Compile fails due to user_btn not declared in board target.
Fixes:
- Add MomentaryButton declaration for user_btn in variants/xiao_nrf52/target.cpp
- Add momentary button helper include in variants/xiao_nrf52/target.h
- Add extern linkage for MomentaryButton -> user_btn in variants/xiao_nrf52/target.h
Improvements:
- Add condition to only turn off display if on (avoids wedging the shutdown on some displays)
- Reset LoRa radio before calling radio_driver.powerOff() to ensure it is in a known good state (and will accept the command)
- Ensure SPI is started so LoRa radio commands can be sent (some shutdowns can happen before this)
- Add gate for P_LORA_NSS pin defined before writing to the pin
- Added build flag "SX126X_USE_REGULATOR_LDO" (set to 1 to enable) to use LDO for the SX1262 radio instead of DC-DC when the DCDC pin isn't wired up (e.g. t-echo lite)
- Added additional debug mode diagnostic messages during SX1262 init to better highlight faults
Added NRF52840 power management core functionality:
- Boot‑voltage lockout
- Initial support for shutdown/reset reason storage and capture (via RESETREAS/GPREGRET2)
- LPCOMP wake (for voltage-driven shutdowns)
- VBUS wake (for voltage-driven shutdowns)
- Per-board shutdown handler for board-specific tasks
- Exposed CLI queries for power‑management status in CommonCLI.cpp
- Added documentation in docs/nrf52_power_management.md.
- Enabled power management support in Xiao nRF52840, RAK4631, Heltec T114 boards
entr0p1