Watchdog reset recovery in Embedded C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a watchdog timer in embedded systems?

A watchdog timer is a hardware timer that resets the system if the software becomes unresponsive or stuck, helping to recover from errors automatically.

beginner

How does a watchdog reset recovery work?

When the watchdog timer expires because the software did not reset it in time, it triggers a system reset. After reset, the system can detect the cause and perform recovery steps.

intermediate

What is a common method to detect a watchdog reset after system restart?

Check a special hardware register or flag that indicates the reset source was the watchdog timer, allowing the program to know it recovered from a watchdog reset.

beginner

Why should the watchdog timer be regularly reset in the main program?

To prevent the watchdog from resetting the system during normal operation, the program must reset the watchdog timer regularly, showing it is running correctly.

intermediate

What is a safe practice when recovering from a watchdog reset?

Perform minimal initialization, log the reset cause if possible, and avoid complex operations that might cause another reset immediately.

What triggers a watchdog reset in an embedded system?

A Software fails to reset the watchdog timer in time

B User presses a reset button

C Power supply is disconnected

D Program completes successfully

The watchdog reset happens when the software does not reset the watchdog timer before it expires.

How can a program detect that a reset was caused by the watchdog?

A By checking the system clock

B By reading a file from disk

C By asking the user

D By checking a hardware reset flag or register

Most microcontrollers have a register or flag that indicates the reset source, including watchdog resets.

What should the program do regularly to avoid a watchdog reset?

A Turn off the watchdog

B Reset the watchdog timer

C Increase the watchdog timeout

D Ignore the watchdog

Resetting the watchdog timer regularly tells it the program is running fine and prevents reset.

What is a good practice after recovering from a watchdog reset?

A Disable the watchdog permanently

B Immediately restart the watchdog timer without checks

C Perform minimal initialization and log the reset cause

D Ignore the reset cause and continue normally

Minimal initialization and logging help avoid repeated resets and aid debugging.

Why is a watchdog timer useful in embedded systems?

A It helps recover from software hangs automatically

B It speeds up the processor

C It saves power

D It stores data permanently

The watchdog timer resets the system if software hangs, improving reliability.

Explain how a watchdog timer helps in system reliability and what steps you take after a watchdog reset.

Think about how the watchdog protects the system and what you do when it triggers a reset.

Describe how you would implement watchdog reset recovery in an embedded C program.

Consider initialization, normal operation, and recovery after reset.