OTA chunk writer

The code

Embedded C for Cortex-M. It compiles. There are 3 real bugs in it: the kind that pass a bench test and fail in the field.

#define SLOT_ADDR  0x08020000u
#define SECTOR     4096u

bool ota_chunk(uint32_t offset, const uint8_t *data, uint32_t len, bool last)
{
    uint32_t addr = SLOT_ADDR + offset;
    if (offset % SECTOR == 0) {
        flash_erase_sector(addr);
    }
    flash_program(addr, data, len);
    if (last) {
        ota_mark_pending();
    }
    return true;
}

What an interviewer expects

• Point to each line you'd stop in a code review.
• Say what actually breaks: the failure mode, not just the rule it violates.
• Fix it, then defend the fix when asked the follow-up.

The bugs, reference fixes and the follow-up question are in the practice app, after you've tried it.

Companies that test this

Matched on the skills each company's embedded roles emphasise.

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