SNIP_CLASSIC_WDGM_SECTION_7_8_Alarm_Clock

7.8 Alarm Clock The ECU Manager module provides an optional persistent clock service which remains "active" even during sleep. It thus guarantees that an ECU will be woken up at a certain time in the future (assuming that the hardware does not fail) and provides clock services for long-term activities (i.e. measured in hours to days, even years). Generally, this service will be realized with timers in the ECU that can induce wakeups. In some cases, external devices can also use a regular interrupt line to periodically wake the ECU up, however. Whatever the mechanism used, the service uses one wakeup source privately. The ECU Manager module maintains a master alarm clock whose value determines the time at which the ECU will be woken up. Moreover the ECU manager manages an internal clock, the EcuM clock, which is used to compare with the master alarm. Note that the alarm wakeup mechanisms are only relevant to the SLEEP phase. SW-Cs and BSW modules can set and retrieve alarm values during the UP phase (and only during the UP phase), which will be respected during the SLEEP phase, however. Compared to other timing/wakeup mechanisms that could be implemented using general ECU Manager module facilities, the Alarm Clock service will not initiate the WakeupRestart Sequence until the timer expires. When the ECU Module detects that its timer has caused a wakeup event, it increments its timer and returns immediately to sleep unless the clock time has exceeded the alarm time. [SWS_EcuM_04069] Upstream requirements: SRS_ModeMgm_00013 ⌈When the Alarm Clock service is present (see EcuMAlarmClockPresent ) the Ecu M Manager module shall maintain an EcuM clock whose time shall be the time in seconds since battery connect.⌋ [SWS_EcuM_04086] Upstream requirements: SRS_ModeMgm_00013 ⌈The EcuM clock shall track time in the UP and SLEEP phases.⌋ [SWS_EcuM_04087] Upstream requirements: SRS_ModeMgm_00013 ⌈Hardware permitting, the EcuM clock time shall not be reset by an ECU reset.⌋ [SWS_EcuM_04088] Upstream requirements: SRS_ModeMgm_00017 ⌈There shall be one and only one wakeup source assigned to the EcuM Clock (see EcuMAlarmWakeupSource ).⌋