embOS for National Semiconductor CR16C was developed for and with IAR's compiler and supports nearly all memory models offered by this compiler. It comes with an easy to use start project for IAR's embedded workbench. Software development with WinIdea debugger is supported.

Resources and performance data

Memory usage
Kernel size (ROM)	< 1800 bytes
Kernel RAM usage	40 bytes
RAM usage per task control block	28 bytes
RAM usage per resource semaphore	14 bytes
RAM usage per counting semaphore	6 bytes
RAM usage per mailbox	16 bytes
RAM usage per software timer	14 bytes
RAM usage event	0 bytes
Min. stack-size per task (RAM)	28 bytes
Timing
Context switch time	tbd
Interrupt latency time	tbd
Kernel CPU usage/TICK	less than .4% of total calculation time at 1000 Interrupts/second (1ms TICK)
Basic time unit (TICK)	typ. 1 ms, min. 20 µs (50 kHz interrupt frequency)
Features
Max. no. of tasks	Unlimited (by available RAM only)
Max. no. of mailboxes	unlimited (by available RAM only)
Max. no. of semaphores (resource/binary/counting)	unlimited (by available RAM only)
Max. no. of software timers	unlimited (by available RAM only)
Max. no. of priorities	255
Stack size idle task (RAM)	0 (no memory needed)
Nested interrupts	permitted
Task switches from within ISR	possible

Absolute timings given above were measured with embOS release build

embOSView offers system analysis during runtime

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Additional information

IAR Web site for additional compiler info / support

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Release notes

1. Tool chain used for build
2. New features
3. Improvements
4. Program corrections
5. Known problems/limitations
6. Release history
7. Miscellaneous

Tool chain used for build

The following tools have been used:

Compiler:  IAR ICCCR16C  V2.11a
Assembler: IAR ACR16C    V2.11a
Librarian: IAR XAR       V1.03L
Workbench: IAR IARIDE    V4.6B

New features

Version 3.32m

1. OS_TimerEx, Extended timer implemented
   Extended timers are software timers which call a user defined callback function when the timer expires.
   In comparison to normal embOS timers, a parameter is passed to the timer callback function.
   The parameter value is initialized during timer creation.

Version 3.32l

OS_EnterIntStack() and OS_LeaveIntStack are implemented to safe space on task stack.

Version 3.32j

First version. None.

Improvements

Version 3.32o

1. Automatic call of OS_INIT_SYS_LOCKS() removed.
   During initialization of embOS, OS_INIT_SYS_LOCK() is not called automatically.
   As most of the applications do not need thread safe system libraries, an automatic activation of syslocks causes unwanted overhead.
   If supported and required, the user may call OS_INIT_SYS_LOCKS() from his own application after normal initialization of embOS.

Program corrections

Version 3.32o

1. OS_Unuse() corrected
   OS_Unuse() must not be called from a task that does not claim the resource semaphore.
   According to the documentation, the debug build of embOS should generate a call to OS_Error() if this fault happens.
   All previous versions of embOS did not call OS_Error(). Now, OS_Error() will be called in that situation with error code 156: OS_ERR_RESOURCE_OWNER().
2. Enter-/LeaveIntStack corrected
   A word access to a byte variable caused errors

Version 3.32l1

1. Stack switch corrected
   Interrupts must be disabled while counter for default stack is changed and stackpointer is set to default stack.

Version 3.32l

1. OS_EVENT_Delete() corrected
   OS_EVENT_Delete() did not work correctly. OS_LeaveRegion() was called inside the function without calling OS_EnterRegion() bfore.
   In debug builds of embOS, the error handler OS_Error() was called with error 151 (OS_ERR_LEAVEREGION_BEFORE_ENTERREGION).
   In release builds the system was blocked because the underflow of region count inhibts all further task switches, or system crashes, because incrementing the region count the next time allows task switches instead of blocking them. The problem existed in all previous versions and is fixed with version 3.32l.
2. Round-robin task switching corrected.
   Round robin task switching did not work correctly in previous version. A task which was blocked for some reason could be activated. The system crashed during task switch.
   The problem existed since version 3.32j and is fixed with version 3.32l.

Version 3.32k

1. Handler function _OS_OnTx() for serial communication to embOSView corrected.
   The transmission handler for communication with embOSView might have sent incorrect data to embOSView, because internal control state was updated after sending the data.
   The problem occured on a new embOS port for a specific CPU only and is fixed with version 3.32k.

Version 3.32j

None.

Known problems/limitations

Version 3.32j

None.

Release history

Version	Release date	Short explanation
V3.32o	30. Apr 2007	OS_Unuse() error handling improved. Enter-/LeaveIntStack corrected.
V3.32l1	02. Apr 2007	Stack switch corrected.
V3.32l	28. Mar 2007	Round robin switching corrected.
V3.32j	01. Mar 2007	First version with release history

Miscellaneous

This document was first released with version 3.32j of the software.
Software released earlier is documented internally. This information is available at request.