Firmware Engineer Interview Questions | Glassdoor

Firmware Engineer Interview Questions

376

Firmware engineer interview questions shared by candidates

Top Interview Questions

Sort: RelevancePopular Date

DSP Firmware Engineer at Qualcomm was asked...

Jul 15, 2010

Mar 16, 2010
 How to swap the values in 2 variables without using a temporary variable.5 Answersa=a^b b=b^a a=a^bbut it should say swap two integers! because this XOR won't work with float for exampleThis works for floats: a = a+b b = a-b a = a-b But you might overflow on a+b.Show More Responsespush and pop the values from the stack.While using the XOR method, add condition to check if numbers are same. If they are same, XOR results in 0.

Senior Firmware Engineer at Synaptics was asked...

Nov 11, 2009
 How to invert all the bits in a byte? e.g. 0x55 should be changed to 0xAA.3 AnswersTake 1's complement using ~But how do you implement ~?mask=0xffffffff; no^=mask;

Firmware Engineer at Qualcomm was asked...

May 7, 2011
 Puzzles 1: You have rope that take 60 min to burn. Speed of burning is not uniform. Example: it doesn't take 30 min to burn half Using two ropes, how would you get 45 min? Answer: First Rope. Burn both ends at same time Second Rope: Burn only one side. when First rope is totally burn, it's been 30 min, now burn the rest of second rope both ends. Which should take additional 15 min. 30 + 15 = 45 min. Puzzle 2: There is a guy in a boat holding a rope that's tight to a Top of pole in the shore. He keep pulling the rope until he reach the shore. What is the speed relationship between amount of rope he pulls, vs horizonal speed? Which speed is higher? Answer: Horizonal speed is faster than the amount of rope he pulls. (Horizonal distance he travel is higher than amount of rope he pulls, by triangle theory where sum of two sides must be greater than 3rd side) Puzzle 3: in Analog Clock, It's exacly 3:00 Clock. What time would the Hour hand, and Min hand would overlap each other? 4 Answersfor Puzzle 3: It's 6:30The analog and min hand overlap once each hour so the next overlap after 3:00 would be 3:16 and some change. Sanity check: 16 minutes should be between the 3:00 and 4:00 on the clock, which is true. Math: Hour hand gets an equation like 3 + (1/60)*minutes, since the hour hand starts at 3 and every minute it increases by 1/60th of an hour. The minute hand gets 12*(1/60) * minutes since in 60 minutes it goes around the 12 hours of the clock. So 3+(1/60)x = (12/60)x gives you 180/11 or about 16.1) hour = min / 12 deg 2) min = hour + hour(initial) = hour + 90 deg 1=>2 and solving gives 98.18 deg. Converting back into time format gives 3:16:22.Show More Responsesyou should keep the same units: Hour hand: starts at 15 min so 15 min + 5 min/hr*t Min hand: 60 min/hr 15 min + 5 min/hr * t = 60 min/hr 15 min = 55 min/hr * t 15/55 = .2727 hr .2727 hr * 60 min/hr = 16.3636 min = 16 min 21.8182 sec

Firmware Engineer at Qualcomm was asked...

Mar 1, 2012
 Name a few different types of registers.2 AnswersShift, etcDepends on the architecture. In some processors, addressing is done using Address regs and modifier regs. And then there are shadow registers, which avoid the need for context saves.

Senior Firmware Engineer at Hospira was asked...

Mar 3, 2015
 Technical C programming and logic questions.1 AnswerVerbal or on white board.

DSP Firmware Engineer (Wireless Modem) at Qualcomm was asked...

Jan 6, 2010
 Swap two numbers without using a temporary variable3 Answersx = 10 y = 5 x = x+y // x = 15, y =5 y = x-y // x = 15 , y = 10 x = x-y // x = 15 - 10 = 5 , y = 10 another way, x = x^y y = x^y x = x^yShift register.a = a ^ b; b = a ^ b; a = a ^ b;

Firmware Engineer at NetApp was asked...

Apr 8, 2019
 Pointers, TCP and UDP, debugging, past projects1 AnswerPointer question was a programming question (It was for checking my knowledge with pointers ), Difference between TCP and UDP - told about reliable and non reliable applications (keeping time a factor), debugging in Linux (gdb).

Senior Firmware Engineer at Bigfoot Biomedical was asked...

Apr 5, 2019
 What are some of the python libraries you have used1 AnswerMatplotlib

DSP Firmware Engineer at Qualcomm was asked...

Apr 14, 2010
 How to estimate the DP SNR? 1 AnswerBased on the DP bit and pilot channel noise estimation and weighted to the SNR.
110 of 376 Interview Questions