Common embedded bugs and fixes in Embedded C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a common cause of a 'watchdog timer reset' in embedded systems?

A watchdog timer reset often happens when the system gets stuck in an infinite loop or deadlock and fails to reset the watchdog timer in time.

beginner

Why can uninitialized variables cause bugs in embedded C programs?

Uninitialized variables contain random data, which can cause unpredictable behavior or crashes when used before being set.

intermediate

How can stack overflow occur in embedded systems?

Stack overflow happens when too much memory is used on the stack, often due to deep or infinite recursion or large local variables.

intermediate

What is a common fix for race conditions in embedded systems?

Use synchronization methods like disabling interrupts or using mutexes to protect shared resources and prevent race conditions.

beginner

Why is it important to check return values of hardware access functions?

Checking return values helps detect hardware errors early and prevents the program from continuing with invalid data or states.

What is a typical symptom of a stack overflow in an embedded system?

A System crashes or behaves unpredictably

B Faster program execution

C Increased battery life

D Improved memory usage

Stack overflow causes memory corruption leading to crashes or unpredictable behavior.

Which of the following can help prevent race conditions?

A Disabling interrupts during critical sections

B Ignoring shared variables

C Using global variables without protection

D Increasing clock speed

Disabling interrupts during critical code sections prevents concurrent access and race conditions.

Why should you initialize variables before use in embedded C?

A To save memory

B To avoid unpredictable behavior from garbage values

C To make the program run slower

D To increase code size

Uninitialized variables hold random data that can cause bugs or crashes.

What does a watchdog timer do in embedded systems?

A Increases CPU speed

B Monitors battery level

C Saves power

D Resets the system if it becomes unresponsive

A watchdog timer resets the system if it stops responding to prevent hangs.

What is a good practice when accessing hardware registers?

A Use random values

B Ignore errors and continue

C Check return values for errors

D Access registers without delay

Checking return values helps detect hardware faults early.

Describe three common bugs in embedded C programming and how to fix them.

Think about memory issues, concurrency, and variable initialization.

Explain why watchdog timers are used and what causes them to reset the system.

Consider system hangs and how watchdogs help recover.