclic Handler Status (ref_cyc, iref_cyc)

Refers to the status of the cyclic handler. The operating status of the target cyclic handler and the remaining time before it starts next time are inspected.

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Chapter 3 Introduction to MR308

3.5.12 Alarm Handler Function

The alarm handler is a time event handler that is started only once at a specified time.

Use of the alarm handler makes it possible to perform time-dependent processing. The time of day is specified by a relative time. Figure 3.41 shows a typical operation of the alarm handler.

Alarm handler

created

Start

operating

Activation

time

Handler starts

Start

operating

Stop

operating

Activation

time

Handler does

not start

Figure 3.41 Typical operation of the alarm handler

• Start Alarm Handler Operation (sta_alm, ista_alm)

Causes the alarm handler with the specified ID to operational state.

• Stop alarm Handler Operation (stp_alm, istp_alm)

Causes the alarm handler with the specified ID to non-operational state.

• Reference Alarm Handler Status (ref_alm, iref_alm)

Refers to the status of the alarm handler. The operating status of the target alarm handler and the remaining time before it starts are inspected.

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Chapter 3 Introduction to MR308

3.5.13 System Status Management Function

• Rotate Task Precedence (rot_rdq, irot_rdq)

This service call establishes the TSS (time-sharing system). That is, if the ready queue is rotated at

regular intervals, round robin scheduling required for the TSS is accomplished (See Figure 3.42)

Priority

１

２

３

ｎ

Figure 3.42 Ready Queue Management by rot_rdq System Call

taskA

taskB taskC

taskD taskE taskF

Move the end of the queue

• Reference task ID in the RUNNING state(get_tid, iget_tid)

References the ID number of the task in the RUNNING state. If issued from the handler, TSK_NONE(=0=) is obtained instead of the ID number.

• Lock the CPU (loc_cpu, iloc_cpu)

Places the system into a CPU locked state.

• Unlock the CPU (unl_cpu, iunl_cpu)

Frees the system from a CPU locked state.

• Disable dispatching (dis_dsp)

Places the system into a dispatching disabled state.

• Enable dispatching (ena_dsp)

Frees the system from a dispatching disabled state.

• Reference context (sns_ctx)

Gets the context status of the system.

• Reference CPU state (sns_loc)

Gets the CPU lock status of the system.

• Reference dispatching state (sns_dsp)

Gets the dispatching disable status of the system.

• Reference dispatching pending state (sns_dpn)

Gets the dispatching pending status of the system.

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Chapter 3 Introduction to MR308

3.5.14 Interrupt Management Function

The interrupt management function provides a function to process requested external interrupts in real time.

The interrupt management service calls provided by the MR308 kernel include the following:

• Returns from interrupt handler (ret_int)

The ret_int service call activates the scheduler to switch over tasks as necessary when returning from the interrupt handler. When using the C language, tion. In this case, therefore, there is no need to invoke this service call.

Figure 3.43 shows an interrupt processing flow. Processing a series of operations from task selection to register restoration is called a "scheduler.".

TaskA

Interrupt

, this function is automatically called at completion of the handler func-

Save Registers

Handler Processing

pragma INTHANDLER Declare

(C language)

iwup_tsk

ret_int

Task Selection

TaskB

Restore Registers

Figure 3.43 Interrupt process flow

In the case that the interruput handler is specified by "#pragma INTHANDLER".

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3.5.15 System Configuration Management Function

This function inspects the version information of MR308.

• References Version Information(ref_ver, iref_ver)

The ref_ver service call permits the user to get the version information of MR308. This version information can be obtained in the standardized format of µITRON specification.

3.5.16 Extended Function (Short Data Queue)

The short data queue is a function outside the scope of µITRON 4.0 Specification. The data queue function handles data as consisting of 32 bits, whereas the short data queue handles data as consisting of 16 bits. Both behave the same way except only that the data sizes they handle are different.

• Send to Short Data Queue (vsnd_dtq, vtsnd_dtq)

Transmits data. Namely, data is transmitted to the short data queue. If the short data queue is full of data, the task goes to a data transmission wait state.

• Send to Short Data Queue (vpsnd_dtq, vipsnd_dtq)

Transmits data. Namely, data is transmitted to the short data queue. If the short data queue is full of data, the task returns error code without going to a data transmission wait state.

• Forced Send to Short Data Queue (vfsnd_dtq, vifsnd_dtq)

• Receive from Short Data Queue(vrcv_dtq, vtrcv_dtq)

Receives data. Namely, data is retrieved from the short data queue. If the short data queue has no data in it, the task is kept waiting until data is transmitted to the short data queue.

• Receive from Short Data Queue (vprcv_dtq, viprcv_dtq)

Receives data. Namely, data is received from the short data queue. If the short data queue has no data in it, the task returns error code without going to a data reception wait state.

• Reference Short Data Queue Status (vref_dtq, viref_dtq)

Checks to see if there are any tasks waiting for data to be entered in the target short data queue and refers to the number of the data in the data queue.

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Chapter 3 Introduction to MR308

3.5.17 Extended Function (Reset Function)

The reset function is a function outside the scope of µITRON 4.0 Specification. It initializes the mailbox, data queue, and memory pool, etc.

• Clear Data Queue Area (vrst_dtq)

Initializes the data queue. If there are any tasks waiting for transmission, they are freed from WAITING state and the error code EV_RST is returned.

• Clear Mailbox Area (vrst_mbx)

Initializes the mailbox.

• Clear Fixed-size Memory Pool Area (vrst_mpf)

Initializes the fixed-size memory pool. If there are any tasks in WAITING state, they are freed from the WAITING state and the error code EV_RST is returned.

• Clear Variable-size Memory Pool Area (vrst_mpl)

Initializes the variable length memory pool.

• Clear Short Data Queue Area (vrst_vdtq)

Initializes the short data queue. If there are any tasks waiting for transmission, they are freed from WAITING state and the error code EV_RST is returned.

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Chapter 3 Introduction to MR308

3.5.18 Service calls That Can Be Issued from Task and Handler

Some service calls can be issued from a task, others can be issued from non-task context, and still others can be issued from both. These service calls are listed in Table 3.4.

Table 3.4 List of the service call can be issued from the task and handler

Service Call Task Context

act_tsk

iact_tsk

can_act

ican_act

sta_tsk

ista_tsk

ext_tsk

ter_tsk

chg_pri

ichg_pri

get_pri

iget_pri

ref_tsk

iref_tsk

ref_tst iref_tst slp_tsk

tslp_tsk

wup_tsk

iwup_tsk

can_wup

ican_wup

rel_wai

irel_wai

sus_tsk isus_tsk rsm_tsk

irsm_tsk frsm_tsk

ifrsm_tsk

dly_tsk

o x x o o x x o o x x o o x o x o x x o o x x o o x x o o x x o o x o x o x x o o x x o o x x o o x x o o x x o o x x o o x

Non-task Context

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Chapter 3 Introduction to MR308

Service Call Task Context

sig_sem isig_sem wai_sem

twai_sem

pol_sem

ipol_sem

ref_sem iref_sem

set_flg

iset_flg

clr_flg

iclr_flg

wai_flg

twai_flg

pol_flg

ipol_flg

ref_flg

iref_flg

snd_dtq tsnd_dtq

psnd_dtq

ipsnd_dtq

fsnd_dtq

ifsnd_dtq

rcv_dtq

trcv_dtq

prcv_dtq

iprcv_dtq

ref_dtq

iref_dtq snd_mbx

isnd_mbx

rcv_mbx

trcv_mbx

prcv_mbx

iprcv_mbx

ref_mbx

iref_mbx

o x x o o x o x o x x o o x x o o x x o o x x o o x o x o x x o o x x o o x o x o x x o o x x o o x o x o x x o o x x o o x x o o x o x o x x o o x x o

Non-task Context

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Chapter 3 Introduction to MR308

Service Call Task Context

get_mpf

tget_mpf

pget_mpf

rel_mpf

irel_mpf

ref_mpf iref_mpf

ipget_mpf

pget_mpl

rel_mpl

ref_mpl

iref_mpl

set_tim

iset_tim

get_tim

iget_tim

sta_cyc

ista_cyc

stp_cyc

istp_cyc

ref_cyc iref_cyc sta_alm

ista_alm

stp_alm

istp_alm

ref_alm

iref_alm

rot_rdq

irot_rdq

get_tid iget_tid

loc_cpu

iloc_cpu

unl_cpu

iunl_cpu

dis_dsp

ena_dsp

sns_ctx

sns_loc sns_dsp

sns_dpn

o x o x o x o x x o o x x o x o o x o x o x x o o x x o o x x o o x x o o x x o o x x o o x x o o x x o o x x o o x x o o x x o o x x o o x x o o x o x o o o o o o o o

Non-task Context

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Chapter 3 Introduction to MR308

Service Call Task Context

ref_ver iref_ver

vsnd_dtq

vtsnd_dtq

vpsnd_dtq

vipsnd_dtq

vfsnd_dtq

vifsnd_dtq

vrcv_dtq

vtrcv_dtq

vprcv_dtq

viprcv_dtq

vref_dtq viref_dtq vrst_mpf vrst_mpl

vrst_mbx

vrst_dtq

vrst_vdtq

o x x o o x o x o x x o o x x o o x o x o x x o o x x o o x o x o x o x o x

Non-task Context

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Chapter 4 Applications Development Procedure

Overview

Chapter 4 Applications Development Procedure Overview

4.1 Overview

Application programs for MR308 should generally be developed following the procedure described below.

1. Generating a project

When using HEW40, create a new project using MR308 on HEW.

2. Coding the application program

Write the application program in code form using C or assembly language. If necessary, correct the sample startup program (crt0mr.a30) and section definition file (c_sec.inc or asm_sec.inc).

3. Creating a configuration file

Create a configuration file which has defined in it the task entry address, stack size, etc. by using an editor.

The GUI configurator available for MR308 may be used to create a configuration file.

4. Executing the configurator

From the configuration file, create system data definition files (sys_rom.inc, sys_ram.inc), include files (mr308.inc, kernel_id.h), and a system generation procedure description file (makefile).

5. System generation

Execute the make41 command or execute build on HEW to generate a system.

6. Writing to ROM

Using the ROM programming format file created, write the finished program file into the ROM. Or load it into the debugger to debug.

Figure 4.1 shows a detailed flow of system generation.

It is abbreviation of High-performance Embedded Workshop.

The make command comes the UNIX standard and UNIX compatible.

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Chapter 4 Applications Development Procedure Overview

C standard

Library

C standard header file

Application

C source

C compiler

nc308

HEW

MR308 include file

kernel.h

Application

include file

Application

Assembler source

Relocatable Assembler

as308

Application

object

Configuration file

Include file kernel_id.h

Systemcall file ( .mrc )

Configurator

cfg308

Include file

mr308.inc

Startup program

start.a30, crt0mr.a30

Jamp table file

Create Jamp table utility

mr308tbl

System data definition file

sys_ram.inc, sys_rom.inc

mrtable.a30

MR308

Library

Linkage Editor

ln308

Absolute

module

Load module converter

lmc308

ROM write format

Figure 4.1 MR308 System Generation Detail Flowchart

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Chapter 4 Applications Development Procedure Overview

4.2 Development Procedure Example

This chapter outlines the development procedures on the basis of a typical MR308 application example.

4.2.1 Applications Program Coding

Figure 4.2 shows a program that simulates laser beam printer operations. Let us assume that the file describing the laser beam printer simulation program is named lbp.c. This program consists of the following three tasks and one interrupt handler.

• Main Task

• Image expansion task

• Printer engine task

• Centronics interface interrupt handler

This program uses the following MR308 library functions.

• sta_tsk()

Starts a task. Give the appropriate ID number as the argument to select the task to be activated. When the kernel_id.h file, which is generated by the configurator, is included, it is possible to specify the task by name (character string).

• wai_flg()

• wup_tsk()

• slp_tsk()

• iset_flg()

Waits until the eventflag is set up. In the example, this function is used to wait until one page of data is entered into the buffer via the Centronics interface.

Wakes up a specified task from the WAITING state. This function is used to start the printer engine task.

Causes a task in the RUNNING state to enter the WAITING state. In the example, this function is used to make the printer engine task wait for image expansion.

Sets the eventflag. In the example, this function is used to notify the image expansion task of the completion of one-page data input.

The configurator converts the ID number to the associated name(character string) in accordance with the information entered int the con-

figuration file.

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Chapter 4 Applications Development Procedure Overview

#include <itron.h> #include <kernel.h> #include "kernel_id.h"

void main() /* main task */ { printf("LBP start simulation \n"); sta_tsk(ID_idle,1); /* activate idle task */ sta_tsk(ID_image,1); /* activate image expansion task */ sta_tsk(ID_printer,1); /* activate printer engine task */ } void image() /* activate image expansion task */ { while(1){ wai_flg(ID_pagein,waiptn,TWF_ANDW, &flgptn);/* wait for 1-page input */

printf(" bit map expansion processing \n"); wup_tsk(ID_printer); /* wake up printer engine task */ } } void printer() /* printer engine task */ { while(1){ slp_tsk(); printf(" printer engine operation \n"); } } void sent_in() /* Centronics interface handler */ {

/* Process input from Centronics interface */ if ( /* 1-page input completed */ ) iset_flg(ID_pagein,setptn); }

Figure 4.2 Program Example

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Chapter 4 Applications Development Procedure Overview

4.2.2 Configuration File Preparation

Create a configuration file which has defined in it the task entry address, stack size, etc. Use of the GUI configurator available for MR308 helps to create a configuration file easily without having to learn how to write it.

Figure 4.3 Configuration File Example

shows an example configuration file for a laser beam printer simulation program (filename "lbp.cfg").

// System Definition system{ stack_size = 1024; priority = 5; system_IPL = 4; tick_nume = 10; }; //System Clock Definition clock{ mpu_clock = 20MHz; timer = A0; IPL = 4; }; //Task Definition task[1]{ name = ID_main; entry_address = main(); stack_size = 512; priority = 1; initial_start = ON; }; task[2]{ name = ID_image; entry_address = image(); stack_size = 512; priority = 2; }; task[3]{ name = ID_printer; entry_address = printer(); stack_size = 512; priority = 4; }; task[4]{ name = ID_idle; entry_address = idle(); stack_size = 256; priority = 5; }; //Eventflag Definition flag[1]{ name = pagein; }; //Interrupt Vector Definition interrupt_vector[0x23]{ os_int = YES; entry_address = sent_in(); };

Figure 4.3 Configuration File Example

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Chapter 4 Applications Development Procedure Overview

4.2.3 Configurator Execution

When using HEW, select "Build all," which enables the user to execute the procedures described in 4.2.3, "Executing the Configurator," and 4.2.4, "System Generation."

Execute the configurator cfg308 to generate system data definition files (sys_rom.inc, sys_ram.inc), include files (mr308.inc, kernel_id.h), and a system generation procedure description file (makefile) from the configuration file.

A> cfg308 -mv lbp.cfg

MR308 version ==> V.4.00 Release 01

Figure 4.4 Configurator Execution

4.2.4 System generation

Execute the make command

A> make -f makefile as308 -F -Dtest=1 crt0mr.a30 nc308 -c task.c ln308 @ln308.sub

to generate the system.

Figure 4.5 System Generation

4.2.5 Writing ROM

Using the lmc308 load module converter, convert the absolute module file into a ROM writable format and then write it into ROM. Or read the file into the debugger and debug it.

There are two types of make commands, one of which conforms to the MS-DOS standard, and the other conforms to or is compliant with the UNIX standard. MR308 accepts only the make command that conforms to or is compliant with the UNIX standard. When using MS-DOS, use a UNIX compatible make command (e.g., the make command included with the C compiler from Microsoft Corporation). For details about the usefulness of UNIX compatible make commands, refer to the release notes from Renesas. The description in this chapter is made for the case where a UNIX compatible make command is executed, as an example.

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Chapter 5 Detailed Applications

5.1 Program Coding Procedure in C Language

5.1.1 Task Description Procedure

1. Describe the task as a function.

To register the task for the MR308, enter its function name in the configuration file. When, for instance, the function name "task()" is to be registered as the task ID number 3, proceed as follows.

task[3]{ name = ID_task;

entry_address = task();

stack_size = 100;

priority = 3;

};

2. At the beginning of file, be sure to include "itron.h",”kernel.h” which is in system directory

as well as "kernel_id.h" which is in the current directory. That is, be sure to enter the following two lines at the beginning of file.

#include <itron.h> #include <kernel.h> #include "kernel_id.h"

3. No return value is provided for the task start function. Therefore, declare the task start

function as a void function.

4. A function that is declared to be static cannot be registered as a task.

5. It isn't necessary to describe ext_tsk() at the exit of task start function.

If you exit the task

from the subroutine in task start function, please describe ext_tsk() in the subroutine.

6. It is also possible to describe the task startup function, using the infinite loop.

#include <itron.h> #include <kernel.h> #include "kernel_id.h"

void task(void) {

/* process */

}

Figure 5.1 Example Infinite Loop Task Described in C Language

#include <itron.h> #include <kernel.h> #include "kernel_id.h"

void task(void) { for(;;){ /* process */

} }

Figure 5.2 Example Task Terminating with ext_tsk() Described in C Language

The task is ended by ext_tsk() automatically if #pramga TASK is declared in the MR308. Similarly, it is ended by ext_tsk when returned halfway of the function by return sentence.

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Chapter 5 Detailed Applications

7. To specify a task, use the string written in the task definition item “name” of the configura-

tion file.

wup_tsk(ID_main);

8. To specify an event flag, semaphore, or mailbox, use the respective strings defined in the

configuration file.

For example, if an event flag is defined in the configuration file as shown below,

flag[1]{ name = ID_abc; };

To designate this eventflag, proceed as follows.

set_flg(ID_abc,&setptn);

9. To specify a cyclic or alarm handler, use the string written in the cyclic or alarm handler

definition item “name” of the configuration file.

sta_cyc(ID_cyc);

10. When a task is reactivated by the sta_tsk() service call after it has been terminated by the

ter_tsk() service call, the task itself starts from its initial state.

However, the external variable and static variable are not automatically initialized when the task is started. The external and static variables are initialized only by the startup program (crt0mr.a30), which actuates before MR308 startup.

11. The task executed when the MR308 system starts up is setup.

12. The variable storage classification is described below.

The MR308 treats the C language variables as indicated in Table 5.1.

Table 5.1 C Language Variable Treatment

Variable storage class Treatment

Global Variable Variable shared by all tasks Non-function static variable Variable shared by the tasks in the same file Auto Variable Register Variable Static variable in function

Variable for specific task

The configurator generates the file “kernel_id.h” that is used to convert the ID number of a task into the string to be specified. This means that the #define declaration necessary to convert the string specified in the task definition item “name” into the ID number of the task is made in “kernel_id.h.” The same applies to the cyclic and alarm handlers.

The task starts from its start function with the initial priority in a wakeup counter cleared state.

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Chapter 5 Detailed Applications

5.1.2 Writing a Kernel (OS Dependent) Interrupt Handler

When describing the kernel (OS-dependent) interrupt handler in C language, observe the following precautions.

1. Describe the kernel(OS-dependent) interrupt handler as a function

2. Be sure to use the void type to declare the interrupt handler start function return value and

argument.

3. At the beginning of file, be sure to include "itron.h",”kernel.h” which is in the system di-

rectory as well as "kernel_id.h" which is in the current directory.

4. Do not use

the ret_int service call in the interrupt handler.48

5. The static declared functions can not be registered as an interrupt handler.

#include <itron.h> #include <kernel.h> #include "kernel_id.h"

void inthand(void)

{ /* process */

iwup_tsk(ID_main); }

Figure 5.3 Example of Kernel(OS-dependent) Interrupt Handler

A configuration file is used to define the relationship between handlers and functions.

When an kernel(OS-dependent) interrupt handler is declared with #pragma INTHANDLER ,code for the ret_int service call is automatically generated.

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Chapter 5 Detailed Applications

5.1.3 Writing Non-kernel (OS-independent ) Interrupt Handler

When describing the non-kernel(OS-independent) interrupt handler in C language, observe the following precautions.

1. Be sure to declare the return value and argument of the interrupt handler start function as

a void type.

2. No service call can be issued from a non-kernel(an OS-independent) interrupt handler.

NOTE: If this restriction is not observed, the software may malfunction.

3. A function that is declared to be static cannot be registered as an interrupt handler.

4. If you want multiple interrupts to be enabled in a non-kernel(an OS-independent) interrupt

handler, always make sure that the non-kernel(OS-independent) interrupt handler is assigned a priority level higher than other kernel(OS-dependent) interrupt handlers.49

#include <itron.h> #include <kernel.h> #include "kernel_id.h"

void inthand(void) { /* process */ }

Figure 5.4 Example of Non-kernel(OS-independent) Interrupt Handler

If you want the non-kernel(OS-independent) interrupt handler to be assigned a priority level lower than kernel(OS-dependent) interrupt handlers, change the description of the non-kernel(OS-independent) interrupt handler to that of the kernel (OS-dependent) interrupt handler.

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Chapter 5 Detailed Applications

5.1.4 Writing Cyclic Handler/Alarm Handler

When describing the cyclic or alarm handler in C language, observe the following precautions.

1. Describe the cyclic or alarm handler as a function.50

2. Be sure to declare the return value and argument of the interrupt handler start function as

a void type.

3. At the beginning of file, be sure to include "itron.h",”kernel.h” which is in the system di-

rectory as well as "kernel_id.h" which is in the current directory.

4. The static declared functions cannot be registered as a cyclic handler or alarm handler.

5. The cyclic handler and alarm handler are invoked by a subroutine call from a system clock

interrupt handler.

#include <itron.h> #include <kernel.h> #include "kernel_id.h"

void cychand(void) { /*process */ }

Figure 5.5 Example Cyclic Handler Written in C Language

The handler-to-function name correlation is determined by the configuration file.

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Chapter 5 Detailed Applications

5.2 Program Coding Procedure in Assembly Language

This section describes how to write an application using the assembly language.

5.2.1 Writing Task

This section describes how to write an application using the assembly language.

1. Be sure to include "mr308.inc" at the beginning of file.

2. For the symbol indicating the task start address, make the external declaration.

3. Be sure that an infinite loop is formed for the task or the task is terminated by the ext_tsk

service call.

.INCLUDE mr308.inc ----- (1) .GLB task ----- (2)

task: ; process jmp task ----- (3)

Figure 5.6 Example Infinite Loop Task Described in Assembly Language

.INCLUDE mr308.inc .GLB task

task: ; process ext_tsk

Figure 5.7 Example Task Terminating with ext_tsk Described in Assembly Language

4. The initial register values at task startup are indeterminate except the PC, SB, R0 and FLG

registers.

5. To specify a task, use the string written in the task definition item “name” of the configura-

tion file.

wup_tsk #ID_task

6. To specify an event flag, semaphore, or mailbox, use the respective strings defined in the

configuration file.

For example, if a semaphore is defined in the configuration file as shown below,:

semaphore[1]{ name = abc; };

To specify this semaphore, write your specification as follows:

sig_sem #ID_abc

7. To specify a cyclic or alarm handler, use the string written in the cyclic or alarm handler

definition item “name” of the configuration file

For example, if you want to specify a cyclic handler "cyc," write your specification as follows:

sta_cyc #ID_cyc

Use the .GLB pseudo-directive

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Chapter 5 Detailed Applications

8. Set a task that is activated at MR308 system startup in the configuration file

The relationship between task ID numbers and tasks(program) is defined in the configuration file.

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Chapter 5 Detailed Applications

5.2.2 Writing Kernel(OS-dependent) Interrupt Handler

When describing the kernel(OS-dependent) interrupt handler in assembly language, observe the following precautions

1. At the beginning of file, be sure to include "mr308.inc" which is in the system directory.

2. For the symbol indicating the interrupt handler start address, make the external declara-

tion(Global declaration).

3. Make sure that the registers used in a handler are saved at the entry and are restored after

use.

4. Return to the task by ret_int service call.

inth:

.INCLUDE mr308.inc ------(1) .GLB inth ------(2)

; Registers used are saved to a stack ------(3) iwup_tsk #ID_task1

: process :

; Registers used are restored ------(3)

ret_int ------(4)

Figure 5.8 Example of kernel(OS-depend) interrupt handler

Use the .GLB peudo-directive.

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Chapter 5 Detailed Applications

5.2.3 Writing Non-kernel(OS-independent) Interrupt Handler

1. For the symbol indicating the interrupt handler start address, make the external declaration

(public declaration).

2. Make sure that the registers used in a handler are saved at the entry and are restored after

use.

3. Be sure to end the handler by REIT instruction.

4. No service calls can be issued from a non-kernel(an OS-independent) interrupt handler.

NOTE: If this restriction is not observed, the software may malfunction.

5. If you want multiple interrupts to be enabled in a non-kernel(an OS-independent) interrupt

handler, always make sure that the non-kernel(OS-independent) interrupt handler is assigned a priority level higher than other non-kernel(OS-dependent) interrupt handlers.

.GLB inthand ----- (1)

inthand:

; Registers used are saved to a stack ----- (2) ; interrupt process ; Registers used are restored ----- (2) REIT ----- (3)

Figure 5.9 Example of Non-kernel(OS-independent) Interrupt Handler of Specific Level

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Chapter 5 Detailed Applications

5.2.4 Writing Cyclic Handler/Alarm Handler

When describing the cyclic or alarm handler in Assembly Language, observe the following precautions.

1. At the beginning of file, be sure to include "mr308.inc" which is in the system directory.

2. For the symbol indicating the handler start address, make the external declaration.

3. Always use the RTS instruction (subroutine return instruction) to return from cyclic han-

dlers and alarm handlers.

For examples:

.INCLUDE mr308.inc ----- (1) .GLB cychand ----- (2)

cychand:

; handler process

rts ----- (3)

Figure 5.10 Example Handler Written in Assembly Language

Use the .GLB pseudo-directive.

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Chapter 5 Detailed Applications

5.3 The Use of INT Instruction

MR308 has INT instruction interrupt numbers reserved for issuing service calls as listed in Table 5.2. For this reason, when using software interrupts in a user application, do not use interrupt numbers 63 through 55 and be sure to use some other numbers.

Table 5.2 Interrupt Number Assignment

Interrupt No. Service calls Used

63 Service calls that can be issued from only task context 62 Service calls that can be issued from only non-task context.

Service calls that can be issued from both task context and non-task context. 61 ret_int service call 60 dis_dsp service call 59 loc_cpu, iloc_cpu service call 58 ext_tsk service call 55 tsnd_dtq, twai_flg, vtsnd_dtq service call

5.4 The Use of registers of bank

The registers of bank is 0, when a task starts on MR308.

MR308 does not change the registers of bank in processing kernel.

You must pay attention to the followings.

• Don’t change the regisers of bank in processing a task.

• If an interrupt handler with regisers of bank 1 have multiple interrupts of an interrupt handler with regis-

ers of bank 1 , the program can not execute normally.

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Chapter 5 Detailed Applications

5.5 Regarding Interrupts

5.5.1 Types of Interrupt Handlers

MR308's interrupt handlers consist of kernel(OS-dependent) interrupt handlers and non-kernel (OS-independent) interrupt handlers.

The following shows the definition of each type of interrupt handler.

• Kernel(OS-dependent) interrupt handler

The kernel(OS-dependent) interrupt handler is defined as one that satisfies one of the following two conditions:

♦ Interrupt handlers issuing a service call

♦ Interrupt handlers including multiple interrupt handlers issuing a service call

The kernel(OS-dependent) interrupt handler's IPL value must be below the kernel mask level (OS interrupt disable level = system.IPL ). IPL = 0 to system.IPL

• Non-kernel(OS-independent) interrupt handler

The non-kernel(OS-independent) interrupt handler is defined as one that satisfies both of the following two conditions:

♦ Interrupt handlers not issuing a service call

♦ Interrupt handlers that do not have multiple interrupts of interrupt handlers issuing a service call

(system clock interrupt handler)

The non-kernel(OS-independent) interrupt handler's IPL value must be between (system.IPL + 1) to 7. Namely, the non-kernel(OS-independent) interrupt handler's IPL value cannot be set below the kernel(OS-independent) interrupt disable level.

Figure 5.11 shows the relationship between the non-kernel(OS-independent) interrupt handlers and kernel(OS-dependent) interrupt handlers where the kernel mask level(OS interrupt disable level) is set to 3.

Kernel mask level

(OS Interrupt disable level)

Low

High

0 1 2 3 4 5 6 7

Kernel

(OS-dependent)

Interrupt handler

Figure 5.11 Interrupt handler IPLs

Non-kernel (OS-independent) Interrupt handler

5.5.2 The Use of Non-maskable Interrupt

An NMI interrupt and Watchdog Timer interrupt have to use be a non-kernel(OS independent) interrupt handler. If they are a kernel(OS dependent) interrupt handler, the program will not work normally.

system.IPL is set by the configuration file.

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Chapter 5 Detailed Applications

5.5.3 Controlling Interrupts

Interrupt enable/disable control in a service call is accomplished by IPL manipulation. The IPL value in a service call is set to the kernel mask level(OS interrupt disable level = system.IPL) in order to disable interrupts for the kernel(OS-dependent) interrupt handler. In sections where all interrupts can be enabled, it is returned to the initial IPL value when the service call was invoked.

Figure 5.12 Interrupt control in a System Call that can be Issued from only a Task

shows the interrupt enable flag and IPL status in a service call.

• For service calls that can be issued from only task context.

When the I flag before issuing a service call is 1.

Task Service call issued

I flag

IPL

When the I flag before issuing a service call is 0.

Task Service call issued

I flag

IPL

0 system.IPL system.IPL

Service call processing

1 0

Service call processing

1 0

Figure 5.12 Interrupt control in a System Call that can be Issued from only a Task

• For service calls that can be issued from only non-task context or from both task context and non-task

context.

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Chapter 5 Detailed Applications

When the I flag before issuing a service call is 1

Task or Handler

I flag

IPL

When the I flag before issuing a service call is 0

Task or Handler

I flag

IPL

Service call issued

4 system.IPL system.IPL

Service call issued

4 system.IPL system.IPL

service call processing

1 0

0 0

Task or Handler

Figure 5.13 Interrupt control in a System Call that can be Issued from a Task-independent

As shown in Figure 5.12 Interrupt control in a System Call that can be Issued from only a Task

Task or Handler

and Figure 5.13 Interrupt control in a System Call that can be Issued from a Task-independent

, the interrupt enable flag and IPL change in a service call. For this reason, if you want to disable interrupts in a user application, Renesas does not recommend using the method for manipulating the interrupt disable flag and IPL to disable the interrupts.

The following two methods for interrupt control are recommended:

1. Modify the interrupt control register (SFR) for the interrupt you want to be disabled.

2. Use service calls loc_cpu and unl_cpu.

The interrupts that can be controlled by the loc_cpu service call are only the kernel(OS-dependent) interrupt. Use method 1 to control the non-kernel(OS-independent) interrupts.

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Chapter 5 Detailed Applications

5.6 Regarding Delay Dispatching

MR308 has four service calls related to delay dispatching.

• dis_dsp

• ena_dsp

• loc_cpu

• unl_cpu

The following describes task handling when dispatch is temporarily delayed by using these service calls.

1. When the execution task in delay dispatching is preempted

While dispatch is disabled, even under conditions where the task under execution should be preempted, no time is dispatched to new tasks that are in an executable state. Dispatching to the tasks to be executed is delayed until the dispatch disabled state is cleared. When dispatch is being delayed.

• Task under execution is in a RUNNING state and is linked to the ready queue

• Task to be executed after the dispatch disabled state is cleared is in a READY state and is linked to the

highest priority ready queue (among the queued tasks).

2. isus_tsk,irsm_tsk during dispatch delay

In cases when isus_tsk is issued from an interrupt handler that has been invoked in a dispatch disabled state to the task under execution (a task to which dis_dsp was issued) to place it in a SUSPENDED state. During delay dispatching.

• The task under execution is handled inside the OS as having had its delay dispatching cleared. For this

reason, in isus_tsk that has been issued to the task under execution, the task is removed from the ready queue and placed in a SUSPENDED state. Error code E_OK is returned. Then, when irsm_tsk is issued to the task under execution, the task is linked to the ready queue and error code E_OK is returned. However, tasks are not switched over until delay dispatching is cleared.

• The task to be executed after disabled dispatching is re-enabled is linked to the ready queue.

3. rot_rdq, irot_rdq during dispatch delay

When rot_rdq (TPRI_RUN = 0) is issued during dispatch delay, the ready queue of the own task's priority is rotated. Also, when irot_rdq (TPRI_RUN = 0) is issued, the ready queue of the executed task's priority is rotated. In this case, the task under execution may not always be linked to the ready queue. (Such as when isus_tsk is issued to the executed task during dispatch delay.)

4. Precautions

• No service call (e.g., slp_tsk, wai_sem) can be issued that may place the own task in a wait state while

in a state where dispatch is disabled by dis_dsp or loc_cpu.

• Note that ena_dsp and dis_dsp cannot be issued while the system is placed in a CPU locked state by

loc_cpu.

• Disabled dispatch is re-enabled by issuing ena_dsp once after issuing dis_dsp several times.

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Chapter 5 Detailed Applications

5.7 Regarding Initially Activated Task

MR308 permits the user to specify a task that starts from a READY state at system startup time. To do this, add TA_STA as task attribute. This specification should be set in a configuration file.

For details on how to set, refer to page - 105 -.

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Chapter 5 Detailed Applications

5.8 Modifying MR308 Startup Program

MR308 comes with two types of startup programs as described below.

• start.a30

This startup program is used when you created a program using the assembly language.

• crt0mr.a30

This startup program is used when you created a program using the C language.

This program is derived from "start.a30" by adding an initialization routine in C language.

The startup programs perform the following:

• Initialize the processor after a reset.

• Initialize C language variables (crt0mr.a30 only).

• Set the system timer.

• Initialize MR308's data area.

Copy these startup programs from the directory indicated by environment variable "LIB308" to the current directory.If necessary, correct or add the sections below:

When using HEW, the user can choose to automatically generate a sample during project generation or use an already created one.

• Setting processor mode register

Set a processor mode matched to your system to the processor mode register.

• Adding user-required initialization program

To add an initialization program needed for the user, add it at a place immediately preceding the initialization of standard input/output functions in the C language startup program (crt0mr.a30).

If the standard input/output functions are unused, make the relevant part a comment.

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Chapter 5 Detailed Applications

5.8.1 C Language Startup Program (crt0mr.a30)

Figure 5.14 C Language Startup Program (crt0mr.a30)

shows the C language startup program(crt0mr.a30).

1 ;**************************************************************** 2 ; 3 ; MR308 start up program for C language 4 ; COPYRIGHT(C) 2003 RENESAS TECHNOLOGY CORPORATION 5 ; AND RENESAS SOLUTIONS CORPORATION ALL RIGHTS RESERVED 6 ; MR308 V.1.10 Release 1 7 ; 8 ; ****************************************************************

9 ; "$Id: crt0mr.a30,v 1.1 2005/05/20 06:28:47 inui Exp $" 10 ;*A1* 2005-02-28 for ES 11 ; 12 .LIST OFF 13 .INCLUDE c_sec.inc 14 .INCLUDE mr308.inc 15 .INCLUDE sys_rom.inc 16 .INCLUDE sys_ram.inc 17 .LIST ON 18 19 .GLB __SYS_INITIAL 20 .GLB __END_INIT 21 .GLB __init_sys,__init_tsk 22 23 .IF M16C70!=0 24 regoffset .EQU -0220H 25 .ELSE 26 regoffset .EQU 0 27 .ENDIF 28 29 ;----------------------------------------------------------------30 ; SBDATA area definition 31 ;----------------------------------------------------------------32 .GLB __SB__ 33 .SB __SB__ 34 35 ;================================================================= 36 ; Initialize Macro declaration 37 ;----------------------------------------------------------------38 N_BZERO .MACRO TOP_,SECT_ 39 MOV.B #00H, R0L 40 MOV.L #TOP_, A1 41 MOV.W #sizeof SECT_, R3 42 SSTR.B 43 .ENDM 44 45 N_BCOPY .MACRO FROM_,TO_,SECT_ 46 MOV.L #FROM_,A0 47 MOV.L #TO_,A1 48 MOV.W #sizeof SECT_, R3 49 SMOVF.B 50 .ENDM 51 52 BZERO .MACRO TOP_,SECT_ 53 .local _end, _loop 54 55 MOV.L #TOP_, A1 56 MOV.B #00H, R0L 57 MOV.L #(sizeof SECT_ & 0FFFFFFH), R3R1 58 XCHG.W R1,R3 59 _loop: 60 SSTR.B 61 CMP.W #0,R1 62 JEQ _end 63 MOV.B R0L,[A1] 64 ADD.L #1,A1 65 MOV.W #0FFFFH,R3 66 SUB.W #1,R1 67 JMP _loop 68

_end: 69 .ENDM 70 71 BCOPY .MACRO FROM_,TO_,SECT_ 72 .local _end, _loop

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Chapter 5 Detailed Applications

73 74 MOV.L #FROM_,A0 75 MOV.L #TO_,A1 76 MOV.L #(sizeof SECT_ & 0FFFFFFH), R3R1 77 XCHG.W R1,R3 78 _loop: 79 SMOVF.B 80 CMP.W #0,R1 81 JEQ _end 82 MOV.B [A0],[A1] 83 ADD.L #1,A1 84 ADD.L #1,A0 85 MOV.W #0FFFFH,R3 86 SUB.W #1,R1 87 JMP _loop 88 _end: 89 .ENDM 90 91 ;================================================================= 92 ; Interrupt section start 93 ;----------------------------------------------------------------94 .SECTION MR_KERNEL,CODE,ALIGN 95 96 ;----------------------------------------------------------------97 ; after reset,this program will start 98 ;----------------------------------------------------------------99 __SYS_INITIAL:

100 LDC #__Sys_Sp,ISP ; set initial ISP 101 102 MOV.B #2,0AH 103 MOV.B #00,PMOD ; Set Processor Mode Register 104 MOV.B #0,0AH 105 LDC #0010H,FLG 106 LDC #__SB__,SB 107 LDC #0000H,FLG 108 LDC #__Sys_Sp,FB 109 LDC #__SB__,SB 110 111 ; +-----------------------------------------------------+ 112 ; | ISSUE SYSTEM CALL DATA INITIALIZE | 113 ; +-----------------------------------------------------+ 114 ; For PD308 115 __INIT_ISSUE_SYSCALL 116 117 ;================================================================= 118 ; MR_RAM zero clear 119 ;-------------------------------------------------------120 N_BZERO MR_RAM_NE_top,MR_RAM_NE 121 N_BZERO MR_RAM_NO_top,MR_RAM_NO 122 BZERO MR_RAM_top,MR_RAM 123 124 ;================================================================= 125 ; NEAR area initialize. 126 ;-------------------------------------------------------127 ; bss zero clear 128 ;-------------------------------------------------------129 N_BZERO bss_SE_top,bss_SE 130 N_BZERO bss_SO_top,bss_SO 131 132 N_BZERO bss_NE_top,bss_NE 133 N_BZERO bss_NO_top,bss_NO 134 135 ;-------------------------------------------------------136 ; initialize data section 137 ;-------------------------------------------------------138 N_BCOPY data_SEI_top,data_SE_top,data_SE 139 N_BCOPY data_SOI_top,data_SO_top,data_SO 140

N_BCOPY data_NEI_top,data_NE_top,data_NE

141 N_BCOPY data_NOI_top,data_NO_top,data_NO 142 143 ;================================================================= 144 ; FAR area initialize. 145 ;-------------------------------------------------------146 ; bss zero clear 147 ;-------------------------------------------------------148 BZERO bss_FE_top,bss_FE 149 BZERO bss_FO_top,bss_FO 150 151 ;-------------------------------------------------------152 ; Copy edata_E(O) section from edata_EI(OI) section

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Chapter 5 Detailed Applications

153 ;-------------------------------------------------------154 BCOPY data_FEI_top,data_FE_top,data_FE 155 BCOPY data_FOI_top,data_FO_top,data_FO 156 157 LDC #__Sys_Sp,SP 158 LDC #__Sys_Sp,FB 159 160 161 ;----------------------------------------------------------------162 ; Set System IPL and Set Interrupt Vector 163 ;----------------------------------------------------------------164 MOV.B #0,R0L 165 MOV.B #__SYS_IPL,R0H 166 LDC R0,FLG 167 LDC #__INT_VECTOR,INTB 168 169 ; +-----------------------------------------------------+ 170 ; | System timer interrupt setting | 171 ; +-----------------------------------------------------+ 172 .IF USE_TIMER 173 MOV.B #stmr_mod_val,stmr_mod_reg+regoffset ; set timer mode 174 MOV.W #stmr_cnt,stmr_ctr_reg+regoffset ; set interval count 175 MOV.B #stmr_int_IPL,stmr_int_reg ; set timer IPL 176 OR.B #stmr_bit+1,stmr_start+regoffset ; system timer start 177 .ENDIF 178 179 ; +-----------------------------------------------------+ 180 ; | System timer initialize | 181 ; +-----------------------------------------------------+ 182 .IF USE_SYSTEM_TIME 183 MOV.W #__D_Sys_TIME_L,__Sys_time+4 184 MOV.W #__D_Sys_TIME_M,__Sys_time+2 185 MOV.W #__D_Sys_TIME_H,__Sys_time 186 .ENDIF 187 188 ; +-----------------------------------------------------+ 189 ; | User Initial Routine ( if there are ) | 190 ; +-----------------------------------------------------+ 191 ; Initialize standard I/O 192 .GLB _init 193 JSR.A _init 194 195 ; +-----------------------------------------------------+ 196 ; | Initalization of System Data Area | 197 ; +-----------------------------------------------------+ 198 JSR.W __init_sys 199 JSR.W __init_tsk 200 201 .IF __MR_TIMEOUT 202 .GLB __init_tout 203 JSR.W __init_tout 204 .ENDIF 205 206 .IF __NUM_FLG 207 .GLB __init_flg 208 JSR.W __init_flg 209 .ENDIF 210 211 .IF __NUM_SEM 212 .GLB __init_sem 213 JSR.W __init_sem 214 .ENDIF 215 216 .IF __NUM_DTQ 217 .GLB __init_dtq 218 JSR.W __init_dtq 219 .ENDIF 220 221 .IF __NUM_VDTQ ;*A1* 222 .GLB __init_vdtq 223 JSR.W __init_vdtq 224 .ENDIF 225 226 .IF __NUM_MBX 227 .GLB __init_mbx 228 JSR.W __init_mbx 229 .ENDIF 230 231 .IF ALARM_HANDLER 232 .GLB __init_alh

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Chapter 5 Detailed Applications

233 JSR.W __init_alh 234 .ENDIF 235 236 .IF CYCLIC_HANDLER 237 .GLB __init_cyh 238 JSR.W __init_cyh 239 .ENDIF 240 241 .IF __NUM_MPF ;*A1* 242 ; Fixed Memory Pool 243 .GLB __init_mpf 244 JSR.W __init_mpf 245 .ENDIF 246 247 .IF __NUM_MPL ;*A1* 248 ; Variable Memory Pool 249 .GLB __init_mpl 250 JSR.W __init_mpl 251 .ENDIF 252 253 ; For PD308 254 __LAST_INITIAL 255 256 __END_INIT: 257 258 ; +-----------------------------------------------------+ 259 ; | Start initial active task | 260 ; +-----------------------------------------------------+ 261 __START_TASK 262 263 .GLB __rdyq_search 264 JMP.W __rdyq_search 265 266 ; +---------------------------------------------+ 267 ; | Define Dummy | 268 ; +---------------------------------------------+ 269 .GLB __SYS_DMY_INH 270 __SYS_DMY_INH: 271 REIT 272 273 .IF CUSTOM_SYS_END 274 ; +---------------------------------------------+ 275 ; | Syscall exit rouitne to customize 276 ; +---------------------------------------------+ 277 .GLB __sys_end 278 __sys_end: 279 ; Customize here. 280 REIT 281 .ENDIF 282 283 ; +---------------------------------------------+ 284 ; | exit() function | 285 ; +---------------------------------------------+ 286 .GLB _exit,$exit 287 _exit: 288 $exit: 289 JMP _exit 290 291 .IF USE_TIMER 292 ; +---------------------------------------------+ 293 ; | System clock interrupt handler | 294 ; +---------------------------------------------+ 295 .GLB __SYS_STMR_INH 296 .ALIGN 297 __SYS_STMR_INH: 298 ; process issue system call 299 ; For PD308 300

__ISSUE_SYSCALL

301 302 ; System timer interrupt handler 303 _STMR_hdr 304 305 ret_int 306 .ENDIF

Figure 5.14 C Language Startup Program (crt0mr.a30)

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Chapter 5 Detailed Applications

The following explains the content of the C language startup program (crt0mr.a30).

1. Incorporate a section definition file [13 in Figure 5.14]

2. Incorporate an include file for MR308 [14 in Figure 5.14]

3. Incorporate a system ROM area definition file [15 in Figure 5.14]

4. Incorporate a system RAM area definition file [16 in Figure 5.14]

5. This is the initialization program __SYS_INITIAL that is activated immediately after a reset. [99 - 256 in Figure 5.14]

♦ Setting the System Stack pointer [100 in Figure 5.14] ♦ Setting the processor mode register [102 - 104 in Figure 5.14] ♦ Setting the SB,FB register [105 - 109 in Figure 5.14] ♦ Initial set the C language. [129 - 155 in Figure 5.14] When using no standard input/output func-

tions, remove the lines 191 and 192 in Figure 5.14.

♦ Setting OS interrupt disable level [164 - 166 in Figure 5.14] ♦ Setting the address of interrupt vector table [167 in Figure 5.14] ♦ Set MR308's system clock interrupt [172-177 in Figure 5.14] ♦ Initial set MR308's system timer [182-186 in Figure 5.14]

6. Initial set parameters inherent in the application [191 in Figure 5.14]

7. Initialize the RAM data used by MR308 [198-251 in Figure 5.14]

8. Activate the initial startup task. [254 in Figure 5.14]

9. This is a system clock interrupt handler [295-306 in Figure 5.14]

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Chapter 5 Detailed Applications

5.9 Memory Allocation

This section describes how memory is allocated for the application program data.

Use the section file provided by MR308 to set memory allocation.

MR308 comes with the following two types of section files:

• asm_sec.inc

This file is used when you developed your applications with the assembly language.

Refer to page - 91 - for details about each section.

• c_sec.inc

This file is used when you developed your applications with the C language.

c_sec.inc is derived from "asm_sec.inc" by adding sections generated by C compiler NC308.

Refer to page - 92 - for details about each section.

Modify the section allocation and start address settings in this file to suit your system.

The following shows how to modify the section file.

e.g.

If you want to change the program section start address from F0000H to F1000H .section program .org 0F0000H ; Correct this address to F1000H

.section program

.org 0F1000H ;

↓

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Renesas 70 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Chapter 1 User’s Manual Organization

Chapter 2 General Information

Chapter 3 Introduction to MR308

3.1.1 Why Real-time OS is Necessary

Service call Task switching

3.2.1 Service Call Processing

3.2.2 Task Designation in Service call

Task

3.3.2 Task Priority and Ready Queue

3.3.3 Task Priority and Waiting Queue

3.3.4 Task Control Block(TCB)

3.4.1 Task Context and Non-task Context

3.4.3 CPU Locked/Unlocked States

3.5.3 Task Management Function

3.5.4 Synchronization functions attached to task

3.5.5 Synchronization and Communication Function (Semaphore)

3.5.6 Synchronization and Communication Function (Eventflag)

3.5.7 Synchronization and Communication Function (Data Queue)

3.5.8 Synchronization and Communication Function (Mailbox)

3.5.9 Memory pool Management Function

Fixed-size Memory pool Management Function

Variable-size Memory Pool Management Function

3.5.10 Time Management Function

3.5.11 Cyclic Handler Function

3.5.12 Alarm Handler Function

3.5.13 System Status Management Function

3.5.15 System Configuration Management Function

3.5.16 Extended Function (Short Data Queue)

3.5.17 Extended Function (Reset Function)

3.5.18 Service calls That Can Be Issued from Task and Handler

4.2.1 Applications Program Coding

4.2.2 Configuration File Preparation

Chapter 5 Detailed Applications

5.1.1 Task Description Procedure

5.1.2 Writing a Kernel (OS Dependent) Interrupt Handler

5.1.3 Writing Non-kernel (OS-independent ) Interrupt Handler

5.1.4 Writing Cyclic Handler/Alarm Handler

5.2.2 Writing Kernel(OS-dependent) Interrupt Handler

5.2.4 Writing Cyclic Handler/Alarm Handler

5.5.1 Types of Interrupt Handlers

5.5.2 The Use of Non-maskable Interrupt

5.8.1 C Language Startup Program (crt0mr.a30)