Simple whiteboard questions for embedded systems students
October 28, 2024 7:00 AM Subscribe
I’m doing practice interviews for a bunch of of junior and senior college Embedded Systems majors. I’ve got the non-visual questions covered, but I’m looking for a collection of whiteboard exercises where they draw me a system.
In a practice practice interview I asked one of them to draw me the embedded system section of a vending machine, using an Arduino as the core. He ended up drawing a flow chart of the machine operation, and then we looked at each step and identified what part of the hardware it would require. That was a pretty good answer.
In a practice practice interview I asked one of them to draw me the embedded system section of a vending machine, using an Arduino as the core. He ended up drawing a flow chart of the machine operation, and then we looked at each step and identified what part of the hardware it would require. That was a pretty good answer.
Draw? I always asked my comms lab students to draw and then explain the dmx waveform, I knew it was a common exam question and if they couldn't do it I don't know how they expected to know they'd found one on a scope.
I think being able to articulate how a serial bus works with figures is a great demonstrator of knowledge.
posted by adventureloop at 7:53 AM on October 28
I think being able to articulate how a serial bus works with figures is a great demonstrator of knowledge.
posted by adventureloop at 7:53 AM on October 28
Draw a typical interface between a microcontroller and a peripheral chip, or multiple chips. Do UART, I2C, and SPI.
UART - you should see the TX/RX pair, and hopefully they remember to swap lines between units.
I2C - you should see SCK/SDA run to every chip. Ask how a chip knows when to respond. If you want to get fancy ask about 7-bit addressing. Really fancy? Ask them to add the pull-up resistors.
SPI - Individual CS lines to every part, MOSI/MISO connected to all of them. Then ask them to chain multiple SPI listeners on a single port and CS line.
These three busses will be 95% of the work an early embedded systems developer will touch. If they can't explain these in somewhat useful detail with some mid-level range of accuracy that's a red flag in an interview for me.
posted by JoeZydeco at 8:12 AM on October 28
UART - you should see the TX/RX pair, and hopefully they remember to swap lines between units.
I2C - you should see SCK/SDA run to every chip. Ask how a chip knows when to respond. If you want to get fancy ask about 7-bit addressing. Really fancy? Ask them to add the pull-up resistors.
SPI - Individual CS lines to every part, MOSI/MISO connected to all of them. Then ask them to chain multiple SPI listeners on a single port and CS line.
These three busses will be 95% of the work an early embedded systems developer will touch. If they can't explain these in somewhat useful detail with some mid-level range of accuracy that's a red flag in an interview for me.
posted by JoeZydeco at 8:12 AM on October 28
Response by poster: Draw?
None of these students speak English as a first language, so I’m encouraging them to be as visual as possible so people don’t judge their intelligence on their accent.
posted by Tell Me No Lies at 9:44 AM on October 28 [2 favorites]
None of these students speak English as a first language, so I’m encouraging them to be as visual as possible so people don’t judge their intelligence on their accent.
posted by Tell Me No Lies at 9:44 AM on October 28 [2 favorites]
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It worked well - it's a superficially simple problem but has some complexities.
posted by Hatashran at 7:05 AM on October 28