Wakeup & Sleep Mode Handling - AUTOSAR Classic BSW

CAN Wakeup Path

CAN Wakeup Sequence

  Wakeup frame on CAN bus
       │  CanDrv interrupt → CanIf_CheckWakeup(ControllerId)
       ▼
  EcuM_SetWakeupEvent(ECUM_WKSOURCE_CAN0)
  EcuM starts validation timer (EcuMValidationTimeout = 200 ms)
       │  Waits for valid CAN frame to confirm real traffic
       ▼
  EcuM_ValidateWakeupEvent(ECUM_WKSOURCE_CAN0)
  ComM_EcuM_WakeUpIndication(CAN0)
       ▼
  ComM: FULL_COM → BswM_ComM_CurrentMode(COMM_FULL_COM)
       ▼
  BswM enables COM Tx/Rx PDU groups — communication resumes

CanSM Network State Transitions

ComM Request	CanSM Action	Bus State
COMM_NO_COM	Controller STOPPED → SLEEP; TJA1043 standby	Passive — Tx off; wakeup detection active
COMM_SILENT_COM	Controller STARTED; Tx disabled	Rx only — partial networking pre-filter check
COMM_FULL_COM	Controller STARTED; Tx enabled	Full bidirectional CAN communication

Low-Power Entry Sequence

CBswM_SleepActions.c

void BswM_GoSleep_ActionList(void)
{
    Com_IpduGroupStop(COM_IPDUGROUP_ALL_TX); /* stop Tx */
    ComM_RequestComMode(COMM_USER_ECU_SLEEP, COMM_NO_COM);
    /* BswM polls CanSM: NO_COM → fire GoSleep phase 2 */
    NvM_WriteAll();
    /* After NvM WriteAll NVM_REQ_OK: */
    EcuM_GoSleep(ECUM_SLEEP_MODE_STANDBY);
}

Partial Networking (PN) — ISO 11898-6

PN Config Parameter	Description
CanNmPnEnabled	Enable PN filter checking in CanNm
CanNmPnFilterMaskByte[N]	8-byte filter mask — bits=1 are checked against NM PDU PNI bits
CanNmPnInfoByte	Byte offset in NM PDU containing the PN info bits
CanIf_PnFilter	Hardware acceptance filter passing only NM PDUs matching PN criteria

Summary

The sleep/wakeup cycle is the most timing-sensitive mode transition in AUTOSAR CP. EcuM validation timeout, ComM mode sequencing, NvM WriteAll completion, and CanSM state machine all must complete within the OEM-specified sleep latency budget. Partial networking prevents nuisance wakeups from unrelated CAN traffic.

🔬 Deep Dive — Core Concepts Expanded

This section builds on the foundational concepts covered above with additional technical depth, edge cases, and configuration nuances that separate competent engineers from experts. When working on production ECU projects, the details covered here are the ones most commonly responsible for integration delays and late-phase defects.

Key principles to reinforce:

Configuration over coding: In AUTOSAR and automotive middleware environments, correctness is largely determined by ARXML configuration, not application code. A correctly implemented algorithm can produce wrong results due to a single misconfigured parameter.
Traceability as a first-class concern: Every configuration decision should be traceable to a requirement, safety goal, or architecture decision. Undocumented configuration choices are a common source of regression defects when ECUs are updated.
Cross-module dependencies: In tightly integrated automotive software stacks, changing one module's configuration often requires corresponding updates in dependent modules. Always perform a dependency impact analysis before submitting configuration changes.

🏭 How This Topic Appears in Production Projects

Project integration phase: The concepts covered in this lesson are most commonly encountered during ECU integration testing — when multiple software components from different teams are combined for the first time. Issues that were invisible in unit tests frequently surface at this stage.
Supplier/OEM interface: This is a topic that frequently appears in technical discussions between Tier-1 ECU suppliers and OEM system integrators. Engineers who can speak fluently about these details earn credibility and are often brought into critical design review meetings.
Automotive tool ecosystem: Vector CANoe/CANalyzer, dSPACE tools, and ETAS INCA are the standard tools used to validate and measure the correct behaviour of the systems described in this lesson. Familiarity with these tools alongside the conceptual knowledge dramatically accelerates debugging in real projects.

⚠️ Common Mistakes and How to Avoid Them

Assuming default configuration is correct: Automotive software tools ship with default configurations that are designed to compile and link, not to meet project-specific requirements. Every configuration parameter needs to be consciously set. 'It compiled' is not the same as 'it is correctly configured'.
Skipping documentation of configuration rationale: In a 3-year ECU project with team turnover, undocumented configuration choices become tribal knowledge that disappears when engineers leave. Document why a parameter is set to a specific value, not just what it is set to.
Testing only the happy path: Automotive ECUs must behave correctly under fault conditions, voltage variations, and communication errors. Always test the error handling paths as rigorously as the nominal operation. Many production escapes originate in untested error branches.
Version mismatches between teams: In a multi-team project, the BSW team, SWC team, and system integration team may use different versions of the same ARXML file. Version management of all ARXML files in a shared repository is mandatory, not optional.

📊 Industry Note

Engineers who master both the theoretical concepts and the practical toolchain skills covered in this course are among the most sought-after professionals in the automotive software industry. The combination of AUTOSAR standards knowledge, safety engineering understanding, and hands-on configuration experience commands premium salaries at OEMs and Tier-1 suppliers globally.