In this article we will discuss about the ECUM (ECU Manager)module, which is responsible for,
- Initialization and de-initialization of basic software drivers, BswM, SchM and the OS. Recent versions of of AUTOSAR do allow minimum initialization by ECUM and the remaining part is initialized by the BSWM module.
- Configuration of SLEEP and SHUTDOWN for the ECU as and when requested.
- Management of ECU wakeup. It also validate the wakeup by differentiating between the erratic and real wakeup events.
There are two variants of ECUM module:
- Flexile ECUM : Flexible ECUM provides the integrator the flexibility to configure partial or fast startup (i.e. startup with limited capabilities), interleaved startup wherein the startup is interleaved between BSW and application, multiple operational states and multi-core support.
- Fixed ECUM : Fixed set of ECU states and transitions between them is sufficient for conventional ECU’s that do not have special requirements such as partial or fast startup. It does not supports multi-core ECU’s.
The functionality of the ECUM module can be divided in different phases from Startup to Shutdown.
Startup Phase : In this phase the BSW modules are initialized. It is divided in to two parts, one before the OS is initialized and the one after OS initialization. In this phase the SchM and BswM are initialized.
UP Phase : This is an Integrator defined phase wherein the ECU goes from State to State and Mode to Mode as defined by the integrator. This phase is entered post OS, SchM and BswM initialization by the ECUM. As this is an integrator defined phase, the integrator has to take care of the NVRAM block restoration and Communication Stack initialization/de-initialization through BSWM. The BSW and SW-Cs run until they are ready for the ECU to be shut down or put to sleep.
Shutdown Phase : This phase is triggered by a call to EcuM_GoDown(). In this phase the NVRAM blocks have to be written back. At the end of this phase the ShutdownOS() is called.
Sleep Phase : The ECU saves energy in the Sleep phase. Typically, no code is executed but power is still supplied, and if configured the ECU is wakeable in this state. The ECU Manager module provides a configurable set of (hardware) sleep modes which typically are a trade off between power consumption and time to restart the ECU. The ECU Manager module wakes the ECU up in response to intended or unintended wakeup events. Since unintended wakeup events should be ignored, the ECU Manager module provides a protocol to validate wakeup events. The protocol specifies a cooperative process between the driver which handles the wakeup source and the ECU Manager.
Off Phase : The ECU enters the OFF state when it is powered down. The ECU may be wakeable in this state but only for wakeup sources with integrated power control. In any case the ECU must be startable.