Can a modern 8051 sensor node sleep without losing its periodic timing?

Trace the wakeup source to its clock domain and verify that both remain enabled in the selected mode. Review which timers, oscillators and external interrupts can operate or wake the device. Sleep-mode names and behavior vary between parts, so use the exact device manual rather than a generic 8051 description.

Include oscillator startup and sensor settling time in the measurement schedule. The first sample after wakeup may need different treatment if the analog reference or sensor was powered down. Log wake reason and timing during development, then remove diagnostic activity that would otherwise distort power measurements.

Test repeated wakeups, missed external events and reset recovery. Calculate average consumption over the full cycle, including wake overhead, instead of comparing sleep current alone. If a low-frequency timing source is used, account for its tolerance and drift when deciding whether it provides adequate long-term sample timing.