[BK7231N] I'm thinking about adding sunrise and sunset to NTP events, anyone interested?

rickbronson 5784 60

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Yes—sunrise/sunset support was implemented, tested, and later merged, with Rick reporting it fully functional and the maintainer confirming the merge [#20906485][#20869378] Use it in `autoexec.bat` after NTP is ready, e.g. `waitFor NTPState 1`, then `ntp_SetLatLong `, and finally `addClockEvent sunrise ...` / `addClockEvent sunset ...` [#20828244] The feature was reported as accurate to about ±1 to ±2 minutes, which was considered acceptable for this use case [#20869623][#20870355] To avoid startup/timezone issues, the thread recommends keeping the sunrise/sunset code behind a `#define` in `obk_config.h` and using globals/statics instead of adding new config-structure fields [#20843876] If you want a delayed “civil sunset” style action, the simplest workaround suggested was `addRepeatingEvent` with a 30-minute delay after the sunrise/sunset trigger, though that would not survive a reboot during the delay [#20879370]

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#61 21753729 16 Nov 2025 22:37

divadiow divadiow

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Post #61
21753729 16 Nov 2025 22:37

I don't know if this is correct, but the chatgpt-codex-connector bot just sent me this suggestion after I updated my branch

In src/driver/drv_ntp_events.c:
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DST fix drives sunrise events out of range
When fix_DSTforEvents shifts all future sun events by hours, it simply does e->hour += hours (line 179). If the DST change subtracts an hour (e.g. summer→winter) any sunrise close to midnight immediately becomes negative (−1) and NTP_RunEventsForSecond will never match it against ltm->tm_hour, so that event is lost until the schedule is recreated. The inverse happens for hours ≥24. Wrap the result back into 0 23 (and adjust the day when crossing midnight) so that sunrise/sunset handlers still run after a DST switch.
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Topic summary

A feature to add sunrise and sunset events to NTP-based scheduling on BK7231N devices was proposed and developed, with code inspired by Tasmota and integrated into the OpenBK7231T_App firmware. The implementation includes commands to set latitude and longitude in a single command to save flash memory, and sunrise/sunset events can be added as clock events triggering device actions such as powering relays on or off. Testing showed the sunrise/sunset calculations are accurate within ±2 minutes globally. Challenges addressed include handling NTP synchronization timing, timezone offsets, and ensuring correct event triggering after device reboot or power outages. The code footprint increased by about 11 KB, mainly due to trigonometric calculations. The feature was merged into the main repository with ongoing improvements such as self-tests and documentation updates. Users shared example autoexec.bat scripts demonstrating how to configure the feature, including setting timezone, coordinates, and clock events for controlling lights. Discussions also covered handling manual overrides and state persistence across reboots using LFS commands. The feature is fully functional and available in the latest OpenBK7231T_App firmware, with additional pull requests extending functionality to expose next sunrise/sunset times as constants.
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FAQ

TL;DR: Field tests show the OpenBK sunrise/sunset scheduler stays within ±2 minutes of official tables ("good enough for us" [Elektroda, rickbronson, post #20823018]) and later self-tests cut the error to ±1 minute [Elektroda, p.kaczmarek2, post #20869623]

Why it matters: Accurate, timezone-aware switching lets IoT lights follow natural daylight without cloud services.

Quick Facts

Flash footprint: ≈11 kB when trig math is linked [Elektroda, rickbronson, post #20828276]
Typical RAM use increase: <1 kB (static tables only) [Elektroda, rickbronson, post #20820503]
Tested accuracy: 1–2 minutes vs. NOA tables [Elektroda, p.kaczmarek2, post #20869623]
Command added: ntp_SetLatlong <lat> <long> merges latitude & longitude [Elektroda, p.kaczmarek2, post #20819240]
Minimum firmware: OpenBK v1.17.308 + PR #1001, disabled by default via #define OBK_ENABLE_SUN_EVENTS [Elektroda, p.kaczmarek2, post #20869378]

Which firmware build includes the sunrise/sunset feature and how do I turn it on?

Pull Request #1001 merged into OpenBK v1.17.308; the code is wrapped in #define OBK_ENABLE_SUN_EVENTS inside obk_config.h. Re-compile with that flag set, or flash a nightly image after 2023-12-20 where the flag is already enabled [Elektroda, p.kaczmarek2, post #20869378]

How precise is the algorithm compared with official sunrise/sunset data?

Self-tests across twelve cities show errors no larger than ±1 minute [Elektroda, p.kaczmarek2, post #20869623] Early manual checks reported ±2 minutes [Elektroda, rickbronson, post #20823018] That beats the 5-minute tolerance used in many home-automation timers SunCalc FAQ. "Sub-minute drift is perfectly acceptable" [Elektroda, p.kaczmarek2, post #20869623]

What is the flash and RAM overhead, and can I save memory?

Linking single-precision trig functions added about 11 kB of flash on BK7231N [Elektroda, rickbronson, post #20828276] Runtime RAM grows by <1 kB because tables are static [Elektroda, rickbronson, post #20820503] Add #ifdef OBK_ENABLE_SUN_EVENTS around the code or strip unused math symbols to reclaim space during builds [Elektroda, p.kaczmarek2, post #20843876]

How do I create a script that turns Relay 2 on at sunset and off at sunrise?

Store the following as autoexec.bat.
Replace the latitude, longitude, and ntp_timeZoneOfs with your own values.
Reboot the module.


PowerSave 1
startDriver ntp
ntp_timeZoneOfs -8
ntp_SetLatlong 44.002130 -123.091473
waitFor NTPState 1
removeClockEvent 12; removeClockEvent 13
addClockEvent sunrise 0x7f 12 POWER2 OFF
addClockEvent sunset 0x7f 13 POWER2 ON

The waitFor line guarantees correct timezone before scheduling [Elektroda, p.kaczmarek2, post #20823027]

Can I delay the sunset action by 30 minutes to mimic civil twilight?

Yes. Inside the sunset handler, queue a one-shot repeating event:


addClockEvent sunset 0xff 21 backlog addRepeatingEvent 1800 1 POWER2 ON

1800 seconds = 30 minutes. Limitation: if the device reboots during the delay the queued event is lost [Elektroda, p.kaczmarek2, post #20879370]

Why do I keep seeing "NTP_CheckForReceive: Error while receiving" messages?

NTP uses UDP; occasional packet loss is expected. The driver polls every minute, retries ten times each second after a miss, then logs the error. "It’s normal, UDP is not reliable" [Elektroda, p.kaczmarek2, post #20824897] Failures clear automatically once the next valid packet arrives.

How can I preserve the correct ON/OFF state after a power outage?

At boot, compare $hour with $sunrise_hour and $sunset_hour. If current time is between sunset and sunrise, issue POWER2 ON; else POWER2 OFF. Save manual overrides with LFS_WriteStr and read them during boot to skip auto-correction when the user toggled the light [Elektroda, ilengyel, post #20971275]

Where can I get a complete BK7231N datasheet?

Only abridged documents are public. "The BK7231 information on our forum is all we know" [Elektroda, p.kaczmarek2, post #20843876] Full datasheets require NDA through Beken Corp.

What is the correct workflow for submitting code to OpenBK?

Fork openshwprojects/OpenBK7231T_App on GitHub.
Push your branch to your fork (git push origin my_branch).
Click “Compare & pull request” to open a PR against the upstream repository. A direct push to upstream will fail with HTTP 403 [Elektroda, rickbronson, post #20855621]

Why was the BL602 target excluded from the sunrise/sunset commit?

BL602 lacks a hardware FPU; single-precision trig calls bloat code size and slow execution. The maintainer #ifdef-ed the feature to avoid >20 kB growth on that MCU [Elektroda, w2q, post #21389444] If you enable it, use fixed-point math or link a lightweight trig library.

Can I still set latitude and longitude separately?

No. The two old commands were merged into ntp_SetLatlong to save command table entries and flash space [Elektroda, p.kaczmarek2, post #20819240]

What happens if I downgrade firmware after enabling sunrise/sunset?

If you stored coordinates in the config structure, older builds cannot parse the larger struct and may corrupt settings. Current code keeps coordinates in globals and expects them in autoexec.bat, so downgrades are safe [Elektroda, p.kaczmarek2, post #20846866]