A 'LowVoltage' event occurs on HMI when battery voltage hits below a certain predefined threshold set by the system.
In case of such event, SDL operations are halted including receiving and processing of normal RPC messages from HMI.
HMI sends system signals of the range SIGRTMIN - SIGRTMAX for LowVoltage, WakeUp and IgnitionOff to all smartDeviceLinkCore processes.
LOW_VOLTAGE signal to SDL when a 'LowVoltage' event occurs
WAKE_UP signal to SDL when the voltage recovers
IGNITION_OFF signal when SDL processes have to be terminated, applications have to be unregistered due SDL functionality suspension during a LOW VOLTAGE event
After the voltage level is restored HMI sends
WAKE_UP signal to SDL and SDL processes its regular work and all operations resumption.
WAKE_UP signal, all applications will be unregistered and the device disconnected.
LOW_VOLTAGE was received at the moment of writing to policies database, SDL and Policies Manager must keep policies database correct and working. After
WAKE_UP policy database reflects the last known correct state.
UNIX signals are used to exchange shutdown and wake-up signals between HMI and SDL Core during a 'LowVoltage' event.
UNIX signals provide ability to use signals from SIGRTMIN to SIGRTMAX for custom needs.
SDL uses this range for handling
Offset for SIGRTMIN from this notifications is defined in the 'Main' section of the smartDeviceLink.ini file:
[MAIN] LowVoltageSignal = 1 ; Offset for from SIGRTMIN WakeUpSignal = 2 ; Offset for from SIGRTMIN IgnitionOffSignal = 3 ; Offset for from SIGRTMIN