embOS for Altera NIOS 2 was developed for and with the ALTERA NIOS II IDE and the Software Build Tools V11.1. It comes with an easy to use start project for the NIOS IDE II and a start project for the NIOS Software Build Tools. Software development with JTAG debugger is possible.

Resources and performance data

Memory usage
Kernel size (ROM)	approx. 3000 bytes
Kernel RAM usage	TBD
RAM usage per task control block	TBD
RAM usage per resource semaphore	TBD
RAM usage per counting semaphore	TBD
RAM usage per mailbox	TBD
RAM usage per software timer	TBD
RAM usage event	0 bytes
Min. stack-size per task (RAM)	1200
Timing
Context switch time	TBD
Interrupt latency time	TBD
Kernel CPU usage/TICK	TBD
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 values given above were measured with embOS release build on an NIOS Stratix CPU running at 50MHz.

embOSView offers system analysis during runtime

Available Emulators

• GDB debugger with JTAG support

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Release notes V3.84

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:  NIOS2 GNU V11.1
Assembler: NIOS2 GNU V11.1
Librarian: NIOS2 GNU V11.1
Workbench: NIOS2 IDE V11.1

New features

Version 3.84

1. Support of Vectored interrupt controller added.
   embOS comes with additional code and modified task switching functions which allow usage of the vectored interrupt controller.
   The VIC support is included in the embOS libraries since embOS versin V3.84.
   The VIC is supported without any modification on the target application.
   When the VIC is used in the target CPU, the required modified task switch functions and interrupt support are automatically selected from the embOS library.
2. Update to new embOS sources.
   embOs comes with new features which are described in the generic release notes.

Version 3.82h

1. Update to the new NIOS Software Build Tools V9.1
   With version 9.1 of the NIOS software, new Software build tools are delivered from Altera
   The NIOS projects require the application and a BSP. The BSP replaces the former syslib of the NIOS II IDE projects.
   embOS now comes with a BSP which can be used to add embOS to a project under the new Software build tools.
   An embOS syslib is still delivered for those customers which want to continue working with the NIOS II IDE.
2. Update to new embOS sources.
   embOs comes with new features which are described in the generic release notes.

Version 3.80h

1. Update to new embOS sources.
   embOs comes with new features which are described in the generic release notes.
2. XR libraries delivered for embOS NIOS.
   The XR libraries (eXtreme Release) allow fastest scheduling and may be used for applications which do not need task names or round robin scheduling.

Version 3.60d1

1. embOS interrupts are not nestable per default.
   The interrupt handler for embOS timer tick and the optional UART for embOSView in Rtosint.c were modified to be not nestable per default.
   The configuration switch ALLOW_NESTABLE_INTERRUPTS may be modified to enable nested intrrupts for the embOS system interrupts.

Version 3.60b

1. New generic embOS version 3.60b used
   All new features, improvements and corrections of the new generic embOS sources are listed in the Release_Generic.html document.

Version 3.28p

1. New error handling for version without round robin scheduling
   In debug versions of embOS, OS_Error() is called with error code OS_ERR_TASK_PRIORITY, if a task is created with a priority which is already assigned to an other task.
   OS_Error() is also called with the same errorcode, if a task priority is assigned by call of OS_SetPriority() and the new pririty is already assigned to an other task.
   Round robin switching can be disabled by recompiling sources with OS_RR_SUPPORTED defined as 0.

Version 3.28n

1. embOS library version available
   Now, embOS for NIOS II comes as library version which speeds up project compilation.

Version 3.28l

1. OS_SignalCSemaMax()
   New counting semaphore handling function which specifies a maximum count value.
   This allows counting semaphores used as binary semaphores.

Version 3.28i

1. OS_DeleteRSema()
   New resource semaphore handling function allows to delete resource semaphores during runtime.
   

Version 3.28h

1. Additional error checks in debug builds of embOS
   OS_CreateRSema() now generates an error, when the addressed resource semaphore was already created before.
   OS_CreateCSema() now generates an error, when the addressed counting semaphore was already created before.
   OS_CreateMB() now generates an error, when the mailbox was already created before.
   OS_CreateTimer() now generates an error, when the software timer was already created before.
   OS_MEMF_Create() now generates an error, when the fixed size memory pool was already created before.

Version 3.28g

1. OS_GetSuspendCnt()
   New info function to examine suspension state and suspension count of a task.

Version 3.26

1. Update for new NIOS2 V1.1
   Modified version of ALTERA HAL API functions required an update of embOS for NIOS2 V1.1
2. OS_Terminate() modified
   Task may be terminated anytime, regardless of task state.
   All resources claimed by the terminated task are automatically released.

Version 3.22a

1. OS_PutMailFront() / OS_PutMailFront1
   New mailbox functions to enable LIFO behavior of mailboxes.
2. OS_PutMailFrontCond() / OS_PutMailFrontCond1()
   New conditional mailbox functions to enable LIFO behavior of mailboxes.

Version 3.20

1. NONE.
   Initial release.

Improvements

Version 3.80h

1. embOS scheduler optimized.
   embOs version 3.80 uses internal data structures which allow more effective scheduling and data handling.
   This results in faster context switch times and faster execution of other scheduler operations.

Version 3.60c

1. New generic embOS version 3.60c used
   The new assertion OS_ASSERT_INIT_CALLED() checks whether OS_InitKern() was called before OS_CreateTask() or OS_CreateTaskEx() is called.

Version 3.28n

1. embOS round-robin scheduling may be disabled.
   Round-robin scheduling may be disabled by recompiling sources with OS_RR_SUPPORTED defined as 0.
   This will save some bytes of RAM and ROM and may make sense for small CPUs.

Version 3.28g

1. embOS scheduling simplified
   Task activation and deactivation on "waitable objects" as mailboxes, semaphores, events, fixed size memory blocks now all use the same scheduling method.
   This modification saves ROM and RAM and makes scheduler easier to understand and to maintain.
   Applications which accessed internal data structures of waitable objects directly have to be modified.

Version 3.26

1. NONE

Program corrections

Version 3.28q1

1. Separate Exception stack can not be used.
   The syslib configuration allows selection of a separate exception stack.
   This option can not be used with embOS !
   In previous versions, it was documented that this option may be used when interrupts are not nestable. When separate exception stack was enabled, the task switch from interrupt did not work.
   Now an error message is generated if this option is selected in the system library settings. This problem existed in all previous versions of embOS for NIOS and is fixed with version 3.28q1.
   

Version 3.28q

1. Problem with suspended tasks which were on delay fixed.
   If a task which was on delay was suspended, the delay timer for that task was not handled.
   This might have resulted in additional longer delay when the task was resumed later.
   This problem existed in all previous embOS versions and is fixed with version 3.28q.
   
2. OS_EnterNestableInterrupt() / OS_LeaveNestableInterrupt() corrected.
   For NIOS 2 CPU using standard interrupt handler from ALTERA HAL, OS_EnterNestableInterrupt did not re-enable interrupts correctly.
   When an embOS function was called from within an interrupt handler which used OS_EnterNestableInterrupt(), the embOS function returned with interrupts disabled.
   This problem existed in all previous embOS versions for NIOS 2 and is fixed with version 3.28q.

Version 3.28p

1. OS_Suspend() corrected.
   OS_Suspend() did not work corretly, when the current task was suspended from within an interrupt handler, or from a critical region.
   The application crashed, or called the embOS error handler OS_Error() with error code OS_ERR_INV_TASK (128).
   As OS_Suspend() automatically enters a critical region in debug-trace builds, OS_Suspend() also failed, when it was called to suspend the current task in debug-trace builds of embOS.
   This problem existed in all previous embOS versions and is fixed with version 3.28p.
2. OS_UART interupt handler for embOSView corrected.
   The interrupt handler for communication between embOS and embOSView was corrected.
   The previous version wasted some time inside the interrupt which could slow down the application and increased latency of other interrupts.
   This problem existed in all previous embOS versions and is fixed with version 3.28n.

Version 3.28l

1. OS_MEMF_Free() added
   The function OS_MEMF_Free() was not included in embOS libraries, but was documented in embOS users manual and was also declared in RTOS.h.
   This problem existed in all previous embOS versions and is fixed with version 3.28l.

Version 3.28k

1. OS_MEMF_IsInPool() corrected
   OS_MEMF_IsInPool() failed, if a pointer was checked which pointed to the first address after the memory pool. This pointer was reparted as belonging to the pool.
   This problem existed in all previous embOS versions and is fixed with version 3.28g.

Version 3.28g

1. OS_WakeTask() for trace build corrected
   OS_WakeTask() in trace build disabled task switches.
   This problem existed since version 3.24 and is fixed with version 3.28g.
2. OS_GetMailTimed() / mailbox handling corrected
   During call of OS_GetMailTimed, interrupts were re-enabled too early. If a mail was just put into a mailbox and the timeout occured at the same time, a mailbox internal control variables which managed waiting tasks was set to a wrong value.
   This resulted in wrong mailbox handling and caused task waiting for mail kept suspended, even though, mail was available. This problem existed in all previous versions of embOS and is fixed with version 3.28g.

Version 3.26a

1. OS_MEMF_Release() corrected
   OS_MEMF_Release() might have failed according to absolute address of memory block.
   The problem occured because address calculation was done with 16bit interger value.
   Calculation was modified to use 32bit values to fix the problem.

Version 3.26

1. NONE

Known problems / Limitations

Version 3.60d

1. Separate exception stack can not be used.
   Using embOS, the separate exception stack option must not be enabled in the system library options.

Release history

Version	Release date	Short explanation
V3.84	14 Nov 2011	VIC supported
V3.82h	09 Jul 2010	Update to ne NIOS software tools
V3.80h	28 Jul 2009	New embOS sources 3.80h
V3.60d1	04. Dec 2008	Interrupt handling modified
V3.60d	03. Jun 2008	new embOS sources 3.60d
V3.60c	24. Apr 2008	new embOS sources 3.60c
V3.60b	18. Apr 2008	new embOS sources 3.60b
V3.28q1	09. Jan 2008	new embOS sources 3.28q, corrected version
V3.28q	17. Feb 2006	new embOS sources 3.28q, corrected version
V3.28n	06. Feb 2006	embOS libraries available
V3.28l	09. Nov 2005	new embOS sources 3.28l, corrected version
V3.26	09. Feb 2005	Update for NIOS2 V1.1, new embOS sources 3.26
V3.22	01. Nov 2004	Initial release

Miscellaneous

This document was first released with version 3.26 of the software.
Software released earlier is documented internally.
This information is available at request.