Automotive embedded systems part3 v1
- 1. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Automotive Embedded Systems part3 (OSEK/VDX) Cont. ENG.KEROLES SHENOUDA 1
- 2. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OSEK/VDX Operating System it's time to wake up 2
- 3. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Extended tasks THE TASK THAT ARE ABLE TO WAIT FOR AN EVENT 3
- 4. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system States of an extended task 4
- 5. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system event An event is like a flag that is raised to signal something just happened. An event is private: It is a property of an Extended Task. Only the owning task may wait for the event. It is a N producers / 1 consumer model Any task (extended or basic) or Interrupt Service Routines Category 2 may invoke the service which set an event. One task (an only one) may get the event (ie invoke the service which wait for an event. An Extended Task may wait for many events simultaneously The first to come wakes up the task. an event corresponds to a binary mask: 0x01, 0x02, 0x04, ... 5
- 6. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Event mask Operation: Event X signaling : ev_set |= mask_X; Is event X arrived ? : ev_set & mask_X; Wait for event X : ev_wait | mask_X; Clear event X : ev_set &= ~mask_X; In practice, these operations are done in a simpler way by using the following services. 6
- 7. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Events’ services StatusType SetEvent(TaskType <TaskID>, EventMaskType <Mask>); Events of task <TaskID> are set according to the <Mask> passed as 2nd argument. StatusType is an error code: E_OK: no error; E_OS_ID: invalid TaskId; E_OS_ACCESS: TaskID is not an extended task (not able to manage events); E_OS_STATE: Events cannot be set because the target task is in the SUSPENDED state. This service is not blocking and may be called from a task or an ISR2 7
- 8. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Events’ services StatusType ClearEvent(EventMaskType <Mask>); The events selected by <Mask> are cleared. should be called by the owning task (only); StatusType is an error code: E_OK: no error; E_OS_ACCESS: The calling task is not an extended one (so it does not mabage events); E_OS_CALLEVEL: The caller is not a task. non-blocking service. 8
- 9. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Events’ services StatusType GetEvent(TaskType <TaskId>, EventMaskRefType event); The event mask of the task <TaskId> is copied to the variable event (A pointer to an EventMaskType is passed to the service); StatusType is an error code: E_OK: no error; E_OS_ID: invalid TaskID; E_OS_ACCESS: TaskID is nor an extended task; E_OS_STATE: Events may not be copied because the target task is in the SUSPENDED state. Non-blocking service, my be called from a task or an ISR2 9
- 10. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Events’ services StatusType WaitEvent(EventMaskType <EventID>); Put the calling task in the WAITING state until one of the events is set. May be called by the event owning (extended) task only; StatusType is an error code: E_OK: no error; E_OS_ACCESS: The calling task is not an extended one; E_OS_RESOURCE: The task has not released all the resources (will be explained later); E_OS_CALLEVEL: The caller is not a task Blocking service. 10
- 11. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Lab4: extended task based on event #LEARN_IN_DEPTH 11
- 12. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Lab4 12 Create two tasks T1 and T2 T1 is basic task (sequential task) T2 is Extended task based on event ev1 T2 priority > T1 The Autosatrt is enabled for both T1 and T2 Send a messages for Both T1 and T2 by writing on 7-segment See the following code and expect what happen on the Physical Board
- 13. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Let us first, write the oil file 13
- 15. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system See the following code and expect what happen on the Physical Board 15 Draw a Task Timeline
- 16. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Lab4.c 16 #Learn In Depth expect what happen on the Physical Board
- 17. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Let us see the Solution 17
- 18. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Learn in Depth what happen 18 T2 is an extended task. During A period, T2 is running and T1 is ready, because T2_priority > T1_priority
- 19. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system 19 Then T2 wait for E1 and blocks. T1 runs (B period) Learn in Depth what happen
- 20. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system 20 T1 will pull on the PB2 If it is pressed then will Set the E1 (event) Learn in Depth what happen
- 21. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system 21 Then will press the PB2 Learn in Depth what happen
- 22. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system 22 Then will press the PB2 T2 is released and since P(T2) > P(T1), T2 runs (C period), Learn in Depth what happen
- 23. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system 23 clears E1 and continues to run (D period). Learn in Depth what happen
- 24. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system 24 Will Conten. Learn in Depth what happen
- 25. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Learn in Depth what happen 25
- 27. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Interrupts 2 kinds of interrupts (Interrupt Service Routine or ISR) are defined in OSEK. Level 1 interrupts are very fast; depends on the hardware capabilities of the micro-controller; are not allowed to do a system call; usually difficult to port to another micro-controller; Level 2 interrupts are not as fast as level 1 interrupts are allowed to do some system calls (activate a task, get a resource, ...) 27
- 28. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Kindly Note 28 the execution time of an ISR must be short because it delays the execution of tasks.
- 29. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Interrupt 29 ISR category 1 The ISR does not use an operating system service8. After the ISR is finished, processing continues exactly at the instruction where the interrupt has occurred, i.e. the interrupt has no influence on task management. ISRs of this category have the least overhead. ISR category 2 The OSEK operating system provides an ISR-frameto prepare a run-time environment for a dedicated user routine. During system generation the user routine is assigned to the interrupt.
- 30. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Priority 30 ISR1 Are not allowed to do system calls; • ISR1 are ignored by the operating system and defined as classical interrupts: • Init interrupt registers of the hardware peripheral; • Init the related interrupt mask • Do not touch the other interrupt masks (which are managed by the operating system).
- 31. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Priority 31 ISR2 May (must?) do system calls (activate a task, get a resource, …) • Roughly the same behavior as a task • they have a priority (greater than the higher priority of tasks). ISR2 priority is a logical one and not be related to the hardware priority level. • they have a context (registers, stack, …) • In addition an ISR2 • is associated to a hardware interrupt (triggered by an event) To use an ISR2, it is necessary to • declare it in the OIL file with the interrupt source identifier (depends on the target platform) to indicate where the interrupt handler is installed; • initialize the related interrupt registers of the peripheral which will trigger the interrupt.
- 34. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Counters and Alarms OSEK/VDX Operating System Provides support for processing recurring events. The recurring events (sources) are registered by implementation specific counters. Based on the counters the OSEK OS provides alarm mechanisms to the application. 34 Activate a task Set an event
- 35. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Counters and Alarms cont. 35 Goal: perform an “action” after a number of “ticks” from an hardware device: For example periodic activation of a task with a hardware timer Counter Activate a taskSet an event
- 36. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system The counters The counter is an abstraction of the hardware “tick” source (timer, interrupt source, ...) The “tick” source is heavily dependent of the target platform; The counter is a standard component; At least one counter is available: SystemCounter No system call to modify the counters. Their behavior are masked by the alarms. A hardware interrupt must be associated to a counter 36 CPU Interrupt controller PIT Periodic interrupt timer Other Modules SOC
- 37. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system The counters Cont. A counter defines 3 values 37 The maximum value of the counter (MaxAllowedValue) The counter restart to 0 after reaching MaxAllowedValue A division factor (TicksPerBase): for instance with a TicksPerBase equal to5, 5 ticks are needed to have the counter increased by 1; (MINCYCLE)The minimum number of cycles before the alarm is triggered Count = 0 Count = MaxAllowedValue @count = MINCYCLE alarm is happened
- 38. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OIL description of a counter COUNTER generalCounter { TICKSPERBASE = 10; MAXALLOWEDVALUE = 65535; MINCYCLE = 128; }; 38 number of “ticks” (from the interrupt source) needed to have the counter increased by one. Count = 0 Count = 1 Count = 2 TICKSPERBASE = 10 ticks Maximum value of the counter. This value is used by the OIL compiler to generate the size of the variable used to store the value of the counter Count = MAXALLOWEDVALUE = 65535; minimum interval between 2 triggering of the alarm.
- 39. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system The Alarms An alarm is connected to a counter an performs an action. An alarm is associated to 1 counter A counter may be used for several alarms When the counter reach a value of the alarm (CycleTime, AlarmTime), the alarm expires and an action is performed: Activation of a task; Signalization of an event; alarm-callback routine 39 Activate a task Set an event alarm-callback routine
- 40. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Alarm-callback routines Alarm-callback routines can have neither parameter nor return value. The following format of the alarm-callback prototype shall apply: ALARMCALLBACK(AlarmCallbackRoutineName); Example for an alarm-callback routine: ALARMCALLBACK(BrakePedalStroke) { /* do application processing */ } The processing level of alarm-callback routines is the one used by the scheduler, or ISR, depending on implementations 40
- 41. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Example 41 Delta time = 6 Delta time = 6 Delta time = 6
- 42. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Counters/Alarms Counters d Alarms may be started and stopped dynamicallyo not have system calls. Alarms’ services SetAbsAlarm SetRelAlarm CancelAlarm GetAlarm GetAlarmBase 42
- 43. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system SetAbsAlarm StatusType SetAbsAlarm ( AlarmType <AlarmID>, TickType <start>,TickType <cycle>) AlarmID is the id of the alarm to start. start is the absolute date at which the alarm expire cycle is the relative date (counted from the start date) at which the alarm expire again• If 0, it is a one shot alarm StatusType is an error code: E_OK: no error; E_OS_STATE: The alarm is already started; E_OS_ID: The AlarmID is invalid. E_OS_VALUE: start is < 0 or > MaxAllowedValue and/or cycle is <MinCycle or > MaxAllowedValue. 43
- 44. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system SetRelAlarm StatusType SetRelAlarm ( AlarmType <AlarmID>, TickType <increment>,TickType <cycle>) AlarmID is the id of the alarm to start. increment is the relative date at which the alarm expire cycle is the relative date (counted from the start date) at which the alarm expire again. If 0, it is a one shot alarm StatusType is an error code: E_OK: no error; E_OS_STATE: The alarm is already started; E_OS_ID: The AlarmID is invalid. E_OS_VALUE: increment is < MinCycle or > MaxAllowedValue and/or cycle is < MinCycle or > MaxAllowedValue. 44
- 45. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system CancelAlarm Stop an alarm. StatusType CancelAlarm (AlarmType <AlarmID>) AlarmID is the id of the alarm to stop. StatusType is an error code: E_OK: no error; E_OS_NOFUNC: The alarm is not started; E_OS_ID: The AlarmID is invalid. 45
- 46. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system GetAlarm Get the remaining ticks before the alarm expires StatusType GetAlarm ( AlarmType <AlarmID>, TickRefType <tick>) AlarmID is the id of the alarm to get. tick is a pointer to a TickType where GetAlarm store the remaining ticks before the alarm expire. StatusType is an error code: E_OK: no error; E_OS_NOFUNC: The alarm is not started; E_OS_ID: The AlarmID is invalid. 46
- 47. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system GetAlarmBase Get the parameters of the undelying counter. StatusType GetAlarmBase ( AlarmType <AlarmID>, AlarmBaseRefType <info>) AlarmID is the id of the alarm. info is a pointer to an AlarmBaseType where GetAlarmBase store the parameters of the underlying counter. StatusType is an error code: E_OK: no error; E_OS_ID: The AlarmID is invalid. 47
- 48. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OIL description of an alarm 48 ALARM alarm_1 { COUNTER = generalCounter; ACTION = ACTIVATETASK { TASK = task_1; } ; AUTOSTART = TRUE { ALARMTIME = 10; CYCLETIME = 5000; APPMODE = std; }; }; action to be performed by the alarm. Here, activation of task task_1. The alarm is triggered à 10 It is a periodic alarm which is triggered every 5000 counter tick
- 49. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Lab5 (Periodic task by Alarm) LEARN IN DEPTH 49
- 50. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system lab5 Led 0 >>PORTA pin 4 Led 1 >> PORTA pin 5 Buzzer >> PORTD pin 7 Write a periodic task (extended task) depends on Alram take action (activate the periodic task ) with CYCLETIME = 512 counter cycles. The counter here is SystemCounter. The periodic task responsible on increment seven seg and toggle led 1 For each alarm. Also once the Count value reached to (x == 10|| x==30||x ==50||x==70|| x==90) Then will enable led 0 and the buzzer for only 1 count. The last thing change CYCLETIME and expect what happens ? 50
- 62. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Write the C code LEARN IN DEPTH 62
- 64. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Change the cycle time in oil file and see what will happen ? LEARN IN DEPTH 64
- 66. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Accessing shared resources Hardware and software resources may be shared between tasks (an optionally between tasks and ISR2 in OSEK). Resource management ensures that two tasks cannot occupy the same resource at the same time. priority inversion can not occur. deadlocks do not occur by use of these resources. two tasks or interrupt routines cannot occupy the same resource at the same time. 66
- 67. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Example of an unprotected software resource (global variable): 67 val may contain 2 … or 1 non determinism
- 68. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Priority inversion on occupying semaphores This means that a lower-priority task delays the execution of higher-priority task. sequencing of the common access of two tasks to a semaphore (in a full preemptive system, task T1 has the highest priority) Task T4 which has a low priority, occupies the semaphore S1. T1 preempts T4 and requests the same semaphore. As the semaphore S1 is already occupied, T1 enters the waiting state. Now the low-priority T4 is interrupted and preempted by tasks with a priority between those of T1 and T4. T1 can only be executed after all lower-priority tasks have been terminated, and the semaphore S1 has been released again. Although T2 and T3 do not use semaphore S1, they delay T1 with their runtime. 68
- 69. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_systemDeadlock situation using semaphores In this case deadlock means the impossibility of task execution due to infinite waiting for mutually locked resources The following scenario results in a deadlock: Task T1 occupies the semaphore S1 and subsequently cannot continue running, e.g. because it is waiting for an event. Thus, the lower-priority task T2 is transferred into the running state. It occupies the semaphore S2. If T1 gets ready again and tries to occupy semaphore S2, it enters the waiting state again. If now T2 tries to occupy semaphore S1, this results in a deadlock 69
- 70. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OSEK Priority Ceiling Protocol To avoid the problems of priority inversion and deadlocks the OSEK operating system requires following behavior: At the system generation, to each resource its own ceiling priority is statically assigned. The ceiling priority shall be set at least to the highest priority of all tasks that access a resource or any of the resources linked to this resource If a task requires a resource, and its current priority is lower than the ceiling priority of the resource, the priority of the task is raised to the ceiling priority of the resource. If the task releases the resource, the priority of this task is reset to the priority which was dynamically assigned before requiring that resource. 70
- 71. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OSEK Priority Ceiling Protocol (PCP) the mechanism of the priority ceiling. Task T0 has the highest, and task T4 the lowest priority. Task T1 and task T4 want to access the same resource. The system shows clearly that no unbounded priority inversion is entailed. The high-priority task T1 waits for a shorter time than the maximum duration of resource occupation by T4. 71
- 72. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Resource assignment with priority ceiling between preemptable tasks and interrupt services routines. To determine the ceiling priority of resources which are used in interrupts, virtual priorities higher than all tasks priorities are assigned to interrupts 72
- 73. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Resource assignment with priority ceiling between interrupt services routines 73
- 74. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OSEK resources OSEK resources are used to do mutual exclusion between several tasks (or ISR2) to protect the access to a shared hardware or software entity. Example of hardware entity: LCD display; Communication network (CAN, ethernet, … ). Example of software entity: a global variable; the scheduler (in this case, the task may not be preempted). 74
- 75. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OSEK resources Cont. OSEK/VDX offers a RESOURCE mechanism with 2 associated system calls: GetResource ReleaseResource 75
- 76. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system GetResource StatusType GetResource ( ResourceType <ResID> ) ; Get the resource ResID; StatusType is an error code: E_OK: no error; E_OS_ID: the resource id is invalid; E_OS_ACCESS: trying to get a resource that is already in use (it is a design error). A task that « own » the resource may not be preempted by another task that will try to get the resource. 76
- 77. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system ReleaseResource StatusType ReleaseResource ( ResourceType <ResID> ) ; Release the resource ResID; StatusType is an error code: E_OK: no error; E_OS_ID: the resource id is invalid; E_OS_ACCESS: trying to release a resource that is not in use (it is a design error). 77
- 78. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Tasks group This feature allow to mix non-preemptable tasks and preemptable tasks. In the same group all the tasks are seen as non-preemptable by the other tasks of the group. A task having a higher priority of all the tasks of the group (and not part of the group) may preempt any task of the group. This feature uses an internal resource for each group: The internal resource is got automatically when the task start to run; The internal resource is released automatically when the task terminates; An internal resource may not be reference with GetResource() or ReleaseResource(). 78
- 79. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system OIL Description of a resource RESOURCE resA { RESOURCEPROPERTY = STANDARD; }; 79 TASK myTask { PRIORITY = 2; AUTOSTART = FALSE; ACTIVATION = 1; SCHEDULE = NON; RESOURCE = resA; STACKSIZE = 32768; };
- 80. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Lab6: Resources (expect what the output and draw the task timeline) LEARN IN DEPTH 80
- 86. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system Lab6: Resources (expect what the output and draw the task timeline) LEARN IN DEPTH 86
- 92. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system In the next session will take Communication in OSEK/VDX OS LEARN IN DEPTH 92
- 93. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system References Embedded Microcomputer Systems Real Time Interfacing Third Edition Jonathan W. Valvano University of Texas at Austin. MicroC/OS-II the real-time kernel second edition jean j.labrosse. RTOS Concepts http://www.embeddedcraft.org. OSEK/VDX Operating System Specification 2.2.3 AUTOSAR Layered Software Architecture The Trampoline Handbook release 2.0 Trampoline (OSEK/VDX OS) Test Implementation -Version 1.0, Florent PAVIN ; Jean-Luc BECHENNEC 93
- 94. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system References Trampoline:an open platform for (small) embedded systems based on OSEK/VDX and AUTOSAR http://trampoline.rts-software.org/ Jean-Luc Béchennec1;2, Sébastien Faucou1;3 1IRCCyN (Institute of Research in Communications and Cybernetics of Nantes) 2CNRS (National Center for Scientific Research) / 3University of Nantes 10th Libre Software Meeting 94
- 95. https://www.facebook.com/groups/embedded.system.KS/ Follow us Press here #LEARN_IN DEPTH #Be_professional_in embedded_system References Real Time Systems (RETSY) Jean-Luc Béchennec - [email protected] Sébastien Faucou - [email protected] jeudi 12 novembre 15 AUTOSAR Specification of Operating System V5.0.0 R4.0 Rev 3 OSEK - Basics http://taisnotes.blogspot.com.eg/2016/07/osek- basic-task-vs-extended-task.html OSEK OS Session Speaker Deepak V. M.S Ramaiah School of Advanced Studies - Bangalore 1 95