TechnicalReference_CANdesc_UDS_PSAs

CANdesc
Technical Reference

PSA

Version 1.00.00

Authors: Alexander Ditte
Version:
1.00.00
Status:
released (in preparation/completed/inspected/released)

Technical Reference CANdesc UDS PSA

1 History
Author
Date
Version
Remarks
Alexander Ditte
2007-12-05 1.0
Initial version

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Technical Reference CANdesc UDS PSA

7.2.1
DescGetSessionIdOfSessionState............................................................. 16
8  Glossary .................................................................................................................... 17
9  Contact ...................................................................................................................... 18
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Technical Reference CANdesc UDS PSA

3  Documents this one refers to…
  Technical Reference CANdesc and CANdesc (one for both)
  User Manual CANdesc

User Manual
Technical
Technical
Reference
Reference
General
OEM
You are here

Figure 3-1  Manuals and References for CANdesc
All OEM specific topics with CANdesc are described within this technical reference and the
common part (e.g. features, concepts) is in the generic technical reference.
For faster integration, refer to the user manual CANdesc.
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4 CANdesc Support by Diagnostic Service
There are three possible levels of support provided by CANdesc for any specific diagnostic
request – complete, assisted and basic. The level of support provided by CANdesc varies
according to CANdesc functionality and user selection. All levels of support provide
complete communication handling, including all transport protocol processing and error
handling, diagnostic session and timer management and basic error checking.
“Communication handling includes testing support of service, but also consistency of
service, sub-function and/or identifier combination. Length checking or request is
performed. Validity of addressing is checked.”
Error handling is a significant part of the ECU software. All errors appearing on this level
are handled inside of CANdesc.

4.1 CANdesc

Complete
Complete support means that CANdesc is capable of handling the diagnostic transaction
without requesting support from (calling) the ECU application. The ECU developer need
not provide any code to help implement the diagnostic feature and CANdesc handles all
processing. In case a service modifies states, the application will be notified using event-
callbacks – it does not have to concern about the protocol.
Assisted
Assisted support means that CANdesc is capable of fully parsing request messages and
building response messages, but does not contain the logic necessary to execute the
request or determine signal values. The ECU developer shall provide callbacks for
CANdesc to invoke when needed to fill the logic gaps.
Basic
Basic support means that CANdesc is only capable of identifying that the ECU application
shall process the request. The ECU application may have to provide logic to validate the
request message (length, sub-function/parameter evaluation) and build the response byte-
by-byte.

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10 – Diagnostic Session Control – Assisted
The application shall provide only a function to check whether the session transition is
allowed or not. All other tasks (e.g. response assembling, state management) are
performed by CANdesc.
11 – Ecu Reset – Basic
The application must provide a function that resets the ECU.
14 – Clear Diagnostic Information – Basic
The application must provide a function that clears fault memory.
19 – Read DTC Information – Basic
The application must provide a function that implements the complete access to the fault
memory.
22 – Read Data By Identifier – Complete/Assisted
CANdesc completely implements this service for IDs that map to global variables.
Assisted support is provided for IDs that do not map to global variables (e.g. EEPROM /
I/O Ports).
The so called “multiple identifier in single request” support is handled by CANdesc
completely.
23 – Read Memory By Address – Basic
The application must provide a function that implements the read access to the memory.
27 – Security Access – Basic
The application must provide a function which includes the complete seed/key algorithm.
The state management can be designed to be handled by CANdesc.
2E – Write Data By Identifier – Complete/Assisted
CANdesc completely implements this service for IDs that map to global variables.
Assisted support is provided for IDs that do not map to global variables.
2F – Input Output Control By Identifier – Basic
The application must provide a function which implements the complete I/O control
operations.
31 – Routine Control – Basic
The application must provide a function which implements the complete routine control.
34 – Request Download – Basic
The application must provide a function which implements the complete service. Instead
the Vector FlashBootLoader can be used.
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35 – RequestUpload – Basic
The application must provide a function which implements the complete service. Instead
the Vector FlashBootLoader can be used.
36 – Transfer Data – Basic
The application must provide a function which implements the complete service. Instead
the Vector FlashBootLoader can be used.
37 – Request Transfer Exit – Basic
The application must provide a function which implements the complete service. Instead
the Vector FlashBootLoader can be used.
3D – Write Memory By Address – Basic
The application must provide a function that implements the write access to the memory.
3E – Tester Present – Complete
CANdesc completely implements this service.
85 – Control DTC Setting – Basic
The application must provide a function that controls the fault memory storage.

Diagnostic services not listed are not supported in any way by CANdesc and must be
implemented entirely by the ECU developer as a workaround.

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5 How
to…
There are some important use cases you have to consider in order to fulfill the PSA
diagnostic requirements. CANdesc offers special APIs and mechanisms to help your
application to realize these requirements and here you will find out how to do this.

5.1 …get the Id of the current active session
PSA defines no dedicated parameter identifier for reporting the current active diagnostic
session in the ECU, but if required you can use CANdesc to help you:
The CANdesc APIs for state access (i.e. DescGetStateSession()) returns the current
session, but it is only an internal representation of the session not the session identifier. So
you cannot use the return value of this API for that report.
To get the session Id your application shall use the API DescGetSessionIdOfSessionState
that converts a session state internal representation into its corresponding session Id (e.g.
for the default session the state is 0x01, the session Id - 0x01, but for the extended
session the state representation is 0x04, the session Id – 0x03).

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6 CANdesc
API
categories
CANdesc can be instantiated in case the configuration requires multiple diagnostic
instances or/and parallel service processing. In order to offer maximum optimization for the
single instance configurations there are two categories of CANdesc API.

Info
Currently Multiple Context is NOT relevant for PSA.

6.1 Single
Context
In this configuration, the run-time and code overhead of an indexed operation mode is
reduced to a minimum.
6.2 Multiple
Context
In this configuration, the code is using additional handles for exact addressing and
recognition of the used API.

For PSA there it depends on the configuration if a multi- or single-instance
diagnostics will be used. To lower the development effort of your application and to
be independent of the current configuration, please use the special API wrappers as
described below.

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6.3  API Context Abstraction
The following chapters describe the main use-cases where the abstraction-macros can be
used.

6.3.1  Direct parameter usage
This category is usable only in API with dedicated context parameter (e.g. Pre-
/PostHandlers, etc.)

6.3.1.1 DESC_CONTEXT_PARAM_VALUE
Use this macro if you have to access an array in your application that is dependent of the
CANdesc running context
Example:
void ApplDescPreHandlerXY(DESC_CONTEXT_FORMAL_PARAM_DEF_ONLY)
{
  applDescState[DESC_CONTEXT_PARAM_VALUE] = active;
}

6.3.1.2 DESC_CONTEXT_PARAM_ONLY
Use this macro if you have to call a context dependent CANdesc API that have only the
context handle parameter
Example: DescRingBufferStart(DESC_CONTEXT_PARAM_ONLY);

6.3.1.3 DESC_CONTEXT_PARAM_FIRST
Use this macro if you have to call a context dependent CANdesc API that have at least
one additional to the context handle parameter
Example: DescSetNegResponse(DESC_CONTEXT_PARAM_FIRST kDescNrcGeneralReject);
Caution
Please note, that there shall be no comma after the macro!!!

6.3.2 Function
declaration/definition usage
This category is useful if you declare/define functions that are context dependent.

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6.3.2.1 DESC_CONTEXT_FORMAL_PARAM_DEF_ONLY
You can use this macro in a function declaration that is context dependent and has only
parameter - the context handle.
Example: void ApplDescPreHandlerXY(DESC_CONTEXT_FORMAL_PARAM_DEF_ONLY);

6.3.2.2 DESC_CONTEXT_FORMAL_PARAM_DEF_FIRST
You can use this macro in a function declaration that is context dependent and has at least
one additional parameter except the context handle one.
Example:
void ApplDescCheckSessionTransition(DESC_CONTEXT_FORMAL_PARAM_DEF_FIRST DescStateGroup
newState, DescStateGroup formerState);
Caution
Please note, that there shall be no comma after the macro!!!

6.3.3 Universal context wrapper
This category is useful in any call-back or call of an API that is context dependent.

6.3.3.1 DESC_CONTEXT_PARAM_WRAPPER_INDEX(contextConst)
This macro is equivalent to the DESC_CONTEXT_PARAM_VALUE one but can take any
expression or identifier as a parameter name.
Example: applDescState[DESC_CONTEXT_PARAM_WRAPPER_INDEX(MyContextVariable)] = active;

6.3.3.2 DESC_CONTEXT_PARAM_WRAPPER_ONLY(contextConst)
This macro is equivalent to the DESC_CONTEXT_PARAM_ONLY one but can take any
expression or identifier as a parameter name.
Example: DescProcessingDone(DESC_CONTEXT_PARAM_WRAPPER_ONLY(pMsgContext->iContext));

6.3.3.3 DESC_CONTEXT_PARAM_WRAPPER_ONLY(contextConst)
This macro is equivalent to the DESC_CONTEXT_PARAM_FIRST one but can take any
expression or identifier as a parameter name.
Example:
DescSetNegResponse(DESC_CONTEXT_PARAM_WRAPPER_FIRST(pMsgContext->iContext)
kDescNrcGeneralReject);
Caution
Please note, that there shall be no comma after the macro!!!

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6.3.4 Utility
This category is useful in any call-back or call of an API that uses a context dependent
API.
6.3.4.1 DESC_CONTEXT_PARAM_DEF_LOCAL
This defines a local context variable in a function, so you can use all the above macros
without name incompatibility issues.
Example:
void ApplTest(void)
{
DESC_CONTEXT_PARAM_DEF_LOCAL
applDescState[DESC_CONTEXT_PARAM_VALUE] = active;
}

6.3.4.2 DESC_CONTEXT_PARAM_DUMMY_USE
If some times you don't need to use the dedicated context handle parameter, you can use
this macro to avoid warnings of not referenced function parameter.
Example:
void ApplDescPreHandlerXY(DESC_CONTEXT_FORMAL_PARAM_DEF_ONLY)
{
DESC_CONTEXT_PARAM_DUMMY_USE /* Ignore warnings */
}

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7 Functions
7.1 Administrative
Functions
7.1.1 DescInitPowerOn
DescInitPowerOn
Is Reentrant
Is callback
Prototype
Any Context
void DescInitPowerOn (DescInitParam initParameter)
Parameter
initParameter
•
‘kDescPowerOnInitParam’ : Default initialization
Return code
-
-
Functional Description
PowerOn Initialization of the CANdesc.
This function has to be called before all other functions of CANdesc once after PowerOn.
Pre-conditions
CAN-driver via CanInitPowerOn() and the TransportLayer via TpInitPowerOn() are
initialized correctly.
Call context
Background-loop level with global disabled interrupts
Particularities and Limitations
  The DescInitPowerOn (initParameter) shall be called after the TpInitPowerOn() was called
(please, refer the /TPMC/ documentation), otherwise the reserved diagnostic connection will be
lost.
  DescInitPowerOn (initParameter) calls internally DescInit() for further initializations

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7.1.2 DescInit
DescInit
Is Reentrant
Is callback
Prototype
Any Context
void DescInit (DescInitParam initParameter)
Parameter
initParameter
•
‘kDescPowerOnInitParam’ : Default initialization
Return code
-
-
Functional Description
Re-initialization of CANdesc.
This function can be called to re-initialize CANdesc (e.g. after WakeUp). All internal states
will be set to default.
Pre-conditions
CANdesc has been once initialized by DescInitPowerOn().
Call context
Background-loop level with global disabled interrupts
Particularities and Limitations
-

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7.2 Help
functions
7.2.1 DescGetSessionIdOfSessionState
DescGetSessionIdOfSessionState
Is Reentrant
Is callback
Prototype
Any Context
DescMsgItem DescGetSessionIdOfSessionState (DescStateGroup sessionState)
Parameter
sessionState
- Shall be one of the valid session states (i.e. the value of the
API DescGetStateSession() ).
Return code
DescMsgItem
- Is the corresponding session identifier value.
Functional Description
This function provides a conversion from a session state to its corresponding session
identifier (e.g. calling this function with parameter kDescStateSessionDefault will return
0x01).
Pre-conditions
-
Call context
-
Particularities and Limitations
-

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8 Glossary

Abbreviation Description

CANdesc
CAN Diagnostic Embedded Software Component
Basic implementation variant
RCR-RP
Request Correctly Received – Response Pending
P2
Maximum delay time before the first RCR-RP will be sent
(50ms by UDS)
P2* (P2Ex)
Maximum delay time before the second RCR-RP will be
sent (5000ms by UDS)
SID
Service Identifier

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9 Contact
Visit our website for more information on

> News
> Products
> Demo software
> Support
> Training data
> Addresses

www.vector-informatik.com
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Document Outline

Last modified July 6, 2025: Initial commit (5e3f2e6)