## Problem You are implementing a software UART (Universal Asynchronous Receiver-Transmitter) receiver in C. Given a stream of raw bit samples (sampled at 8x the baud rate), decode the data bytes. A UART frame consists of: 1 start bit (0), 8 data bits (LSB first), 1 stop bit (1). Framing errors should be flagged. ```c typedef struct { uint8_t data; bool framing_error; } UartFrame; int uart_decode(const uint8_t* samples, int n_samples, UartFrame* out_frames, int max_frames); // Returns number of frames decoded ``` **Example:** ``` // Baud rate = 9600, sample rate = 76800 (8x oversampling) // Bit 0 sampled at positions 4,12,20,28... (center of each bit window) // Frame for byte 0xA5 (10100101): // START=0, bits=1,0,1,0,0,1,0,1, STOP=1 // -> {data=0xA5, framing_error=false} ``` ## Follow-ups 1. Why do you sample at the center of the bit window rather than the edge, and how does oversampling reduce bit-error rate? 2. How do you detect and recover from framing errors (missing stop bit) without losing subsequent frames? 3. What changes if you add parity support (even/odd parity bits)? 4. How would you implement the transmit (TX) side to produce the same bit stream at a target baud rate?

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UART Handler: Implement a Software UART Receiver That Decodes Serial Frames

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Problem You are implementing a software UART (Universal Asynchronous Receiver-Transmitter) receiver in C. Given a stream of raw bit samples (sampled at 8x the baud rate), decode the data bytes. A UART frame consists of: 1 start bit (0), 8 data bits (LSB first), 1 stop bit (1). Framing errors should be flagged. Example: Follow-ups Why do you sample at the center of the bit window rather than the edge, and how does oversampling reduce bit-error rate? How do you detect and recover from framing erro…

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This is a candidate experience report from a applied intuition interview during the phone round.

It covers the following topics: Coding, Embedded, Phone .

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UART Handler: Implement a Software UART Receiver That Decodes Serial Frames

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