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Embedded C Online Test

About the test:

The Embedded C Test uses scenario-based MCQ questions to evaluate a candidate's ability to develop C/Embedded C drivers/ libraries and coding questions to evaluate hands-on C programming skills. The code-tracing MCQ questions evaluate Embedded C fundamentals (data types, variables, pointers), I/O Hardware Addressing, fixed-point arithmetic operations, accessing address spaces, Preprocessor directives and efficient application of object-oriented programming principles to firmware development.

Covered skills:

  • C basics (variables; data types; declarations; functions)
  • Pointers (with Arrays; Structures; Unions)
  • Embedded C basics (registers; directives; drivers)
  • Bit Operations (Packaging data; unpacking data; bit manipulations)
See all covered skills

9 reasons why
9 reasons why

Adaface Embedded C Online Test is the most accurate way to shortlist Embedded Electronics Engineers



Reason #1

Tests for on-the-job skills

The Embedded C online assessment test reduces the administrative overhead of interviewing too many candidates and saves expensive engineering time by filtering out unqualified candidates.

The Adaface Embedded C test screen candidates for the typical skills recruiters look for in an Embedded software developer:

  • Expertise in writing Embedded C code for optimized I/O performance
  • Solid understanding of data structures, machine level language, assembly language, and electronic programmable device architecture
  • Familiarity with microcontrollers and embedded processors
  • C basics (Data types, variables definitions, storage class specifiers)
  • Bit manipulation techniques using bit-wise operators
  • Working with structures, bitfields, unions, bit extraction and memory-mapped peripheral registers
  • Pointers arithmetic and importance of pointer datatypes
  • Interpreting and using complex variable definitions involving a combination of const pointers, const data, volatile const, pointer and non-pointer variables
  • Creating registers from the address
  • Defining Peripheral address
  • Implicit and explicit casting
  • Importance of volatile during compiler optimization
  • Packing and unpacking of data for transmission and storage
  • Aligned and unaligned data access on structures
  • Use the debugger effectively to analyze and resolve bugs

Additionally the test has coding questions to evaluate hands-on C programming skills.

Reason #2

No trick questions

Traditional assessment tools use trick questions and puzzles for the screening, which creates a lot of frustration among candidates about having to go through irrelevant screening assessments.

The main reason we started Adaface is that traditional pre-employment assessment platforms are not a fair way for companies to evaluate candidates. At Adaface, our mission is to help companies find great candidates by assessing on-the-job skills required for a role.

Why we started Adaface ->
Reason #3

Non-googleable questions

We have a very high focus on the quality of questions that test for on-the-job skills. Every question is non-googleable and we have a very high bar for the level of subject matter experts we onboard to create these questions. We have crawlers to check if any of the questions are leaked online. If/ when a question gets leaked, we get an alert. We change the question for you & let you know.

These are just a small sample from our library of 10,000+ questions. The actual questions on this Embedded C Test will be non-googleable.

🧐 Question

Medium

Logic Black Box
Solve
Consider the following logic box. There are three inputs A, B, C and three outputs not A, not B and not C (not A = !A, not B = !B, not C = !C).

Is it possible to achieve the expected outputs from the inputs using:

- Only AND and OR gates
- Just two (2) NOT gates
- No NAND, NOR, XOR, or XNOR gates
 image

Medium

Memory Map
Memory Architecture
Solve
Review the following Embedded Systems code and memory map of 16-bit microcontroller:
 image
 image
Here are the specifications of the microcontroller:

- The stack grows from area D, whereas the program and static variables are stored in area C
- ‘int’ in the system is a 16-bit number
- There is no operating system and no memory protection
- The program is compiled and loaded into area C
Pick the correct statements:

A: first_var, second_var and input will be in area D
B: first_var and second_var will be in area C, input will be in area D
C: If the contents of 0x0010 at the start of the program is 7, the program will print 0 and exit
D: If the contents of 0x0010 at the start of the program is 42, the program will print 0 and exit
E: If the contents of 0x0010 at the start of the program is 42, the program will overflow the stack overwriting the program and static variables region
F: If the program overflows and overwrites the program and static variables region, arbitrary data is executed as if it is the program, causing unpredictable results

Medium

Multi-tasking
Multi-tasking
Solve
Review the following Embedded Systems code:
 image
Here’s the specification for the program:
- first_var and second_var are global variables shared among several threads
- first_lock and second_lock are mutex locks that protect access to first_var and second_var
- Reads and writes to variables first_var and second_var are not guaranteed to be atomic
- No locks must be acquired unnecessarily
- Acquire second_var lock first before acquiring first_var lock by any thread that is going to use both first_var and second_var
Assume that if a thread attempts to acquire a lock it already holds, then it is immediately granted the lock. Pick the correct statements:

A: The provided code does not meet the specification completely since second_lock is not acquired before acquiring first_lock for procedure 'foo'

B: Replacing foo with logic of foo1 makes sure locks are not acquired unnecessarily and  second_lock is acquired before acquiring first_lock

C: Replacing foo with logic of foo1 makes sure second_lock is acquired before acquiring first_lock but there are cases when second_lock is acquired unnecessarily (when first_var < input)

D: Replacing foo with logic of foo2 makes sure locks are not acquired unnecessarily

E: Replacing foo with logic of foo2 is optimized version of foo1 but there are cases when second_lock is still acquired unnecessarily (when first_var value changes from the time ‘res’ value is computed and by the first_lock is acquired again.

Medium

Strings
Strings
Solve
What is the output of the following C code?
 image

Medium

Memory Allocation
Solve
Check the following three C functions:
 image
Which among these will likely cause issues with pointers?

Medium

Pointers and Structs
Solve
What is the output of the following C code?
 image

Easy

Registration Queue
Logic
Solve
We want to register students for the next semester. All students have a receipt which shows the amount pending for the previous semester. A positive amount (or zero) represents that the student has paid extra fees, and a negative amount represents that they have pending fees to be paid. The students are in a queue for the registration. We want to arrange the students in a way such that the students who have a positive amount on the receipt get registered first as compared to the students who have a negative amount. We are given a queue in the form of an array containing the pending amount.
For example, if the initial queue is [20, 70, -40, 30, -10], then the final queue will be [20, 70, 30, -40, -10]. Note that the sequence of students should not be changed while arranging them unless required to meet the condition.
⚠️⚠️⚠️ Note:
- The first line of the input is the length of the array. The second line contains all the elements of the array.
- The input is already parsed into an array of "strings" and passed to a function. You will need to convert string to integer/number type inside the function.
- You need to "print" the final result (not return it) to pass the test cases.

For the example discussed above, the input will be:
5
20 70 -40 30 -10

Your code needs to print the following to the standard output:
20 70 30 -40 -10

Medium

Longest Road
logic
hashmaps
Solve
A startup company E-Motors is building driverless automated cars. The car contains a sensor that checks the road quality for the next N meters to decide the optimal speed at which the cars should move. We are given recorded data by the sensor in the form of an array, where each element of the array is the rating given to 1 meter of the road in sequence. 

The rating given by the sensor is from 1 to 100, where 100 represents the road with the best condition, and any rating above 60 is optimal. Find the longest stretch of road in meters that is categorized as optimal by the sensor.

The input is an array of "strings" which needs to be converted from string to integer/number inside the function.

Medium

Visitors Count
Strings
Solve
A manager hires a staff member to keep a record of the number of men, women, and children visiting the museum daily. The staff will note W if any women visit, M for men, and C for children. You need to write code that takes the string that represents the visits and prints the count of men, woman and children. The sequencing should be in decreasing order. 
Example:

Input:
WWMMWWCCC

Expected Output: 
4W3C2M

Explanation: 
‘W’ has the highest count, then ‘C’, then ‘M’. 
⚠️⚠️⚠️ Note:
- The input is already parsed and passed to a function.
- You need to "print" the final result (not return it) to pass the test cases.
- If the input is- “MMW”, then the expected output is "2M1W" since there is no ‘C’.
- If any of them have the same count, the output should follow this order - M, W, C.
🧐 Question🔧 Skill

Medium

Logic Black Box
3 mins
Embedded Systems
Solve

Medium

Memory Map
Memory Architecture
3 mins
Embedded Systems
Solve

Medium

Multi-tasking
Multi-tasking
2 mins
Embedded Systems
Solve

Medium

Strings
Strings
2 mins
C
Solve

Medium

Memory Allocation
2 mins
C
Solve

Medium

Pointers and Structs
2 mins
C
Solve

Easy

Registration Queue
Logic
30 mins
Coding
Solve

Medium

Longest Road
logic
hashmaps
25 mins
Coding
Solve

Medium

Visitors Count
Strings
30 mins
Coding
Solve
🧐 Question🔧 Skill💪 Difficulty⌛ Time
Logic Black Box
Embedded Systems
Medium3 mins
Solve
Memory Map
Memory Architecture
Embedded Systems
Medium3 mins
Solve
Multi-tasking
Multi-tasking
Embedded Systems
Medium2 mins
Solve
Strings
Strings
C
Medium2 mins
Solve
Memory Allocation
C
Medium2 mins
Solve
Pointers and Structs
C
Medium2 mins
Solve
Registration Queue
Logic
Coding
Easy30 minsSolve
Longest Road
logic
hashmaps
Coding
Medium25 minsSolve
Visitors Count
Strings
Coding
Medium30 minsSolve
Reason #4

1200+ customers in 75 countries

Brandon

With Adaface, we were able to optimise our initial screening process by upwards of 75%, freeing up precious time for both hiring managers and our talent acquisition team alike!


Brandon Lee, Head of People, Love, Bonito

Reason #5

Designed for elimination, not selection

The most important thing while implementing the pre-employment Embedded C Test in your hiring process is that it is an elimination tool, not a selection tool. In other words: you want to use the test to eliminate the candidates who do poorly on the test, not to select the candidates who come out at the top. While they are super valuable, pre-employment tests do not paint the entire picture of a candidate’s abilities, knowledge, and motivations. Multiple easy questions are more predictive of a candidate's ability than fewer hard questions. Harder questions are often "trick" based questions, which do not provide any meaningful signal about the candidate's skillset.

Reason #6

1 click candidate invites

Email invites: You can send candidates an email invite to the Embedded C Test from your dashboard by entering their email address.

Public link: You can create a public link for each test that you can share with candidates.

API or integrations: You can invite candidates directly from your ATS by using our pre-built integrations with popular ATS systems or building a custom integration with your in-house ATS.

Reason #7

Detailed scorecards & comparative results

Reason #8

High completion rate

Adaface tests are conversational, low-stress, and take just 25-40 mins to complete.

This is why Adaface has the highest test-completion rate (86%), which is more than 2x better than traditional assessments.

Reason #9

Advanced Proctoring


What questions are included for Senior Embedded C engineers?

The questions for Senior candidates are based on advanced Embedded C topics like:

  • Importance of structures in peripheral register access
  • Experience with Standard C and Embedded C libraries
  • Develop embedded drivers from scratch using information from the datasheet (GPIO drivers, TIMERS drivers, UART drivers)
  • Ability to work without third-party libraries or header files
  • Analyzing the chip documentation
  • De-coupling of I/O from real-time processing to avoid response time over-runs
  • Real-time system design concepts, decomposition of functions, and identification of key services
  • Structured interrupt handling

Additionally, the coding question will be of higher difficulty level compared to junior Embedded C tests.

What roles can I use the Embedded C Test for?

  • Embedded Electronics Engineer
  • Embedded Software Engineers C
  • Embedded C Engineers
  • Firmware Engineers - Embedded C
  • Electronic & Electrical Engineers
  • Software Testing Specialists - Microcontrollers
  • Senior Embedded C Engineers

What topics are covered in the Embedded C Online Test?

Data types
Number Systems (Hex, Decimal and Binary)
Variables
Declarations
Operators
Functions
Friends
Pointers
Union
Enum
Arrays (with pointers)
Structures (with pointers)
Casting
Registers
Unions
Bit-fields
Qualifiers
Const and volatile
MCU peripheral registers
Number Systems (Hex, Decimal and Binary)
Storage Classes
Header Files
Preprocessors
Conditional Compilation
Macros
Linker and locator
Testing & Validation
I/O performance
Interrupts
Singapore government logo

The hiring managers felt that through the technical questions that they asked during the panel interviews, they were able to tell which candidates had better scores, and differentiated with those who did not score as well. They are highly satisfied with the quality of candidates shortlisted with the Adaface screening.


85%
reduction in screening time

Embedded C Online Test FAQs

Can I evaluate C coding skills and Embedded C skills in the same test?

Yes. You can review our standard C online test to get a sense of what kind of questions will be used to evaluate C. The final test will have MCQ questions to evaluate C, Embedded C and coding questions to evaluate C coding skills.

Can I evaluate C++ and Embedded C in the same test?

Yes. You can review our standard C++ online test to get a sense of what kind of questions will be used to evaluate C++. The final test will have MCQ questions to evaluate C++, Embedded C and coding questions to evaluate C/C++ coding skills.

Can I combine multiple skills into one custom assessment?

Yes, absolutely. Custom assessments are set up based on your job description, and will include questions on all must-have skills you specify.

Do you have any anti-cheating or proctoring features in place?

We have the following anti-cheating features in place:

  • Non-googleable questions
  • IP proctoring
  • Web proctoring
  • Webcam proctoring
  • Plagiarism detection
  • Secure browser

Read more about the proctoring features.

How do I interpret test scores?

The primary thing to keep in mind is that an assessment is an elimination tool, not a selection tool. A skills assessment is optimized to help you eliminate candidates who are not technically qualified for the role, it is not optimized to help you find the best candidate for the role. So the ideal way to use an assessment is to decide a threshold score (typically 55%, we help you benchmark) and invite all candidates who score above the threshold for the next rounds of interview.

What experience level can I use this test for?

Each Adaface assessment is customized to your job description/ ideal candidate persona (our subject matter experts will pick the right questions for your assessment from our library of 10000+ questions). This assessment can be customized for any experience level.

Does every candidate get the same questions?

Yes, it makes it much easier for you to compare candidates. Options for MCQ questions and the order of questions are randomized. We have anti-cheating/ proctoring features in place. In our enterprise plan, we also have the option to create multiple versions of the same assessment with questions of similar difficulty levels.

I'm a candidate. Can I try a practice test?

No. Unfortunately, we do not support practice tests at the moment. However, you can use our sample questions for practice.

What is the cost of using this test?

You can check out our pricing plans.

Can I get a free trial?

Yes, you can sign up for free and preview this test.

I just moved to a paid plan. How can I request a custom assessment?

Here is a quick guide on how to request a custom assessment on Adaface.

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