Digi LP3500 User manual

Type
User manual
Integrated C Development System
For Rabbit
2000 and 3000 Microprocessors
Users Manual
019-0125_K
Dynamic C Users Manual
©2011 Digi International® Inc.
All rights reserved.
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The latest revision of this manual is available at www.digi.com.
Dynamic C Users Manual digi.com 3
Table of Contents
1. Installing Dynamic C ......................................... 9
1.1 Requirements .............................................. 9
1.2 Assumptions ............................................... 9
2. Introduction to Dynamic C.............................. 11
2.1 The Nature of Dynamic C ........................ 11
2.1.1 Speed............................................ 11
2.2 Dynamic C Enhancements and Differences .
12
2.3 Rabbit and Z180 Comparison................... 14
3. Quick Tutorial ................................................... 15
3.1 Run DEMO1.C ......................................... 16
3.1.1 Single Stepping ............................ 17
3.1.2 Watch Expression......................... 17
3.1.3 Breakpoint.................................... 17
3.1.4 Editing the Program ..................... 18
3.2 Run DEMO2.C ......................................... 18
3.2.1 Watching Variables Dynamically. 18
3.3 Run DEMO3.C ......................................... 19
3.3.1 Cooperative Multitasking............. 19
3.4 Run DEMO4.C ......................................... 20
3.4.1 Trace Macros................................ 21
3.5 Summary of Features................................ 22
4. Language............................................................ 23
4.1 C Language Elements............................... 23
4.2 Punctuation Tokens................................... 24
4.3 Data........................................................... 25
4.3.1 Data Type Limits.......................... 25
4.4 Names ....................................................... 26
4.5 Macros ...................................................... 27
4.5.1 Macro Operators # and ##............ 27
4.5.2 Nested Macro Definitions ............ 28
4.5.3 Macro Restrictions ....................... 29
4.6 Numbers.................................................... 29
4.7 Strings and Character Data ....................... 30
4.7.1 String Concatenation.................... 30
4.7.2 Character Constants ..................... 31
4.8 Statements................................................. 32
4.9 Declarations .............................................. 32
4.10 Functions.................................................. 33
4.11 Prototypes................................................. 33
4.12 Type Definitions....................................... 34
4.13 Aggregate Data Types.............................. 35
4.13.1 Array .......................................... 35
4.13.2 Structure ..................................... 36
4.13.3 Union.......................................... 36
4.13.4 Composites................................. 36
4.14 Storage Classes ........................................ 37
4.15 Pointers .................................................... 37
4.16 Pointers to Functions, Indirect Calls........ 38
4.17 Argument Passing.................................... 39
4.18 Program Flow .......................................... 40
4.18.1 Loops ......................................... 40
4.18.2 Continue and Break ................... 41
4.18.3 Branching................................... 42
4.19 Function Chaining ................................... 44
4.20 Global Initialization................................. 45
4.21 Libraries................................................... 46
4.21.1 LIB.DIR ..................................... 47
4.22 Headers .................................................... 47
4.23 Modules ................................................... 47
4.23.1 The Parts of a Module................ 48
4.23.2 Module Sample Code................. 50
4.23.3 Important Notes ......................... 51
4.24 Function Description Headers ................. 52
4.25 Support Files............................................ 52
5. Multitasking with Dynamic C ........................ 53
5.1 Cooperative Multitasking ......................... 53
5.2 A Real-Time Problem............................... 54
5.2.1 Solving the Real-Time Problem
with a State Machine ......................... 55
5.3 Costatements ............................................ 56
5.3.1 Solving the Real-Time Problem
with Costatements ............................. 56
5.3.2 Costatement Syntax ..................... 57
5.3.3 Control Statements....................... 57
5.4 Advanced Costatement Topics ................. 59
5.4.1 The CoData Structure .................. 59
5.4.2 CoData Fields .............................. 60
5.4.3 Pointer to CoData Structure......... 61
5.4.4 Functions for Use With Named
Costatements ..................................... 61
5.4.5 Firsttime Functions ...................... 62
5.4.6 Shared Global Variables............... 62
5.5 Cofunctions .............................................. 62
5.5.1 Cofunction Syntax ....................... 62
5.5.2 Calling Restrictions...................... 63
5.5.3 CoData Structure.......................... 64
5.5.4 Firsttime Functions ...................... 64
5.5.5 Types of Cofunctions ................... 64
5.5.6 Types of Cofunction Calls ........... 66
5.5.7 Special Code Blocks .................... 67
5.5.8 Solving the Real-Time Problem
with Cofunctions ............................... 68
4 digi.com Table of Contents
5.6 Patterns of Cooperative Multitasking .......68
5.7 Timing Considerations ..............................69
5.7.1 waitfor Accuracy Limits...............69
5.8 Overview of Preemptive Multitasking ......70
5.9 Slice Statements ........................................70
5.9.1 Slice Syntax..................................70
5.9.2 Usage ............................................70
5.9.3 Restrictions ...................................71
5.9.4 Slice Data Structure ......................71
5.9.5 Slice Internals ...............................71
5.10 µC/OS-II...................................................74
5.10.1 Changes to µC/OS-II ..................74
5.10.2 Tasking Aware Interrupt Service
Routines (TA-ISR) .............................76
5.10.3 Library Reentrancy.....................82
5.10.4 How to Get a µC/OS-II Application
Running..............................................83
5.10.5 Compatibility with TCP/IP.........88
5.10.6 Debugging Tips ..........................89
5.11 Summary ..................................................89
6. Debugging with Dynamic C............................91
6.1 Debugging Features Prior to Dynamic C 991
6.2 Debugging Features Introduced in Dynamic
C 9 .............................................................92
6.3 Debugging Tools .......................................93
6.3.1 printf()...........................................93
6.3.2 Software Breakpoints ...................94
6.3.3 Single Stepping............................ 96
6.3.4 Watch Expressions........................97
6.3.5 Evaluate Expressions....................98
6.3.6 Memory Dump .............................99
6.3.7 MAP File ....................................100
6.3.8 Execution Trace..........................102
6.3.9 Symbolic Stack Trace.................103
6.3.10 Assert Macro ........................... 104
6.3.11 Miscellaneous Debugging Tools.....
104
6.4 Where to Look for Debugger Features ...107
6.4.1 Run and Inspect Menus ..............108
6.4.2 Options Menu .............................108
6.4.3 Window Menu ............................108
6.5 Debug Strategies .....................................109
6.5.1 Good Programming Practices.....109
6.5.2 Finding the Bug ..........................110
6.6 Reference to Other Debugging Information .
112
7. The Virtual Driver...........................................113
7.1 Default Operation....................................113
7.2 Calling _GLOBAL_INIT() .....................113
7.3 Global Timer Variables ...........................114
7.3.1 Example: Timing Loop...............114
7.3.2 Example: Delay Loop.................115
7.4 Watchdog Timers ....................................116
7.4.1 Hardware Watchdog ...................116
7.4.2 Virtual Watchdogs ...................... 116
7.5 Preemptive Multitasking Drivers............ 117
8. Run-Time Errors ............................................. 119
8.1 Run-Time Error Handling....................... 119
8.1.1 Error Code Ranges ..................... 119
8.1.2 Fatal Error Codes .......................120
8.2 User-Defined Error Handler ...................121
8.2.1 Replacing the Default Handler...121
8.3 Run-Time Error Logging ........................122
8.3.1 Error Log Buffer.........................122
8.3.2 Initialization and Defaults.......... 123
8.3.3 Configuration Macros ................ 123
8.3.4 Error Logging Functions ............124
8.3.5 Examples of Error Log Use........124
9. Memory Management....................................125
9.1 Memory Map ..........................................125
9.1.1 Memory Mapping Control .........126
9.1.2 Macro to Use Second Flash for Code
126
9.2 Extended Memory Functions..................126
9.3 Code Placement in Memory ...................126
9.4 Dynamic Memory Allocation .................127
10. File Systems.....................................................129
10.1 FS2 .........................................................129
10.1.1 General Usage ..........................129
10.1.2 Application Requirements........131
10.1.3 File System API Functions.......134
10.1.4 Setting up and Partitioning the File
System .............................................135
10.1.5 File Identifiers .......................... 137
10.1.6 Skeleton Program Using FS2 ... 139
10.2 FAT File System.....................................140
10.2.1 Overview of FAT Documentation ..
141
10.2.2 Running Your First FAT Sample
Program ...........................................141
10.2.3 More Sample Programs............148
10.2.4 FAT Operations ........................154
10.2.5 More FAT Information .............164
11. Using Assembly Language............................171
11.1 Mixing Assembly and C.........................171
11.1.1 Embedded Assembly Syntax.... 171
11.1.2 Embedded C Syntax .................172
11.1.3 Setting Breakpoints in Assembly ...
172
11.2 Assembler and Preprocessor ..................173
11.2.1 Comments.................................173
11.2.2 Defining Constants ...................173
11.2.3 Multiline Macros ...................... 175
11.2.4 Labels .......................................175
11.2.5 Special Symbols .......................175
11.2.6 C Variables ...............................176
Dynamic C Users Manual digi.com 5
11.3 Stand-Alone Assembly Code ................. 177
11.3.1 Stand-Alone Assembly Code in
Extended Memory ........................... 177
11.3.2 Example of Stand-Alone Assembly
Code................................................. 178
11.4 Embedded Assembly Code .................... 178
11.4.1 The Stack Frame....................... 178
11.4.2 Embedded Assembly Example 180
11.4.3 The Disassembled Code Window ..
181
11.4.4 Local Variable Access .............. 182
11.5 C Calling Assembly ............................... 183
11.5.1 Passing Parameters................... 183
11.5.2 Location of Return Results....... 183
11.5.3 Returning a Structure ............... 183
11.6 Assembly Calling C ............................... 185
11.7 Interrupt Routines in Assembly ............. 186
11.7.1 Steps Followed by an ISR ........ 186
11.7.2 Modifying Interrupt Vectors..... 187
11.8 Common Problems................................. 192
12. Keywords......................................................... 193
abandon ............................................... 193
abort .................................................... 193
align..................................................... 194
always_on............................................ 194
anymem............................................... 194
asm ...................................................... 195
auto...................................................... 195
bbram .................................................. 195
break.................................................... 196
c........................................................... 196
case...................................................... 196
char...................................................... 197
cofunc.................................................. 197
const .................................................... 198
continue............................................... 199
costate.................................................. 199
debug................................................... 199
default.................................................. 200
do......................................................... 200
else ...................................................... 200
enum.................................................... 201
extern................................................... 201
firsttime ............................................... 202
float ..................................................... 202
for ........................................................ 203
goto...................................................... 203
if .......................................................... 204
init_on ................................................. 204
int ........................................................ 205
interrupt............................................... 205
interrupt_vector................................... 206
__lcall__.............................................. 208
long...................................................... 208
main..................................................... 208
nodebug............................................... 209
norst..................................................... 209
nouseix ................................................ 209
NULL .................................................. 209
protected.............................................. 210
register ................................................ 210
return................................................... 211
root ...................................................... 211
scofunc ................................................ 211
segchain .............................................. 212
shared.................................................. 212
short .................................................... 213
size ...................................................... 213
sizeof................................................... 213
speed ................................................... 213
static.................................................... 214
struct.................................................... 214
switch.................................................. 215
typedef ................................................ 215
union ................................................... 216
unsigned.............................................. 216
useix .................................................... 216
void ..................................................... 217
volatile ................................................ 217
waitfor................................................. 217
waitfordone
(wfd) ............................................ 218
while.................................................... 218
xdata.................................................... 219
xmem .................................................. 220
xstring ................................................. 220
yield .................................................... 221
12.1 Compiler Directives............................... 222
#asm .................................................... 222
#class................................................... 222
#debug
#nodebug ..................................... 223
#define ................................................ 223
#endasm .............................................. 223
#fatal ................................................... 223
#GLOBAL_INIT ................................ 224
#error................................................... 224
#funcchain........................................... 224
#if
#elif
#else
#endif ........................................... 225
#ifdef................................................... 225
#ifndef................................................. 226
#interleave
#nointerleave ............................... 226
#makechain ......................................... 226
#memmap............................................ 227
#pragma .............................................. 227
#precompile ........................................ 228
#undef ................................................. 228
#use ..................................................... 228
#useix
#nouseix....................................... 229
#warns................................................. 229
#warnt ................................................. 229
#ximport.............................................. 229
#zimport .............................................. 230
13. Operators ......................................................... 231
13.1 Arithmetic Operators ............................. 232
+ .......................................................... 232
.......................................................... 232
* .......................................................... 233
6 digi.com Table of Contents
/............................................................233
++.........................................................234
–– .........................................................234
%..........................................................234
13.2 Assignment Operators ............................235
=...........................................................235
+=.........................................................235
-= .........................................................235
*=.........................................................235
/=..........................................................235
%= .......................................................235
<<= ......................................................235
>>= ......................................................236
&=........................................................236
^=.........................................................236
|= ..........................................................236
13.3 Bitwise Operators...................................236
<<.........................................................236
>>.........................................................236
& ..........................................................237
^ ...........................................................237
| ............................................................237
~...........................................................237
13.4 Relational Operators...............................238
<...........................................................238
<=.........................................................238
>...........................................................238
>=.........................................................238
13.5 Equality Operators..................................239
==.........................................................239
!= .........................................................239
13.6 Logical Operators...................................239
&&.......................................................239
|| ...........................................................239
!............................................................240
13.7 Postfix Expressions ................................240
( ) .........................................................240
[ ] .........................................................240
. (dot) ...................................................240
-> .........................................................241
13.8 Reference/Dereference Operators ..........241
& ..........................................................241
* ...........................................................241
13.9 Conditional Operators ............................242
? : .........................................................242
13.10 Other Operators ....................................243
(type)....................................................243
sizeof....................................................243
, ............................................................244
14. Graphical User Interface ................................245
14.1 Editing ....................................................245
14.2 Menus .....................................................246
14.2.1 Using Keyboard Shortcuts........246
14.2.2 File Menu..................................247
14.2.3 Edit Menu.................................249
14.2.4 Compile Menu..........................253
14.2.5 Run Menu.................................255
14.2.6 Inspect Menu...........................257
14.2.7 Options Menu...........................261
Environment Options ................... 261
Editor Tab ................................261
Gutter & Margin Tab ...............264
Display Tab..............................266
Syntax Colors Tab....................267
Code Templates Tab.................268
Debug Windows Tab................269
Print/Alerts Tab........................276
Project Options.............................277
Communications Tab ...............277
Compiler Tab ........................... 279
Debugger Tab...........................285
Defines Tab..............................288
Targetless Tab .......................... 290
14.2.8 Window Menu......................... 293
14.2.9 Help Menu................................299
15. Command Line Interface..............................303
15.1 Default States .........................................303
15.2 User Input...............................................303
15.3 Saving Output to a File ..........................304
15.4 Command Line Switches .......................304
15.4.1 Switches Without Parameters...304
15.4.2 Switches Requiring a Parameter312
15.5 Examples................................................320
15.6 Command Line RFU.............................. 321
16. Project Files .....................................................325
16.1 Project File Names.................................325
16.1.3 Active Project...........................325
16.2 Updating a Project File ..........................326
16.3 Menu Selections..................................... 326
16.4 Command Line Usage............................327
17. Hints and Tips .................................................329
17.1 A User-Defined BIOS ............................329
17.2 Efficiency ............................................... 330
17.2.1 Nodebug Keyword ...................330
17.2.2 In-line I/O.................................331
17.3 Run-time Storage of Data ......................331
17.3.1 User Block................................ 332
17.3.2 Flash File System .....................332
17.3.3 WriteFlash2 ..............................332
17.3.4 Battery-Backed RAM...............332
17.4 Root Memory Reduction Tips................333
17.4.1 Increasing Root Code Space ....333
17.4.2 Increasing Root Data Space .....335
Appendix A: Macros and Global Variables .... 337
Macros Defined by the Compiler .............. 337
Macros Defined in the BIOS or Configuration
Libraries ................................................. 340
Dynamic C Users Manual digi.com 7
Global Variables ........................................ 341
Exception Types ........................................ 342
Rabbit Registers ........................................ 342
Appendix B: Map File Generation .................. 343
Grammar.................................................... 343
Appendix C: Security Software & Utility Programs
345
Rabbit Embedded Security Pack ............... 345
AES .................................................. 345
SSL .................................................. 345
Dynamic C Utilities................................... 346
Library File Encryption ...................... 346
File Compression Utility .................... 347
Font and Bitmap Converter Utility ....349
Rabbit Field Utility ............................ 349
Appendix D: Additional Documentation......... 355
Index ................................................................ 357
8 digi.com Table of Contents
Dynamic C Users Manual digi.com 9
1. INSTALLING DYNAMIC C
Insert the installation disk or CD in the appropriate disk drive on your PC. The installation should begin
automatically. If it doesn’t, issue the Windows “Run...” command and type the following command
‹disk›:\SETUP
The installation program will begin and guide you through the installation process.
1.1 Requirements
Dynamic C requires an IBM-compatible PC running Windows 2000 or later with at least one free COM or
USB port.
Please note that Windows Vista is supported by Dynamic C out of the box if there is only one processor in
the host PC or laptop. With multiple processors (a.k.a., dual cores) present in the host system, you must
check Windows “Processor Affinity” setting in order to ensure Vista compatibility with Dynamic C. Tech-
nical note TN257 “Running Dynamic C with Windows Vista” has instructions for modifying the “Proces-
sor Affinity” setting. This technical note is available on the Digi website:
www.digi.com/support/
Starting with Dynamic C 9.60, the “Processor Affinity” setting is set automatically.
1.2 Assumptions
It is assumed that the reader has a working knowledge of:
The basics of operating a software program and editing files under Windows on a PC.
Programming in a high-level language.
Assembly language and architecture for controllers.
Refer to one or both of the following texts for a full treatment of C:
The C Programming Language by Kernighan and Ritchie (published by Prentice-Hall).
C: A Reference Manual by Harbison and Steel (published by Prentice-Hall).
10 digi.com Installing Dynamic C
Dynamic C Users Manual digi.com 11
2. INTRODUCTION TO DYNAMIC C
Dynamic C is an integrated development system for writing embedded software. It is designed for use with
Rabbit controllers and other controllers based on the Rabbit microprocessor.
2.1 The Nature of Dynamic C
Dynamic C integrates the following development functions:
Editing
Compiling
Linking
Loading
Debugging
into one program. In fact, compiling, linking and loading are one function. Dynamic C has an easy-to-use,
built-in, full-featured text editor. Dynamic C programs can be executed and debugged interactively at the
source-code or machine-code level. Pull-down menus and keyboard shortcuts for most commands make
Dynamic C easy to use.
Dynamic C also supports assembly language programming. It is not necessary to leave C or the develop-
ment system to write assembly language code. C and assembly language may be mixed together.
Debugging under Dynamic C includes the ability to use printf commands, watch expressions and
breakpoints. Watch expressions can be used to compute C expressions involving the target’s program vari-
ables or functions. Watch expressions can be evaluated while stopped at a breakpoint or while the target is
running its program. Dynamic C 9 introduces advanced debugging features such as execution and stack
tracing. Execution tracing can be used to follow the execution of debuggable statements, including such
information as function/file name, source code line and column numbers, action performed, time stamp of
action performed and register contents. Stack tracing shows function call sequences and parameter values.
Dynamic C provides extensions to the C language (such as shared and protected variables, costatements
and cofunctions) that support real-world embedded system development. Dynamic C supports cooperative
and preemptive multitasking.
Dynamic C comes with many function libraries, all in source code. These libraries support real-time pro-
gramming, machine level I/O, and provide standard string and math functions.
2.1.1 Speed
Dynamic C compiles directly to memory. Functions and libraries are compiled and linked and downloaded
on-the-fly. On a fast PC, Dynamic C might load 30,000 bytes of code in five seconds at a baud rate of
115,200 bps.
12 digi.com Introduction to Dynamic C
2.2 Dynamic C Enhancements and Differences
Dynamic C differs from a traditional C programming system running on a PC or under UNIX. The reason?
To better help customers write the most reliable embedded control software possible. It is not possible to
use standard C in an embedded environment without making adaptations. Standard C makes many
assumptions that do not apply to embedded systems. For example, standard C implicitly assumes that an
operating system is present and that a program starts with a clean slate, whereas embedded systems may
have battery-backed memory and may retain data through power cycles. Rabbit has extended the C lan-
guage in a number of areas.
2.2.1 Dynamic C Enhancements
Many enhancements have been added to Dynamic C. Some of these are listed below.
Function Chaining, a concept unique to Dynamic C, allows special segments of code to be embedded
within one or more functions. When a named function chain executes, all the segments belonging to
that chain execute. Function chains allow software to perform initialization, data recovery, or other
kinds of tasks on request.
Costatements allow cooperative, parallel processes to be simulated in a single program.
Cofunctions allow cooperative processes to be simulated in a single program.
Slice Statements allow preemptive processes in a single program.
Dynamic C supports embedded assembly code and stand-alone assembly code.
Dynamic C has keywords that help protect data shared between different contexts (shared) or stored in
battery-backed memory (protected).
Dynamic C has a set of features that allow the programmer to make the fullest use of xmem (extended
memory). The compiler supports a 1 MB physical address space.
Normally, Dynamic C takes care of memory management, but there are instances where the program-
mer will want to take control of it. Dynamic C has keywords and directives to help put code in the
proper place, such as: root, xmem, and #memmap.
See Chapter 9 for further details on memory management.
Dynamic C Users Manual digi.com 13
2.2.2 Dynamic C Differences
The main differences in Dynamic C are summarized in the list below and discussed in detail in Chapter 4.
“Language” and Chapter 12. “Keywords”.
If a variable is explicitly initialized in a declaration (e.g., int x = 0;), it is stored in flash memory
(EEPROM) and cannot be changed by an assignment statement. Such a declaration will generate a
warning that may be suppressed using the const keyword:
const int x = 0
To initialize static variables in Static RAM (SRAM) use #GLOBAL_INIT sections. Note that other C
compilers will automatically initialize all static variables to zero that are not explicitly initialized before
entering the main function. Dynamic C programs do not do this because in an embedded system you
may wish to preserve the data in battery-backed RAM on reset
The numerous include files found in typical C programs are not used because Dynamic C has a library
system that automatically provides function prototypes and similar header information to the compiler
before the users program is compiled. This is done via the #use directive. This is an important topic
for users who are writing their own libraries. Those users should refer to Section 4.23, “Modules” for
more information.
When declaring pointers to functions, arguments should not be used in the declaration. Arguments may
be used when calling functions indirectly via pointer, but the compiler will not check the argument list
in the call for correctness. See Section 4.16 for more information
Bit fields are not supported.
Separate compilation of different parts of the program is not supported or needed.
14 digi.com Introduction to Dynamic C
2.3 Rabbit and Z180 Comparison
A major difference in the way Dynamic C interacts with a Rabbit-based board compared to a Z180 or
386EX board is that Dynamic C expects no BIOS kernel to be present on the target when it starts up.
Dynamic C stores the BIOS kernel as a C source file. Dynamic C compiles and loads it to the Rabbit target
when it starts. This is accomplished using the Rabbit CPU’s bootstrap mode and a special programming
cable provided in all Rabbit product development kits. This method has numerous advantages.
A socketed flash is no longer needed. BIOS updates can be made without a flash-EPROM burner since
Dynamic C can communicate with a target that has a blank flash EPROM. Blank flash EPROM can be
surface-mounted onto boards, reducing manufacturing costs for both Rabbit and other board develop-
ers. BIOS updates can then be made available on the Web.
Advanced users can see and modify the BIOS kernel directly.
Board developers can design Dynamic C compatible boards around the Rabbit CPU by simply follow-
ing a few simple design guidelines and using a “skeleton” BIOS provided by Rabbit.
A major feature is the ability to program and debug over the Internet or local Ethernet. This requires
either the use of a RabbitLink board, available alone or as an option with Rabbit-based development
kits, or the use of RabbitSys.
Dynamic C Users Manual digi.com 15
3. QUICK TUTORIAL
Sample programs are provided in the Dynamic C Samples folder, which is in the root directory where
Dynamic C was installed. The Samples folder contains many subfolders, as shown in Figure 3.1. Sample
programs are provided in source code format. You can open the source code file in Dynamic C and read
the comment block at the top of the sample program for a description of its purpose and other details.
Comments are also provided throughout the source code. This documentation, provided by the software
engineers, is a rich source of information.
Figure 3.1 Screenshot of Samples Folder
The subfolders contain sample programs that illustrate the use of the various Dynamic C libraries. For
example, the subfolders “Cofunc” and “Costate” have sample programs illustrating the use of
COFUNC.LIB and COSTATE.LIB, libraries that support cooperative multitasking using Dynamic C lan-
guage extensions. Besides its subfolders, the Samples folder also contains some sample programs to dem-
onstrate various aspects of Dynamic C. For example, the sample program Pong.c demonstrates output
to the Stdio window.
In the rest of this chapter we examine four sample programs in some detail.
16 digi.com Quick Tutorial
3.1 Run DEMO1.C
This sample program will be used to illustrate some of the functions of Dynamic C. Open the file
Samples/DEMO1.C using the File menu or the keyboard shortcut <Ctrl+O>. The program will appear
in a window, as shown in Figure 3.2 (minus some comments). Use the
mouse to place the cursor on the
function name
printf
in the program and press
<Ctrl+H>
.
This brings up a Function Description window
for printf(). You can do this with all functions in the Dynamic C libraries, including libraries you
write yourself.
Figure 3.2 Sample Program DEMO1.C
To run DEMO1.C compile it using the Compile menu, and then run it by selecting “Run” in the
Run menu. (The keyboard shortcut <F9> will compile and run the program. You may also use the
green triangle toolbar button as a substitute for <F9>.)
The value of the counter should be printed repeatedly to the Stdio window if everything went well. If this
doesn’t work, review the following points:
The target should be ready, indicated by the message “BIOS successfully compiled...” If you did not
receive this message or you get a communication error, recompile the BIOS by pressing <Ctrl+Y> or
select “Reset Target / Compile BIOS” from the Compile menu.
A message reports “No Rabbit Processor Detected” in cases where the wall transformer is not con-
nected or not plugged in.
The programming cable must be connected to the controller. (The colored wire on the programming
cable is closest to pin 1 on the programming header on the controller). The other end of the program-
ming cable must be connected to the PC serial port. The COM port specified in the Communications
Dynamic C Users Manual digi.com 17
dialog box must be the same as the one the programming cable is connected to. (The Communications
dialog box is accessed via the Communications tab of the Options | Project Options menu.)
To check if you have the correct serial port, press <Ctrl+Y>. If the “BIOS successfully compiled …”
message does not display, choose a different serial port in the Communications dialog box until you
find the serial port you are plugged into. Dont change anything in this menu except the COM number.
The baud rate should be 115,200 bps and the stop bits should be 1.
3.1.1 Single Stepping
To experiment with single stepping, we will first compile DEMO1.C to the target without run-
ning it. This can be done by clicking the compile button on the task bar. This is the same as press-
ing F5. Both of this actions will compile according to the setting of “Default Compile Mode.”
(See “Default Compile Mode” in Chapter 14, for how to set this parameter.) Alternatively you may select
Compile | Compile to Target from the main menu.
After the program compiles a highlighted character (green) will appear at the first executable
statement of the program. Press the <F8> key to single step (or use the toolbar button). Each time
the <F8> key is pressed, the cursor will advance one statement. When you get to the statement:
for(j=0, j< ... , it becomes impractical to single step further because you would have to press
<F8> thousands of times. We will use this statement to illustrate watch expressions.
3.1.2 Watch Expression
Watch expressions may only be added, deleted or updated in run mode. To add a watch expres-
sion click on the toolbar button pictured here, or press <Ctrl+W> or choose “Add Watch” from
the Inspect menu. The Add Watch Expression popup box will appear. Type the lower case letter
“j” and click on either “Add” or “OK.” The former keeps the popup box open, the latter closes it. Either
way the Watches window appears. This is where information on watch expressions will be displayed. Now
continue single stepping. Each time you do, the watch expression (j) will be evaluated and printed in the
Watches window. Note how the value of “j” advances when the statement j++ is executed.
3.1.3 Breakpoint
Move the cursor to the start of the statement:
for (j=0; j<20000; j++);
To set a breakpoint on this statement, press <F2> or select “Toggle Breakpoint” from the Run menu. A red
highlight appears on the first character of the statement. To get the program running at full speed, press
<F9>. The program will advance until it hits the breakpoint. The breakpoint will start flashing both red and
green colors.
To remove the breakpoint, press <F2> or select “Toggle Breakpoint” on the Run menu. To continue pro-
gram execution, press <F9>. You will see the value of “i” displayed in the Stdio window repeatedly until
program execution is halted.
You can set breakpoints while the program is running by positioning the cursor to a statement and using
the <F2> key. If the execution thread hits the breakpoint, a breakpoint will take place. You can toggle the
breakpoint with the <F2> key and continue execution with the <F9> key.
18 digi.com Quick Tutorial
Starting with Dynamic C 9, you can also set breakpoints while in edit mode. Breakpoint information is not
only retained when going back and forth from edit mode to debug mode, it is stored when a file is closed
and restored when the file is re-opened.
3.1.4 Editing the Program
Press <F4>to put Dynamic C into edit mode. Use the “Save as” choice on the File menu to save the file
with a new name so as not to change the original demo program. Save the file as MYTEST.C. Now change
the number 20000 in the for statement to 10000. Then use the <F9> key to recompile and run the pro-
gram. The counter displays twice as quickly as before because you reduced the value in the delay loop.
3.2 Run DEMO2.C
Go back to edit mode and open the program DEMO2.C. This program is the same as the first program,
except that a variable k has been added along with a statement to increment “k” by the value of “i” each
time around the endless loop. Compile and run DEMO2.C.
3.2.1 Watching Variables Dynamically
Press <Ctrl+W> to open the “Add Watch Expression” popup box.
Type “k” in the text entry box, then
click “OK” (or “Add”) to add the
expression “k” to the top of the list of
watch expressions. Now press
<Ctrl+U>, the keyboard shortcut for
updating the watch window. Each
time you press
<Ctrl+U>, you will see
the current value of k.
Add another expression to the watch window:
k*5
Then press <Ctrl+U> several times to observe the watch expressions “k” and “k*5.”
Dynamic C Users Manual digi.com 19
3.3 Run DEMO3.C
The example below, sample program DEMO3.C, uses costatements. A costatement is a way to perform a
sequence of operations that involve pauses or waits for some external event to take place.
3.3.1 Cooperative Multitasking
Cooperative multitasking is a way to perform several different tasks at virtually the same time. An exam-
ple would be to step a machine through a sequence of tasks and at the same time carry on a dialog with the
operator via a keyboard interface. Each separate task voluntarily surrenders its compute time when it does
not need to perform any more immediate activity. In preemptive multitasking control is forcibly removed
from the task via an interrupt.
Dynamic C has language extensions to support both types of multitasking. For cooperative multitasking
the language extensions are costatements and cofunctions. Preemptive multitasking is accomplished with
slicing or by using the µC/OS-II real-time kernel.
Advantages of Cooperative Multitasking
Unlike preemptive multitasking, in cooperative multitasking variables can be shared between different
tasks without taking elaborate precautions. Cooperative multitasking also takes advantage of the natural
delays that occur in most tasks to more efficiently use the available processor time.
The DEMO3.C sample program has two independent tasks. The first task prints out a message to Stdio
once per second. The second task watches to see if the keyboard has been pressed and prints the entered
key.
The numbers in the left margin are reference indicators and not part of the code. Load and run the pro-
gram. The elapsed time is printed to the Stdio window once per second. Push several keys and note how
they are reported.
main() {
int secs; // seconds counter
secs = 0; // initialize counter
(1) while (1) { // endless loop
// First task will print the seconds elapsed.
(2) costate {
secs++; // increment counter
(3) waitfor( DelayMs(1000) ); // wait one second
printf("%d seconds\n", secs); // print elapsed seconds
(4) }
// Second task will check if any keys have been pressed.
costate {
(5) if ( !kbhit() ) abort; // key been pressed?
printf(" key pressed = %c\n", getchar() );
}
(6) } // end of while loop
} // end of main
20 digi.com Quick Tutorial
The elapsed time message is printed by the costatement starting at the line marked (2). Costatements need
to be executed regularly, often at least every 25 ms. To accomplish this, the costatements are enclosed in a
while loop. The while loop starts at (1) and ends at (6). The statement at (3) waits for a time delay, in
this case 1000 ms (one second). The costatement executes each pass through the while loop. When a
waitfor condition is encountered the first time, the current value of MS_TIMER is saved and then on
each subsequent pass the saved value is compared to the current value. If a waitfor condition is not
encountered, then a jump is made to the end of the costatement (4), and on the next pass of the loop, when
the execution thread reaches the beginning of the costatement, execution passes directly to the waitfor
statement. Once 1000 ms has passed, the statement after the waitfor is executed. A costatement can
wait for a long period of time, but not use a lot of execution time. Each costatement is a little program with
its own statement pointer that advances in response to conditions. On each pass through the while loop
as few as one statement in the costatement executes, starting at the current position of the costatement’s
statement pointer. Consult Chapter 5 for more details.
The second costatement in the program checks to see if an alpha-numeric key has been pressed and, if one
has, prints out that key. The abort statement is illustrated at (5). If the abort statement is executed, the
internal statement pointer is set back to the first statement in the costatement, and a jump is made to the
closing brace of the costatement.
Observe the value of secs while the program is running.To illustrate the use of snooping, use the watch
window to observe secs while the program is running. Add the variable secs to the list of watch expres-
sions, then press <Ctrl+U> repeatedly to observe as secs increases.
3.4 Run DEMO4.C
The sample program DEMO4.C uses execution tracing. This is one of the advanced debugging features
introduced in Dynamic C 9. Tracing records program state information based on options you choose in the
Debugger tab of the Project Options dialog. The information captured from the target by Dynamic C’s
tracing feature is displayed in the Trace window, available from the Window menu. To make the target
send trace information, you must turn on tracing either from the
INSPECT menu or from within your pro-
gram using one of the macros described here.
To use this sample program, first go to the
Debugger tab of the Project Options dialog,
select Enable Tracing, and choose Full for
the Trace Level. Click OK to save and close
the dialog, then compile and run DEMO4.C.
When the program finishes, the Trace win-
dow will open and you can examine its
entries. The Trace window can be opened
anytime after the program is compiled, but execution speed is slightly affected if the window is open while
the program is running.
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