Tork Motors Embedded Systems Engineer Interview: Rounds, Questions and Preparation

What the job involves

As an Embedded Systems Engineer in the EV and cleantech sector, you will develop firmware for battery management systems (BMS), motor controllers, and vehicle control units. Day to day work includes writing C code for microcontrollers, debugging communication protocols like CAN, and ensuring real-time performance and safety. You will also collaborate with hardware and testing teams to validate software on test benches and vehicles.

Role and Technical Knowledge

1. 1

   Explain the difference between a microcontroller and a microprocessor. Which one would you use for a battery management system and why?

   Highlight that microcontrollers have integrated peripherals and are suited for real-time control, while microprocessors need external components. For BMS, a microcontroller is preferred for its low power and dedicated peripherals like ADC and CAN.

2. 2

   What is the CAN protocol? How is it used in electric vehicles?

   Describe CAN as a multi-master serial bus with message-based communication, widely used in EVs for connecting ECUs like BMS, motor controller, and dashboard. Mention arbitration, message IDs, and data frames.

3. 3

   How would you implement a simple state machine for a motor controller in embedded C?

   Explain states like idle, running, fault, and transitions based on inputs. Use a switch-case or function pointer approach, and emphasize debouncing and safety checks.

4. 4

   What is the role of a watchdog timer in an embedded system? How would you use it in a vehicle control unit?

   Watchdog resets the system if software hangs. In VCU, it ensures fail-safe operation by resetting the controller if the main loop doesn't kick the watchdog periodically.

Practical Scenarios

1. 5

   Your BMS firmware is reporting incorrect State of Charge (SOC). How would you debug this?

   Outline a systematic approach: check sensor calibration, verify voltage and current measurements, review SOC algorithm (e.g., coulomb counting), and use logging to compare with a known good reference.

2. 6

   You need to add a new sensor to an existing EV controller that communicates over I2C. What steps would you take?

   Cover hardware interfacing (pull-up resistors, addressing), writing or modifying driver code, integrating into the main loop, and testing with a logic analyzer to ensure proper communication.

3. 7

   How would you ensure your embedded software meets real-time deadlines in a motor control application?

   Discuss using an RTOS with priority-based scheduling, minimizing interrupt latency, and profiling worst-case execution time. Mention techniques like direct register access and DMA.

4. 8

   Describe a time you had to optimize code for memory or speed constraints. What did you do?

   Share a specific project example: using bit-fields, avoiding dynamic memory, optimizing loops, or using lookup tables. Quantify improvements if possible.

Behavioral and HR

1. 9

   Why do you want to work in the EV and cleantech sector, specifically at a company like Tork Motors?

   Show passion for sustainable mobility, mention specific EV technologies you find exciting, and align with the company's mission. Avoid generic answers; research the company's products.

2. 10

   Tell me about a time you worked in a team to solve a technical problem. What was your role?

   Use STAR method: describe the situation, task, action, and result. Emphasize collaboration, communication, and your contribution to the solution.

3. 11

   How do you handle tight deadlines or pressure during debugging?

   Demonstrate calm problem-solving, prioritization, and use of tools like breakpoints and logs. Mention asking for help when needed and learning from mistakes.

4. 12

   Where do you see yourself in 3-5 years in the EV industry?

   Show ambition to grow into a senior embedded engineer or technical lead, contributing to advanced EV technologies. Align with the company's growth path.

Coding and Problem Solving

1. 13

   Write a C function to reverse the bits of a 32-bit integer.

   Use bitwise operations: loop through bits, shift and OR. Show understanding of masks and efficiency. Mention lookup table for optimization.

2. 14

   Given an array of sensor readings, write code to find the maximum and minimum values without using library functions.

   Iterate through the array, update max and min. Handle edge cases like empty array. Emphasize clean, efficient code.

3. 15

   Explain how you would implement a circular buffer for UART receive data in embedded C.

   Describe head and tail pointers, overflow handling, and thread safety if using interrupts. Provide code outline or pseudo-code.

4. 16

   What are volatile and const keywords in C? Give an example of their use in embedded systems.

   volatile prevents compiler optimization for variables that can change unexpectedly (e.g., hardware registers). const makes variables read-only. Provide examples like a status register.