[overview of AUTOSAR three RTE]

1 RTE summary

RTE Provides SWC Operating environment .

RTE Its function is a bit like an express transfer station or a telephone operator （ It's the kind in the last world that you have to call the operator first , Then transfer the telephone line to the destination through the operator ）, Its function is to make a SWC Information through RTE Connect to other SWC perhaps BSW On . And RTE It has the function of managing this information , For example, received SWC Busy （ The subscriber you dialed is busy ）, that RTE Responsible for sending messages SWC wait for , Or do something else ;RTE Also trigger SWC, It's like receiving at this time SWC Sleeping , Sent at this time SWC Send a message , that RTE It is necessary to put the received SWC Wake up .

2 RTE effect

• Provide cross ECU/ECU Internal communication management .

• Provide right runnable Management function of （ Trigger 、 Wake up, etc , In short, it is runnable Need to map to Task Run on , And this mapping is through RTE actualized ）.

• We didn't mention before VFB（ Virtual function bus ）,RTE Namely VFB The concrete realization of .

• stay Vector In the tool chain ,RTE It's generated automatically .

2.1 RTE Yes Runnables Operation support of

• adopt RTE to runnable Provide departure events
• adopt RTE to runnable Provide the required resources
• take BSW and SWC Do isolation

2.1.1 runnable The trigger condition of

•	 Initialize event ： Initialize auto trigger 
•	 Timer event ： Give a cycle timer , It's time to trigger 
•	 Receive data event （S/R）：Receiver Port  Once the data is received , It triggers 
•	 Receive data error event （S/R）
•	 Data sending completion event （S/R）：Send Port  Send complete , It triggers 
•	 Operation call event （C/S）： When the function is called 
•	 The asynchronous service returns an event （C/S）： I said before C/S It can run asynchronously , That is, when I call a Server function , But I call asynchronously .
	 Then the function to be dropped runs in parallel with the current running program as a thread ,
	 When the called function finishes running, it returns （Return） When , At this time, the asynchronous service return event is triggered 
•	 Mode switching event 
•	 Mode switching response event 

2.2 RTE Yes Ports The support of

2.2.1 features

Play the role SWCs and BSW Communication channels

• As VFB The concrete realization of
• As S/R Communication implementation of interface
• As C/S Communication implementation of interface
• ECU Internal communication / Span ECU（ adopt COM）
• Realization AR-COM The callback function of , The concrete realization is in SWC Done in ,RTE Responsible for completing this callback mechanism

Other characteristics

• Provides a mechanism to achieve data consistency
• Support simple and complex data types
• Yes SWC Instantiation of type

2.2.2 S/R Different ways of interface

1. Call directly （Direct）

It is equivalent to having a global variable ,runnable You can read and write this variable directly

Std_ReturnType Rte_Read_<port>_<data> (<DataType> *data)
Std_ReturnType Rte_Write_<port>_<data> (<DataType> data)

2. Cache call （Buffered）

It is equivalent to copying global variables to a runnable In local variables of , Then operate on this local variable , Finally, assign this local variable to the global variable . stay runnable During the operation of this local variable , Global variables will not change .

<DataType> Rte_IRead_<r>_<port>_<data> (void)
void Rte_IWrite_<r>_<port>_<data> (<DataType> data)

3. Queue calls （Queued）

Because there is more than one data , Is a set of queue data , Just like our commonly used serial port FIFO. therefore , You can set cyclic reception or wait for reception , There is timeout management when waiting .

Std_ReturnType Rte_Receive_<port>_<data> (<DataType> *data)
Std_ReturnType Rte_Send_<port>_<data> (<DataType> data)

2.2.3 Span ECU The way

If it is cross ECU Data transmission of . that , I am here runnable Use in Rte_Write__() After such a function , Will need to go ：
runnable(ECU1) ->RTE (ECU1) ->BSW (ECU1) -> External bus ->BSW (ECU2) ->RTE (ECU2)->runnable (ECU2)

Com_SendSignal()
Com_ReceiveSignal()

2.2.4 C/S Different ways of interface

A synchronous invocation

Synchronous call is actually the same function we usually call , It is equivalent to embedding the called function code into the currently called function code to run

// Suppose our called function is ：
Std_ReturnType RunnableServer(int *param)
// The calling function that our customers should write is ：
Std_ReturnType Rte_Call_<Port>_RunnableServer(int *param)
// This param Is the variable we want to be manipulated by the called function 

Asynchronous call

An asynchronous call is equivalent to having two threads , A thread runs the contents of our original function , The other is to execute the content of the called function . Then you can read the return result of the called function after a period of time

How to know whether the called function is finished ？ There are three ways ：

1. Cycle test , Just wait there , Wait until the value is returned , In this case, it is almost the same as synchronization , It doesn't make much sense
2. Timeout detection , Set a time , When the time comes, read , Continue to run my program before it arrives
3. Events trigger , When the service function is finished ,RTE Can trigger the original function , Tell it that the called function is finished , You can read the return value

// After executing the following function, you can return the parameters 
Std_ReturnType Rte_Result_<Port>_RunnableServer(int *param)

2.3 RTE Management of data consistency

Data consistency , When multiple users try to access a database at the same time , When their transactions use the same data at the same time , There are four possible scenarios ： Lost update 、 Undetermined correlation 、 Inconsistent analysis and fantasy reading .

Implementation mechanism of data consistency ：

1. utilize RTE management

2. SWC Internal variables

• EAs(ExclusiveAreas, Dedicated area )： It is the following two sentences of code , Equivalent to an off interrupt , The statements that call variables are placed inside , The runtime cannot have more advanced Task Break the protected statement

......
Rte_Enter_<name>();
// Put protected statements here 
Rte_Exit_<name>();
......

• IRVs(Inter-runnablevariables, Cross functional variables )： Or two sentences of code , above EAs The whole code segment is protected , The two sentences here are equivalent to being protected when changing variables , That is, when these two sentences are executed, they are protected .

Rte_IrvWrite_<re>_<name>()
Rte_IrvRead_<re>_<name>()

2.4 RTE Yes Interface Interface

2.4.1 AutoSAR Interface

As I said before S/R and C/S The interface is AutoSAR Interface

characteristic ：

The interface function name is variable , For example, as I said before Std_ReturnType Rte_Read__ (
*data) In this form S/R function , Among them It is the name configured by the user , therefore , The function names of these interfaces can be changed , But the general form is unchanged .

Location ：

SWC<>RTE、RTE<>CDD、RTE<>ECU AB

• ( Here's a word ,ECU AB I didn't talk about , In fact, many sensors 、 The actuators are all here , yes ECU The abstraction of , It can also be seen as SWC Of ,IoHwAb It's in here ). To be clear , As long as it can be regarded as SWC To deal with the , Namely AutoSAR Interface

2.4.2 Standard interface

AutoSAR Stipulated C Language API

characteristic ：

The interface function name is fixed , yes AutoSAR Stipulated .
such as ：Com_SendSignal() WaitEvent() These are API Function name , There can be upper layer calls ,
But it is usually generated by using tool configuration , Those who do upper level applications generally don't care about their specific implementation

Location ：

  The brown one in the figure is the standard interface , To put it bluntly, it's about functions API Call to .

One thing that needs special explanation is ： The arrows in the two red circles in the figure below ,OS and COM It is the only two standard interfaces that allow direct and RTE Connected .
because RTE Many functions of the need to be based on these two modules to achieve ```

2.4.3 standard AutoSAR Interface

AutoSAR Interface , But the name is by AutoSAR Official regulations cannot be modified

characteristic ：

Standard interfaces and AutoSAR The characteristics of the interface have some .
The first is and AutoSAR As the interface , What is offered is C/S、S/R Interface ; Then it is the same as the standard interface , The function name is immutable .
To put it bluntly, it is officially stipulated C/S、S/R Interface , Let's take it as AutoSAR Interface is fine , Never mind the function name

Location ：

 RTE<>Services, Just such a place