Bump the firmware version to 1.17.6a-zephcore and move the release
notes to RELEASE_NOTES_1.17.6a-zephcore.md, which the release workflow
publishes as the release body. The workflow's prerelease switch is
already on, so the configurator keeps offering 1.17.5c.
Notes corrected against the commits since 1.17.5c: the light-sleep
section now names the boards that sleep by default, explains the
1.17.1 DIO1 regression correctly (the button's EXT1 polarity disarmed
DIO1 on the Heltecs; the XIAO and Station G2 never had light sleep),
describes the pad holds and the USB console behaviour after the
console window, and says what the powersaving migration really does.
Added what was missing: get pm, GPS UART suspend on boards without a
power line, the optional XIAO nRF54L15 GPS, poweroff/shutdown and
get pwrmgt.*, the flush before reboot, the XIAO ESP32-S3 and Station
G2 button fixes, and a pre-release notice asking Heltec users for
light-sleep reports.
An nRF UARTE receiver starts at boot and never stops. The GPS UART
suspend in standby/off was limited to boards with GPS power control,
because suspending into a module that is still streaming NMEA could
hang the main thread waiting for RXTO (RAK3401, 1.16.6). Patch 0010
bounds that wait (4 ms, then the peripheral is disabled and the events
cleared) and resume re-arms from a clean state, so gps_power.cpp drops
the requirement: gat562_30s, muziworks_r1neo, rak3401_1watt, rak4631
and xiao_nrf54l15 now release the UART too.
Stress-tested with a temporary hook on the T1000-E, GPS streaming NMEA
at 115200: 900 suspend/resume cycles at random points of the stream,
no failure, slowest suspend 640 us (the bounded fallback never ran),
NMEA callbacks back at 1 Hz after every round.
xiao_nrf54l15 gets an optional gnss-nmea-generic on uart21 (D6/D7,
9600), as the RAK4631 and Heltec V3 have: a user-fitted GPS works on
the release image, and with nothing fitted the port, enabled upstream
and unused until now, no longer keeps its receiver armed. On the bench
unit: boots, GPS acquiring, 10 x gps off/on and two reboots clean.
Builds: rak4631 repeater and companion, rak3401_1watt, gat562_30s,
muziworks_r1neo, xiao_nrf54l15 repeater and companion.
liquidraver