SSCMEx.Tick (sscmex v0.4.0)

Same-clock helpers for SSCMEx.Image.timestamp.

SSCMEx.Image.timestamp is set inside the NIF from clock_gettime(CLOCK_MONOTONIC) in nanoseconds. Erlang's System.monotonic_time/1 is also CLOCK_MONOTONIC-based on Linux but uses a different epoch (VM-start vs system-boot), so subtracting one from the other gives nonsense. Use now/0 here to read the same clock that stamps frames, then arithmetic on image.timestamp is meaningful.

Example — measuring chip-to-Elixir frame dwell

{:ok, image} = SSCMEx.Camera.retrieve_frame(cam, 0)
dwell_ns = SSCMEx.Tick.now() - image.timestamp
dwell_ms = div(dwell_ns, 1_000_000)

Summary

Functions

now()

Returns the current value of CLOCK_MONOTONIC in nanoseconds — the same clock and unit that SSCMEx.Image.timestamp is stamped with at frame capture time.

Functions

now()

@spec now() :: integer()

Returns the current value of CLOCK_MONOTONIC in nanoseconds — the same clock and unit that SSCMEx.Image.timestamp is stamped with at frame capture time.