FlexRay Transceiver Driver (FrTrcv)

The FlexRay transceiver driver controls the transceiver devices of an ECU via Dio or Spi and offers the modes NORMAL, RECEIVEONLY, STANDBY, and SLEEP in ACTIVE [SWS_FrTrcv_00481]. It sets and reads modes, detects wakeup events via cyclic polling or notification, reports them to EcuM, and provides the wakeup reason. For active stars, it polls bus errors per branch and switches branches off or on. If a mode change fails, it returns E_NOT_OK and leaves the previous state unchanged [SWS_FrTrcv_00323].

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The FlexRay transceiver driver controls the transceiver devices of an ECU. It addresses each device via the zero-based index FrTrcv_TrcvIdx [SWS_FrTrcv_00323]. Toward the bottom, it accesses the hardware via Dio or Spi, depending on the configuration SWS FrTrcv Fig. 10.4 p. 77. In addition, it uses Icu, EcuM, Dem, and Det [SWS_FrTrcv_00334]. Toward the top, FrIf is likely to use the services primarily on behalf of the FlexRay State Manager (interpretation) SWS FrSM p. 20. Question (open)

Context diagram: FrTrcv between FrIf/FrSM, the hardware drivers, and the services EcuM, DEM, and DET. Sources: [SWS_FrTrcv_00334], SWS FrSM p. 20

After power-on, the driver is in NOT_ACTIVE and transitions to ACTIVE with FrTrcv_Init SWS FrTrcv Fig. 7.1 p. 23. The modes NORMAL, RECEIVEONLY, STANDBY, and SLEEP apply there [SWS_FrTrcv_00481]. FrTrcv_SetTransceiverMode transitions between them. If the transition fails, the service returns E_NOT_OK and leaves the previous state unchanged. The driver implements wait times using Tm_BusyWait1us16bit [SWS_FrTrcv_00485]. In STANDBY, the ICU wakeup channels are enabled; in NORMAL, they are disabled [SWS_FrTrcv_00491] [SWS_FrTrcv_00492].

State diagram: The four ACTIVE modes can only be reached after FrTrcv_Init. The edges are partially reconstructed (interpretation). Sources: SWS FrTrcv Fig. 7.1 p. 23, [SWS_FrTrcv_00481]

The driver detects wakeup events in two ways: via cyclic FrTrcv_MainFunction [SWS_FrTrcv_00330] or via notification. After FrTrcv_CheckWakeupByTransceiver, it reports the event to EcuM SWS FrTrcv p. 46. FrTrcv_GetTransceiverWUReason provides the reason, such as FRTRCV_WU_BY_BUS, insofar as the hardware can distinguish it [SWS_FrTrcv_00074]. FrTrcv_ClearTransceiverWakeup clears all pending events [SWS_FrTrcv_00329].

For active stars, optional services query bus errors per branch and switch branches off or back on [SWS_FrTrcv_00419] [SWS_FrTrcv_00442] [SWS_FrTrcv_00443]. For error handling, the following applies:

• Development errors such as FRTRCV_E_UNINIT go to DET [SWS_FrTrcv_00085].
• Runtime errors such as FRTRCV_E_FR_NO_CONTROL_TRCV pass via Det_ReportRuntimeError [SWS_FrTrcv_91001].
• The driver reports Class A and Class B bus errors to DEM or to a configured substitute function [SWS_FrTrcv_00475].

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Role: Hardware Abstraction for FlexRay Transceiver Devices

The FlexRay transceiver driver controls one or more FlexRay transceiver devices of an ECU. All channel-related services select the device via the zero-based index FrTrcv_TrcvIdx, which applies in the context of the driver [SWS_FrTrcv_00323]. The driver offers three groups of services:

• Setting and querying the operating modes [SWS_FrTrcv_00324],
• Handling wakeup events [SWS_FrTrcv_00325] [SWS_FrTrcv_00331],
• Managing individual branches in the case of active stars [SWS_FrTrcv_00419].

FrTrcv_GetVersionInfo explicitly returns the version of the software module and not that of the transceiver hardware SWS FrTrcv p. 43.

Toward the bottom, the driver accesses the device via Dio or Spi. For wakeup notifications, it uses Icu; reports go to EcuM, Dem, and Det [SWS_FrTrcv_00334] [SWS_FrTrcv_00321]. The access type is defined by the choice container FrTrcvAccess: it allows exactly one of the two alternatives, i.e., Dio access or SPI sequence SWS FrTrcv Fig. 10.4 p. 77.

Toward the top, the FlexRay Interface is likely to use the services primarily. The FlexRay State Manager determines the wakeup reason per transceiver of a cluster via FrIf_GetTransceiverWUReason SWS FrSM p. 20. Interpretation: FrIf forwards these requests to FrTrcv. Question Q-29229b532631a6b5 (open) This is consistent with the fact that the shared types in Fr_GeneralTypes.h are protected by FR_GENERAL_TYPES so that multiple transceiver drivers and FrIf can share them SWS FrTrcv p. 34.

Context diagram: FrTrcv is located between FrIf/FrSM and the drivers Dio, Spi, and Icu and reports to EcuM, DEM, and DET. Sources: [SWS_FrTrcv_00334], [SWS_FrTrcv_00485], [SWS_FrTrcv_00330], SWS FrSM p. 20

Operating Modes Between NOT_ACTIVE and ACTIVE

Figure 7.1 of the specification describes the modes as a nested state machine. Within POWER_ON, the driver is in NOT_ACTIVE after power-on and transitions to ACTIVE with FrTrcv_Init() SWS FrTrcv Fig. 7.1 p. 23. Only in ACTIVE do the four values of FrTrcv_TrcvModeType apply: FRTRCV_TRCVMODE_NORMAL, FRTRCV_TRCVMODE_RECEIVEONLY, FRTRCV_TRCVMODE_STANDBY, and FRTRCV_TRCVMODE_SLEEP [SWS_FrTrcv_00481]. The calling layer switches between these modes with FrTrcv_SetTransceiverMode [SWS_FrTrcv_00323].

A mode change proceeds synchronously and is non-reentrant. Transitions to optional states may fail. In that case, the service returns E_NOT_OK, and the previous state is retained SWS FrTrcv p. 39. If the device requires wait times for a state transition, the driver implements them using the timer service Tm_BusyWait1us16bit [SWS_FrTrcv_00485]. FrTrcv_GetTransceiverMode reads the actual state. This service is reentrant and may therefore also be called concurrently [SWS_FrTrcv_00324].

State diagram: Only after FrTrcv_Init can the four ACTIVE modes be reached via FrTrcv_SetTransceiverMode. The selection of transitions is partially reconstructed (interpretation). Sources: SWS FrTrcv Fig. 7.1 p. 23, [SWS_FrTrcv_00481]

Startup and commencement of bus communication

FrTrcv_Init receives a pointer to the selected configuration set and initializes the driver [SWS_FrTrcv_00322]. This separate function initializes variables and hardware resources. Drivers that serve wake-up sources are re-initialized in the restart block, thereby re-arming the triggering mechanism of the wake-up notification SWS FrTrcv p. 37. The driver supports the initialization sequence of the AUTOSAR stack. Interpretation: Within this sequence, the ECU State Manager presumably calls the function. Question Q-93ce1e5987a96873 (open)

The transition to NORMAL affects the wake-up paths. If FrTrcvIcuChannelRef is configured, the driver disables the ICU channels using Icu_DisableNotification [SWS_FrTrcv_00492]. Without this reference, it does not access ICU channels at all [SWS_FrTrcv_00490].

Sequence diagram: Initialization is followed by the transition to NORMAL with busy-wait and optional ICU disabling. A failure leaves the state unchanged. Sources: [SWS_FrTrcv_00322], [SWS_FrTrcv_00323], [SWS_FrTrcv_00485], [SWS_FrTrcv_00492]

Wake-up detection in STANDBY and SLEEP, wake-up reason

Upon transitioning to STANDBY, the driver re-enables the ICU channels [SWS_FrTrcv_00491]. Furthermore, upon every transition to STANDBY, FrTrcv_SetTransceiverMode clears the error history in the transceiver, provided the hardware supports it SWS FrTrcv p. 39.

Additionally, the driver can poll cyclically. For this purpose, it provides FrTrcv_MainFunction via SchM_FrTrcv.h [SWS_FrTrcv_00330]. According to the document passage from R23-11, the function scans all buses in STANDBY and SLEEP for wake-up events and stores detected events internally. The period is defined by the configuration. The function may run synchronously or asynchronously with respect to the FlexRay bus schedule SWS FrTrcv p. 49.

Sequence diagram: Upon the transition to STANDBY, the error history is cleared and ICU notification is enabled. Subsequently, the main function cyclically searches for wake-up events. Sources: [SWS_FrTrcv_00491], [SWS_FrTrcv_00330], SWS FrTrcv p. 49

If the device detects a wake-up via the bus, the underlying SPI or DIO side notifies the driver. This can occur in interrupt context SWS FrTrcv p. 46. If FrTrcv_CheckWakeupByTransceiver is called subsequently [SWS_FrTrcv_00331], the driver reports the event to the ECU State Manager. For this purpose, EcuM_SetWakeupEvent is listed in the list of used interfaces [SWS_FrTrcv_00334]. Interpretation: EcuM presumably triggers the check call within its wake-up sequence. Question Q-d5873691a495bef0 (open)

FrTrcv_GetTransceiverWUReason provides the wake-up reason [SWS_FrTrcv_00325] as a value of FrTrcv_TrcvWUReasonType. Possible values are FRTRCV_WU_BY_BUS, FRTRCV_WU_BY_PIN, FRTRCV_WU_INTERNALLY, or FRTRCV_WU_NOT_SUPPORTED [SWS_FrTrcv_00074]. How finely the reasons are distinguished depends heavily on the hardware SWS FrTrcv p. 42. The document passage of later releases additionally mentions FRTRCV_WU_RESET and FRTRCV_WU_POWER_ON SWS FrTrcv p. 34. The R20-11 requirement text in the payload is truncated at this point.

The FrSM checks the wake-up reason per transceiver for FRTRCV_WU_BY_BUS. In this way, it distinguishes whether no, partial, or complete bus wake-up is present SWS FrSM p. 20. FrTrcv_ClearTransceiverWakeup subsequently clears all pending wake-up events [SWS_FrTrcv_00329]. The call is also permitted when wake-up notification is disabled SWS FrTrcv p. 44.

Sequence diagram: Sequence from hardware notification via the EcuM report to querying and clearing the wake-up reason. The payload does not name the caller of the check function (interpretation). Sources: [SWS_FrTrcv_00331], [SWS_FrTrcv_00325], [SWS_FrTrcv_00329], SWS FrTrcv p. 46

Active stars: Monitoring, disabling, and enabling branches

For transceivers that serve multiple branches as an active star, three additional services exist. They are only available if branches are configured SWS FrTrcv p. 52. All three additionally address the branch via the zero-based index FrTrcv_BranchIdx and are non-reentrant [SWS_FrTrcv_00419] [SWS_FrTrcv_00442] [SWS_FrTrcv_00443].

FrTrcv_GetTransceiverError writes the error state of a branch as uint32 to FrTrcv_BusErrorState. All errors required by the FlexRay EPL that are supported by the hardware can be queried SWS FrTrcv p. 48. Faulty branches are disabled using FrTrcv_DisableTransceiverBranch SWS FrTrcv p. 50. FrTrcv_EnableTransceiverBranch re-enables them synchronously with the FlexRay bus schedule SWS FrTrcv p. 51. If an index is outside the valid range, both switching services return E_NOT_OK, and the branch state remains unchanged [SWS_FrTrcv_00442] [SWS_FrTrcv_00443].

Activity diagram: Error query per branch, disabling of faulty branches, and re-enabling synchronously with the bus schedule. That the calling layer decides is an interpretation. Sources: [SWS_FrTrcv_00419], SWS FrTrcv p. 50, SWS FrTrcv p. 51

Configuration, access type, and partitioning

FrTrcv_ConfigType is an implementation-specific structure [SWS_FrTrcv_00487]. The module contains one or more containers FrTrcvChannel, one per transceiver channel, as well as FrTrcvGeneral SWS FrTrcv p. 59. This document passage from R23-11/R25-11 furthermore only mentions VARIANT-PRE-COMPILE without post-build support. For R20-11, the payload contains no requirement regarding this.

Per transceiver, FrTrcvAccess selects either FrTrcvDioAccess or FrTrcvSpiSequence SWS FrTrcv Fig. 10.4 p. 77. Optional functions can be enabled and disabled at compile time SWS FrTrcv p. 52. FrTrcvIcuChannelRef links the ICU wake-up notification [SWS_FrTrcv_00490]. Using FrTrcvDemReportErrorStatusConfiguration, a custom function with the same signature can be employed instead of Dem_SetEventStatus [SWS_FrTrcv_00475].

In partitioned systems, the module operates as an independent instance per partition. An API call only affects the partition in which it occurs [SWS_FrTrcv_00494]. The module must reject partition assignments that the implementation does not support [SWS_FrTrcv_00497].

Behavior in the event of an error

The development errors are specified [SWS_FrTrcv_00085]:

• FRTRCV_E_FR_INVALID_TRCVIDX (0x01),
• FRTRCV_E_FR_INVALID_BRANCHIDX (0x02),
• FRTRCV_E_UNINIT (0x10),
• FRTRCV_E_PARAM_POINTER (0x15).

They are only reported when development error detection is enabled. Examples are FRTRCV_E_UNINIT for the branch services SWS FrTrcv p. 50 and the NULL pointer for FrTrcv_GetVersionInfo SWS FrTrcv p. 43.

As runtime errors, the driver reports calls in the wrong mode with FRTRCV_E_FR_TRCV_NOT_STANDBY to FRTRCV_E_FR_TRCV_NOT_RECEIVEONLY (0x11 to 0x14). Missing or faulty communication with the device is reported with FRTRCV_E_FR_NO_CONTROL_TRCV (0x16) [SWS_FrTrcv_91001]. These reports run via Det_ReportRuntimeError [SWS_FrTrcv_00493]. FrTrcv_GetTransceiverMode triggers the error FRTRCV_E_FR_NO_CONTROL_TRCV, for example upon an error in transceiver access SWS FrTrcv p. 41.

With E_NOT_OK, the output parameters remain unchanged, such as with FrTrcv_GetTransceiverMode and FrTrcv_GetTransceiverError SWS FrTrcv p. 48. A failed mode change leaves the previous state intact [SWS_FrTrcv_00323].

Activity diagram: Parameter and initialization checks lead to development errors, access errors to a runtime error. The sequence of checks is an interpretation. DET checks only exist when error detection is enabled. Sources: [SWS_FrTrcv_00085], [SWS_FrTrcv_91001], [SWS_FrTrcv_00493]

For production diagnostics, the driver distinguishes two transceiver classes:

• For GPIO-controlled transceivers of Class A, an active ERRN pin (low) signifies "Fail", an inactive pin (high) signifies "Pass" [SWS_FrTrcv_00489].
• For SPI-controlled transceivers of Class B, each set bit 1…9 triggers a bus error [SWS_FrTrcv_00488].

Evaluation takes place upon an unexpected HALT or upon NORMAL_ACTIVE of the controller. In the case of a short circuit on the bus, a "Pass" from the driver alone is not sufficient as proof SWS FrTrcv p. 26. Dem_SetEventStatus is only available with STANDARD_REPORTING [SWS_FrTrcv_00334].

Activity diagram: Pass/Fail evaluation per transceiver class and reporting path to DEM or to the configured replacement function. Sources: [SWS_FrTrcv_00488], [SWS_FrTrcv_00489], [SWS_FrTrcv_00475]

Further detailed evidence

Reference	Classification
[SWS_FrTrcv_00481], SWS FrTrcv Abb. 7.1 S. 23	Operating modes and state machine
[SWS_FrTrcv_00323], SWS FrTrcv S. 39	Mode change, failure, clearing of error history in STANDBY
[SWS_FrTrcv_00322], SWS FrTrcv S. 37	Initialization and restart rule for wake-up sources
[SWS_FrTrcv_00330], [SWS_FrTrcv_00485]	Cyclic polling and wait times
[SWS_FrTrcv_00331], [SWS_FrTrcv_00325], [SWS_FrTrcv_00074], [SWS_FrTrcv_00329]	Wake-up path from detection to clearing
[SWS_FrTrcv_00490], [SWS_FrTrcv_00491], [SWS_FrTrcv_00492]	ICU notification depending on mode
[SWS_FrTrcv_00419], [SWS_FrTrcv_00442], [SWS_FrTrcv_00443]	Branch management for active stars
[SWS_FrTrcv_00085], [SWS_FrTrcv_91001], [SWS_FrTrcv_00493]	Development and runtime errors
[SWS_FrTrcv_00488], [SWS_FrTrcv_00489], [SWS_FrTrcv_00475]	Dem events and reporting path
[SWS_FrTrcv_00487], [SWS_FrTrcv_00494], [SWS_FrTrcv_00497]	Configuration type and partitioning