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commit b1191a5cfa76e5554aa9c488d97e28c112464950 Author: dechao_gong <[email protected]> AuthorDate: Wed Oct 28 10:45:32 2026 +0800 Documentation/rtl8730e: document the RTC configuration Add the RTC feature bullet and the rtc configuration section to the rtl8730e_evb board page, covering the /dev/rtc0 registration, the year plus day-of-year hardware model, the cold-start seeding and the date and alarm commands used to exercise it. Signed-off-by: dechao_gong <[email protected]> Assisted-by: Claude <[email protected]> --- .../arm/rtl8730e/boards/rtl8730e_evb/index.rst | 24 ++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/Documentation/platforms/arm/rtl8730e/boards/rtl8730e_evb/index.rst b/Documentation/platforms/arm/rtl8730e/boards/rtl8730e_evb/index.rst index dd05e6cb155..e0199e9b26f 100644 --- a/Documentation/platforms/arm/rtl8730e/boards/rtl8730e_evb/index.rst +++ b/Documentation/platforms/arm/rtl8730e/boards/rtl8730e_evb/index.rst @@ -49,6 +49,8 @@ Supported in this NuttX port: * On-chip watchdog exposed as a ``/dev/watchdog0`` character device * 12-bit ADC exposed as a ``/dev/adc0`` character device, sampled in polling mode through the SDK fwlib register layer +* On-chip RTC exposed as a ``/dev/rtc0`` character device, with a one-shot + alarm * littlefs persistent storage mounted at ``/data`` (a dedicated SPI NOR flash partition), backing the Wi-Fi key-value store * Wi-Fi station and SoftAP through the ``wapi`` tool @@ -212,6 +214,28 @@ samples, reported as raw codes. Exercise it with the example:: nsh> adc -n 1 # sample CH2-CH5 once on /dev/adc0 +rtc +--- + +Minimal NSH with the RTC driver and the ``alarm`` example +(``examples/alarm``) enabled (no Wi-Fi). The board registers the on-chip RTC +at ``/dev/rtc0`` (see ``boards/arm/rtl8730e/rtl8730e_evb/src/rtl8730e_rtc.c``) +and the system time is seeded from it at boot. The RTC has no board wiring +(it is an internal clock in the always-on domain). The hardware keeps only a +year and a day-of-year, so the driver converts to and from calendar +month/day in software. After a cold power-up the counter starts in 1900; the +driver then seeds it with ``CONFIG_START_YEAR/MONTH/DAY``, while a warm +RTC that already holds a later date is left alone. The RTC is reset by +CHIP_EN, power-on and system reset (which the board reset button +triggers), but not by BOR, thermal, deep-sleep or watchdog resets. After a +reset button press the registers therefore read back as zero (year 1900) +when the driver starts and the clock is seeded again, whereas after a +watchdog reset the time carries on. Exercise it with ``date`` and the alarm example:: + + nsh> date -s "Oct 28 12:00:00 2026" + nsh> date + nsh> alarm 5 # one-shot alarm on /dev/rtc0 firing in 5 seconds + Wi-Fi =====
