Renesas FSP callback code sometimes blocks acquisition: what belongs outside the callback?

Read the specific driver's documentation and determine whether that callback executes in interrupt context. Do not assume all callbacks have the same restrictions. Measure its worst-case execution time and avoid waiting for resources that require lower-priority code to make progress.

Capture the minimum necessary status and hand work to an appropriate task or main-loop queue. Copy small values or transfer ownership of a completed buffer explicitly. Passing a pointer to storage that the peripheral immediately reuses can create a different failure while making the callback faster.

Bound the queue and count overflows. Compare producer and consumer rates under logging, communication and error handling, not just the normal case. If processing cannot keep up indefinitely, define whether to drop samples, reduce the rate or reject the operating mode.