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ucosii的源代码希望能给予学习嵌入式系统的朋友一定的帮助

Test and example program for uC/OS-II and avr-gcc 3.x
-----------------------------------------------------

If you have version 2.52 of uC/OS-II (the one which comes with the book)
or any version other than 2.70, see notes at the end of this document!

This is a test and example program to be used with uC/OS-II version
2.70, Atmel's ATmega 128 and avr-gcc version 3.x. This example is a
modification of the example #1 in Labrosse's book. The modifications
to AVR were originally made by Ole Saether for the IAR compiler and
ported to gcc version 2.95 by Jesper Hansen. I have made a number of
changes to the program including, but not limited to:

- ISR programming is done using a macro UCOSISR(), which is
defined in avr_isr.h (by me). avr_isr.h is included in the port.

- ISR code is changed a bit to conform to the requirements of uC/OS-II
as documented by Labrosse's book. The general structure of an ISR
using my macros is

UCOSISR(validsignalname)
{
  PushRS();
  OSIntEnter();
  if (OSIntNesting == 1)
    OSTCBCur->OSTCBStkPtr = (OS_STK *)SP;

  /* Do what you want the ISR to do */

  sei();
  OSIntExit();
  PopRS();
}

UCOSISR() is used instead of macros SIGNAL() and INTERRUPT() from
avr-libc. DO NOT use SIGNAL() or INTERRUPT() with uC/OS-II, since they
save only the used registers on the stack, whereas uC/OS-II requires
that all the registers are saved. If a task switch is needed after or
during the ISR, the context of the current task will be trashed the
next time it is run. You can use SIGNAL(), since it does not enable
interrupts during the ISR, but then you MUST NOT use any of the
services provided by uC/OS-II. Thus, if you must e.g. signal a task
using a semaphore, UCOSISR() is the only way to do it.

- PushRS() and PopRS() are also macros provided by avr_isr.h. The push
and pop all the registers to or from the stack.

- sei() is a macro provided by avr-libc (by including
avr/interrupt.h). SP (stack pointer) is also provided by avr-libc in
avr/io.h (or the correct io*.h file included by avr/io.h)

- I use UART Data Register Empty Interrupt instead of UART Transmit
Complete Interrupt. The main part of the ISR is thus changed a bit and
PutChar also.

- I/O-ports are accessed using the now preferred syntax, e.g.

	TCCR0=0;                 /* before: outb(TCCR0,0) or outp(0,TCCR0) */
	UCSR0B &= ~_BV(UDRIE0);  /* before: outb(UCSR0B,inb(UCSR0B) &~ (1<<UDRIE0)) */

  The syntax is now the same as with other compilers for AVR.

- I changed the UART trasmit buffer pointers and counter to 16 bit
variables in case you want the transmit buffer's length to be more
than 256 bytes.

- I reduced the number of tasks to 8 and the size of the task stacks
to 128. This way the program fits into the internal SRAM of ATMega128.

- makefile is now based on the sample makefile distributed with
Winavr. I have made changes so that uC/OS-II and port sources can
reside anywhere in your file system and you do not need to have write
access to these directories. All the created files (object files, hex
file etc.)  are saved on the current directory (where your application
sources are). You can therefore copy this example from to your home
directory and compile it there.

- makefile includes the changes needed to create a coff file from the
elf file. In order to use this, you need to have avr-binutils pathced
with J鰎g Wunsch's patch. The patch allows avrstudio to simulate your
code. Be warned though, that due to the limitation of the coff file
format, include files are problematic. So, in order to be able to step
into uC/OS-II code, you need to change the main uC/OS-II sources so
that it is not based on including all the sources into ucos_ii.c. I
have not done this, but it should be possible. You should be able to
simulate your application code without these changes.

- you can compile your code with a unix version of avr-gcc, too. See
the readme.txt file of the port in the doc directory for help on how
to do this. In fact, in mostly use the linux version of avr-gcc and
program the device with avrdude. Works perfectly.

Notes to get the example program to work with uC/OS-II v2.52
------------------------------------------------------------

includes.h
----------

- uncomment the lines for including os_cpu.h and os_cfg.h (these are
included in ucos_ii.h from 2.70 on

makefile
--------

- change the directory names UCOSDIR and PORTDIR to reflect the right directories. 
- remove os_dbg.c from the list of uC/OS-II source files (UCOSSRC)

os_cfg.h
--------

- some new definitions are added for v2.70 but there is no need to delete them,
therefore os_cfg.h can be left unchanged.

I have also provided the modified files as includes.h.252 and makefile.252. You 
can copy them as includes.h and makefile, but you should anyway check the makefile.



Feel free to contact me in case of problems both with this program or
the port.

Julius Luukko ([e-mail])
21th of July, 2003.