• Back to the original question:
    Is bitwise deletion possible?

    After studying the datasheet of the 24c32 that is coming with my RTC module the answer is: No

    It only supports byte-write or page-write meaning 32 bytes in one of the 256 pages.

    Regarding space management:
    Since it's an odometer and values should only go up, it should be quite simple.

    What about this simpler method:
    (the example shows 4 pages with 1 byte each, but can be scaled to 256 pages of 32 bytes easily)

    1. initialization: write odometer value to first page, set rest to 0: [ 1, 0, 0, 0 ]
    2. current element: is the one with the highest number (the last one written)
    3. write new value: a) find current element, move one page forward (wrap around the ends like a ring buffer), write new value to that element: [1, 2, 0, 0]

    Next iterations: [1, 2, 3, 0] [1, 2, 3, 4], [5, 2, 3, 4] etc...

    This way wear is spread across all pages evenly, there is no need of any extra space management structure.
    Since the highest value marks the current element there can be a payload with history data just after the actual odometer value:
    [ [1, p], [2, p], [3, p], ...]

    Also writing can be reduced to something like: once every N minutes or K kilometers, whichever comes first.
    If there is a power fail, only the last N minutes or K kilometers are lost.

    The datasheet for 24C32 states 1,000,000 write cycles endurance - so without any levelling and writing every minute or km that would be 1000000 km (which is more than enough) or 694 days, nearly 2 years of non-stop riding.
    Spreading this over 256 pages should multiply these values by 256 and keep me on the safe side...


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