Embedded Hardware Interview Questions
Questions where hardware meets firmware: buses, GPIOs, resets, and what happens between power-on and main().
Before you start
What you should already be comfortable with:
- Flip-flops, clocks and setup/hold time
- Open-drain vs push-pull outputs
- RC time constants
- A MOSFET used as a switch; reading GPIO limits in a datasheet
What interviewers are really testing
- Treating a bus as a circuit — pull-ups, capacitance and rise time
- Driving real loads from a GPIO: flyback paths, gate drive, safe start-up states
- What happens between power-on and the first line of main()
- Reset, clock-domain crossing and metastability
- Choosing an MCU, an FPGA or an application processor — with reasons
Start with these two — free full answers
Compare I²C and SPI. When would you choose each?
Think first: Before you read on: compare the number of wires, who drives each line (open-drain or push-pull), and how one device is selected on each bus.
How do you size I²C pull-up resistors?
Think first: Before you read on: what happens to the rising edge if the resistor is too large? What happens to the low level if it is too small? Each one gives you a limit.
Study order
Work through the stages in order. ● screening · ●● onsite technical · ●●● design / senior. Pages marked "Going deeper" add explanation that is not in the book; the two marked "Free answer" show the full answer; every page tells you where the full answer is in the book.
- Buses
- EM-01 — I²C vs SPI ● Free answer
- EM-02 — Sizing I²C pull-ups ●● Free answer
- I/O and loads
- Boot, reset and timing
- EM-04 — Power-on to main(): what takes time? ●● Going deeper
- EM-05 — Reset pin design ●● Going deeper
- EM-06 — Metastability ●●
- System choices
Related questions in other chapters
- PW-16 — Power sequencing ●●
- DC-03 — Sample-and-hold vs setup-and-hold ●
- HS-09 — SPMI vs I²C ●●
- MD-06 — Bringing up a new board ●●
The book
The book has all 12 questions in this chapter with the full answer: how to explain it on a whiteboard, the numbers worth quoting, and the follow-ups that come next.
More topics
PCB Design Interview Questions · Power Electronics Interview Questions · Signal Integrity Interview Questions · Analog & Op-Amp Interview Questions · Power Integrity Interview Questions