Espressif Embedded Software Developer interview questions

First interview: 1) First repeating character in a string with O(N) 2) Check whether the given number is even with O(1) & without the modulo operator 3) Check whether the given number is power of 2 with O(1), 4) The 2 eggs and 10 floors problem. 5) Questions about I2S protocol, I2C vs SPI, design considerations for a PCB layout.

Round 1: 1. Few questions related to BLE Mesh fundamentals: Type of bearers, What is Friend Node, Foundation Model, BLE Mesh Layers. 2. Few questions related to BLE: Content of advertisement data and its Max Size, How to send more that Max_Size in advertising 3. C programming a. Define link list node b. Size of link list node with data type as int and char. [ focuse was on alignment, padding, and packed attribute ] c. Write code to add note in link list d. Function prototype of `memcpy` and write code for `memcpy` e. How to avoid void pointer ++ operation f. How assign more than one byte g. Constrains using int pointer h. When copying data what if source and dest addresses are overlapping 4. Data structure and Algorithms a. Write code for whether number is power of 2 b. n + 1 elements in array(1 to n), one of the number if repeated, find it c. n: elements, every number is repeated except one, find that d. How to find the center of link list 5. OS fundamentals and System Design a. Design system for smart light which is controlled by WAN, LAN and Physical button Round 2: 1. How to sort an array of roll numbers, starts with 1, no holes no repetition. Expected time complexity O(n). 2. Puzzele: In a gaint wheel, man at position 6 O-clock is continuously firing, who all will be killed? Round 3: 1. Two threads with infinite while loop, both have different volatile variable, one thread increments, another decrements. What happens in this case? 2. Implement Priority Queue