Automotive AUTOSAR watchdog and supervisions in details

Explore how the watchdog timer detects software anomalies and hardware malfunctions in embedded systems and resets the microprocessor to maintain reliability.

Explore watchdog timer types, windowed vs non windowed, and how open and closed refresh windows prevent ECU resets, with automotive external watchdog and bootloader boot time considerations.

Explore Autosar watchdog architecture with three layers—the service layer with watchdog manager, the abstraction layer with the watchdog interface, and nickel layer; the manager provides alive, deadline, and logical supervision.

Learn how the automotive Autosar watchdog manager uses alive, deadline, and logical supervision, configured through local and global state machines that align, to trigger safe states and hardware resets.

Explore alive supervision parameters, including supervised entity periodicity, watchdog main function periodicity, reference cycle, alive indications, margins, and failure tolerance driving the state machine.

Explore alive supervision in Autosar by examining a ten-millisecond runnable, checkpoint reached counters, and how the watchdog main validates reference cycles with margins that trigger resets.

Explore deadline supervision in Autosar, defining timing constraints between start and end checkpoints with minimum and maximum time, including infinite maximums and multiple transitions.

Explore the logical supervision technique for embedded systems, focusing on control flow errors and verification via a graph of checkpoints and transitions in the watchdog manager.

Compare internal and external logical supervision in AUTOSAR watchdogs, detailing mode independent internal transitions within a supervision entity and mode dependent external transitions between entities, and how checkpoints validate sequences.

Explore the local supervision status state machine in the watchdog manager, showing how per-entity states (okay, expired, failed, deactivated) depend on alive, deadline, and logical supervision and a failure tolerance.

Coordinate the global watchdog supervision by aggregating local statuses into a single global state machine, managing deactivation, expired and stopped transitions with configurable expired supervision tolerance.

Explore the watchdog interface between the manager and driver, detailing mode type, set mode, get mode, and set trigger condition, including off, slow, fast timeouts and zero timeout immediate stop.

Explore the watchdog driver parameters for a windowed watchdog, including sync time, closed and open windows, and the refresh window, with refreshment types like rising and falling edges and pulses.

Select Autosar watchdog parameters by using minimum sync time and open window, maximum closed window, and a typical pulse width.

Explore a real Texas Instruments TLINx44x watchdog example in pin mode, showing edge-triggered refresh and 50/50 open and closed windows with safe 9 ms open and 22 ms closed timing.

Design external watchdogs for automotive software, addressing soft reset and programming sessions, and fix timing by syncing refreshment with boot manager or opting for a hard reset.

Measure and verify the watchdog design with an oscilloscope, ensuring refreshes occur in the middle of the open window and the first refresh precedes the sync timeout.

Learn Autosar watchdog concepts, including external and internal watchdogs, windowed modes, and alive, deadline, and logical supervision, plus layers, interfaces, and state machines.