lpm_deep_standby_3_demo Directory Reference

Directory dependency graph for lpm_deep_standby_3_demo:

Directories
	src

Detailed Description

Deep Software Standby variant 3 (LPSCR.LPMD = 0xA) entry on a bare EK-RA8D2 – the deepest standby state the RA8D2 exposes. On top of the variant 2 cuts it also stops the LOCO oscillator, leaving only the always-on sub-clock-driven wake-up detectors (HUM Ch 11.1 Table 11.3 p 431-432).

The demo seeds the RTC, arms an alarm a few seconds out, programmes the deep-standby cancel matrix (DPSIER2.DRTCAIE so the alarm cancels deep standby, WUPEN0.RTCALMWUPEN so it is armed in the wake-up matrix), and enters standby.

Waking from deep standby is a reset, not a resume. Control lands back in Reset_Handler and the whole bring-up runs again, so the observable signal is a boot banner that re-emits on every wake rather than anything after the WFI. On a board whose sub-clock crystal is silent the banner emits exactly once and the WFI never returns.

That crystal is the standing caveat, shared with lpm_software_standby_demo: the RTC alarm runs off SOSC, which is intermittent on this EVM, so the automated check is deliberately boot-banner-only. It verifies the build, the bring-up and the standby-entry path; the wake itself needs a board with a live crystal. A core halted in deep standby is also unreachable to the probe, which is the other reason this is hard to gate automatically.

No external hardware required.