Why pre-screen embedded engineers before the technical panel
The characteristic embedded problem is a device that fails once a week in a customer's building, with no debugger attached and no logs worth reading. Solving it means reasoning from the schematic, the timing and what the hardware can tell you. Engineers worth hiring have done that and can walk through one. A short screen asks for the hardest bug they found, which separates firmware experience from application code near a device.
What actually matters when screening Embedded Software Engineer candidates
- 01
Technical depth
Check depth in C on bare metal or RTOS: interrupt latency, DMA, memory maps, linker scripts, I2C/SPI/CAN drivers, and which MCU families (STM32, NXP, ESP32) they programmed.
- 02
Work that shipped
Ask for products that reached production: board bring-up, firmware versions released, OTA update mechanisms, certification runs (CE, FCC, IEC 62304) and unit volumes behind them.
- 03
Diagnosis under uncertainty
Probe how they chase intermittent faults: oscilloscope and logic analyser traces, JTAG or SWD sessions, watchdog resets, memory corruption, and bugs appearing only at temperature or on one batch.
- 04
Working across the org
Explore work with hardware, test and manufacturing: reviewing schematics before layout, negotiating pin assignments, writing production test fixtures, and handing off to QA or field support.
Pre-screening questions to ask Embedded Software Engineer candidates
12 questions grouped by what they test. Ask the same set in every screen and score answers on a consistent scale, or send them as an async video screen and compare answers side by side.
Firmware that shipped
3 questions01Can you describe embedded systems you have worked on that reached production?
Listen forDevices that shipped with volumes and their own scope, including what they still support in the field.
Prototypes and evaluation boards only, or no product that reached customers.
02Have you had exposure to firmware development?
Listen forFirmware written from bring-up onwards, with the update mechanism and its failure handling described.
Firmware experience limited to application layers, or updates with no recovery path.
03Do you have experience with safety-critical software development standards?
Listen forStandards worked under with what they actually changed in daily practice, not just named.
Standards listed with no experience of the process, or certification treated as documentation.
Constraints understood
4 questions04How well versed are you with C and C plus plus programming?
Listen forDepth on memory layout, undefined behaviour and what the compiler does at optimisation levels.
Language proficiency claimed with no awareness of undefined behaviour or alignment.
05What is your experience with real-time operating systems?
Listen forTask priorities and scheduling reasoned about, with a priority inversion or timing failure they hit.
Real-time systems used as a task library, with no reasoning about deadlines or jitter.
06Can you explain your understanding of microcontroller architecture?
Listen forPeripherals, interrupts and memory map understood well enough to write a driver from a datasheet.
Work limited to vendor libraries, or no experience reading a datasheet directly.
07Do you have experience developing driver-level software?
Listen forDrivers written against a datasheet with the hardware errata handled, and timing verified.
Drivers only configured rather than written, or errata never encountered.
Intermittent faults
3 questions08How proficient are you in debugging with hardware debuggers?
Listen forDebugger used with breakpoints, trace and register inspection, alongside a scope or analyser when needed.
Debugging done entirely with print statements, or no use of hardware instrumentation.
09Can you discuss an instance where you solved a complex issue in an embedded system?
Listen forAn intermittent fault traced to a root cause, with the reasoning that narrowed it down.
Bugs fixed by changing things until they went away, or root cause never established.
10Do you have experience with software and hardware interfacing and diagnosis?
Listen forComfort deciding whether a fault is software or hardware, with evidence used to make that call.
Hardware assumed correct by default, or faults handed straight back to the hardware team.
Working with hardware
2 questions11Have you worked with detailed design and software design documentation?
Listen forDocumentation that others used, particularly interface definitions agreed with the hardware team early.
Documentation written after the fact for a process, or interfaces agreed verbally.
12How familiar are you with digital and analogue electronics?
Listen forEnough electronics to read a schematic and question a hardware design before boards are made.
No ability to read a schematic, or hardware treated as entirely someone else's concern.
How to score responses
Score every candidate on the same four criteria immediately after the screen. At this stage you are shortlisting for panel interviews, not making the final call.
Technical depth
35%5Names specific silicon and peripherals, explains ISR design, stack sizing and register-level work without reaching for vague abstractions.
Work that shipped
30%5Points to shipped devices, describes their role from prototype through EVT/DVT/PVT, and cites field firmware versions and defect rates.
Diagnosis under uncertainty
20%5Recounts a specific hard fault, the instrumentation used, hypotheses eliminated in order, and how root cause was proven not guessed.
Working across the org
15%5Describes concrete pushback given to EE or mechanical peers, plus test jigs or bootloaders built so factory and support teams could work.
The characteristic bug fails once a week in a customer's building with no debugger attached. A one-way video screen asks for the hardest one they found.
Try it on HirevireScreening FAQ
Process basics
How long should a pre-screening round for this role take?
Fifteen minutes across eight to ten questions, answered async. Enough to establish firmware that shipped, test their command of the constraints, and hear a real debugging story.
Should I test coding skill in the screen?
No. Use the screen for shipped work, constraints and debugging judgement, then test code on hardware in the technical round where you can see how they handle a real target.
Evaluating answers
What is the strongest signal when screening this role?
The hardest bug they found. Embedded engineers with real experience describe reasoning across software and hardware. Anyone whose difficult bugs were all logic errors has not worked close to the metal.
How do I judge their constraint awareness?
Ask what they do when memory runs out. Real answers cover static allocation, stack analysis and what they cut. Anyone reaching for dynamic allocation on a small target has not been burned by it.
Go deeper on this role
Sanat has been hiring since 2012 and watching the recruitment industry change up close ever since, and turned that screening process into Hirevire's video screening platform. LinkedIn
