Implement local solar time face
Full implementation of the local solar time complication using the pveducation.org formula set (LSTM, B, EoT, TC, LST, HRA). EoT and TC are cached by day-of-year and recomputed once at midnight rollover. Three display modes cycle with the Alarm button: SO HH:MM:SS — Local Solar Time nO HH:MM — Solar Noon in local clock time Hr ±DDD — Hour Angle in degrees Location is read from location.u32 on the filesystem. In the simulator the browser lat/lon globals are written to location.u32 on activation if not already set, fixing the "no Loc" issue in the emulator.
This commit is contained in:
Raffael Mancini
+2
-1
@@ -28,8 +28,9 @@
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#include "movement_faces.h"
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const watch_face_t watch_faces[] = {
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local_solar_time_face,
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clock_face,
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world_clock_face,
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/* world_clock_face, */
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sunrise_sunset_face,
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moon_phase_face,
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fast_stopwatch_face,
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@@ -80,4 +80,5 @@
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#include "simon_face.h"
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#include "ping_face.h"
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#include "rtccount_face.h"
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#include "local_solar_time_face.h"
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// New includes go above this line.
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@@ -55,4 +55,5 @@ SRCS += \
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./watch-faces/complication/lander_face.c \
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./watch-faces/complication/simon_face.c \
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./watch-faces/complication/ping_face.c \
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./watch-faces/complication/local_solar_time_face.c \
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# New watch faces go above this line.
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@@ -0,0 +1,227 @@
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/*
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* MIT License
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*
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* Copyright (c) 2025 Raffael Mancini
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* Solar time formulas follow the notation from:
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* https://www.pveducation.org/pvcdrom/properties-of-sunlight/solar-time
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include "local_solar_time_face.h"
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#include "watch.h"
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#include "watch_utility.h"
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#include "filesystem.h"
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#if __EMSCRIPTEN__
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#include <emscripten.h>
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#endif
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#ifndef M_PI
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#define M_PI 3.14159265358979323846f
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#endif
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/* ---------------------------------------------------------------------------
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* Solar time math (pveducation.org notation)
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* ---------------------------------------------------------------------------
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*
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* LSTM = 15 * ΔTUTC [degrees]
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* B = (360 / 365) * (d - 81) [degrees] d = day-of-year
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* EoT = 9.87*sin(2B) - 7.53*cos(B)
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* - 1.5*sin(B) [minutes]
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* TC = 4 * (Longitude - LSTM) + EoT [minutes]
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* LST = LT + TC/60 [hours]
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* HRA = 15 * (LST - 12) [degrees]
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* ---------------------------------------------------------------------------
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*/
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static movement_location_t _load_location(void) {
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movement_location_t loc = {0};
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filesystem_read_file("location.u32", (char *)&loc.reg, sizeof(loc.reg));
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return loc;
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}
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/* Compute and cache EoT and TC. Call when d != state->last_calc_d. */
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static void _compute_daily(local_solar_time_state_t *state, uint16_t d) {
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/* LSTM — movement_get_current_timezone_offset() returns seconds from UTC */
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float delta_T_UTC = (float)movement_get_current_timezone_offset() / 3600.0f;
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float LSTM = 15.0f * delta_T_UTC;
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movement_location_t loc = _load_location();
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float longitude = (float)(int16_t)loc.bit.longitude / 100.0f;
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/* B in radians for sinf/cosf */
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float B = (360.0f / 365.0f) * ((float)d - 81.0f) * ((float)M_PI / 180.0f);
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state->EoT = 9.87f * sinf(2.0f * B) - 7.53f * cosf(B) - 1.5f * sinf(B);
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state->TC = 4.0f * (longitude - LSTM) + state->EoT;
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state->last_calc_d = d;
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}
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/* Recompute if the day-of-year has rolled over. Returns current d. */
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static uint16_t _maybe_recompute(local_solar_time_state_t *state, watch_date_time_t dt) {
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uint16_t d = watch_utility_days_since_new_year(
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(uint16_t)(dt.unit.year + WATCH_RTC_REFERENCE_YEAR),
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dt.unit.month,
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dt.unit.day
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);
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if (d != state->last_calc_d && _load_location().reg != 0) {
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_compute_daily(state, d);
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}
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return d;
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}
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/* LST as total seconds since midnight (0..86399).
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* LST = LT + TC/60 => in seconds: LT_sec + TC*60 */
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static int32_t _lst_seconds(watch_date_time_t dt, float TC) {
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int32_t lt = (int32_t)dt.unit.hour * 3600
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+ (int32_t)dt.unit.minute * 60
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+ (int32_t)dt.unit.second;
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int32_t tc = (int32_t)(TC * 60.0f);
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return ((lt + tc) % 86400 + 86400) % 86400;
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}
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static void _update_display(local_solar_time_state_t *state, watch_date_time_t dt) {
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char buf[14];
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if (_load_location().reg == 0) {
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watch_display_text(WATCH_POSITION_FULL, "SO no Loc");
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return;
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}
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switch (state->mode) {
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case LOCAL_SOLAR_TIME_MODE_LST: {
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int32_t s = _lst_seconds(dt, state->TC);
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sprintf(buf, "SO %02d%02d%02d",
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(int)(s / 3600), (int)((s % 3600) / 60), (int)(s % 60));
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watch_set_colon();
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break;
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}
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case LOCAL_SOLAR_TIME_MODE_NOON: {
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/* Solar noon: moment when LST = 12:00 → LT_noon = 12h - TC/60 */
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int32_t s = (int32_t)(( 12.0f - state->TC / 60.0f) * 3600.0f);
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s = ((s % 86400) + 86400) % 86400;
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sprintf(buf, "nO %02d%02d ", (int)(s / 3600), (int)((s % 3600) / 60));
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watch_set_colon();
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break;
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}
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case LOCAL_SOLAR_TIME_MODE_HRA: {
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/* HRA = 15 * (LST - 12); negative = morning, positive = afternoon */
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int32_t s = _lst_seconds(dt, state->TC);
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int16_t hra = (int16_t)roundf(15.0f * ((float)s / 3600.0f - 12.0f));
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sprintf(buf, "Hr %+4d ", (int)hra);
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watch_clear_colon();
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break;
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}
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default:
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return;
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}
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watch_display_text(WATCH_POSITION_FULL, buf);
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}
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/* ---- Movement callbacks -------------------------------------------------- */
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void local_solar_time_face_setup(uint8_t watch_face_index, void **context_ptr) {
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(void)watch_face_index;
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if (*context_ptr == NULL) {
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*context_ptr = malloc(sizeof(local_solar_time_state_t));
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memset(*context_ptr, 0, sizeof(local_solar_time_state_t));
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/* last_calc_d == 0 guarantees recomputation on first tick */
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}
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}
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void local_solar_time_face_activate(void *context) {
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local_solar_time_state_t *state = (local_solar_time_state_t *)context;
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#if __EMSCRIPTEN__
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/* In the simulator the browser exposes lat/lon as JS globals.
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* Write them to location.u32 if not already set. */
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int16_t browser_lat = EM_ASM_INT({ return lat; });
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int16_t browser_lon = EM_ASM_INT({ return lon; });
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if (browser_lat || browser_lon) {
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movement_location_t browser_loc = {0};
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filesystem_read_file("location.u32", (char *)&browser_loc.reg, sizeof(browser_loc.reg));
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if (browser_loc.reg == 0) {
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browser_loc.bit.latitude = browser_lat;
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browser_loc.bit.longitude = browser_lon;
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filesystem_write_file("location.u32", (char *)&browser_loc.reg, sizeof(browser_loc.reg));
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}
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}
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#endif
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/* Force recompute on activation: timezone or location may have changed */
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state->last_calc_d = 0;
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watch_date_time_t dt = movement_get_local_date_time();
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_maybe_recompute(state, dt);
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}
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bool local_solar_time_face_loop(movement_event_t event, void *context) {
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local_solar_time_state_t *state = (local_solar_time_state_t *)context;
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switch (event.event_type) {
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case EVENT_ACTIVATE:
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case EVENT_TICK: {
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watch_date_time_t dt = movement_get_local_date_time();
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_maybe_recompute(state, dt);
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_update_display(state, dt);
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break;
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}
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case EVENT_ALARM_BUTTON_UP:
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state->mode = (local_solar_time_mode_t)((state->mode + 1) % LOCAL_SOLAR_TIME_NUM_MODES);
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{
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watch_date_time_t dt = movement_get_local_date_time();
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_update_display(state, dt);
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}
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break;
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case EVENT_LOW_ENERGY_UPDATE: {
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if (!watch_sleep_animation_is_running()) watch_start_sleep_animation(1000);
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watch_date_time_t dt = movement_get_local_date_time();
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_maybe_recompute(state, dt);
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_update_display(state, dt);
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break;
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}
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case EVENT_TIMEOUT:
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state->mode = LOCAL_SOLAR_TIME_MODE_LST;
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if (_load_location().reg == 0) movement_move_to_face(0);
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break;
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default:
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return movement_default_loop_handler(event);
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}
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return true;
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}
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void local_solar_time_face_resign(void *context) {
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local_solar_time_state_t *state = (local_solar_time_state_t *)context;
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state->mode = LOCAL_SOLAR_TIME_MODE_LST;
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watch_clear_colon();
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}
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@@ -0,0 +1,84 @@
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/*
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* MIT License
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*
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* Copyright (c) 2025 Raffael Mancini
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#pragma once
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/*
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* LOCAL SOLAR TIME FACE
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*
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* Displays solar time information based on the user's location.
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* Formulas follow the notation from:
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* https://www.pveducation.org/pvcdrom/properties-of-sunlight/solar-time
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*
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* Variables (pveducation.org notation):
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* LSTM - Local Standard Time Meridian [degrees] = 15 * ΔTUTC
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* B - Seasonal angle [degrees] = (360/365) * (d - 81)
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* EoT - Equation of Time [minutes] = 9.87*sin(2B) - 7.53*cos(B) - 1.5*sin(B)
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* TC - Time Correction Factor [minutes] = 4*(Longitude - LSTM) + EoT
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* LST - Local Solar Time [hours] = LT + TC/60
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* HRA - Hour Angle [degrees] = 15*(LST - 12)
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*
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* B, EoT and TC only depend on the day-of-year d, so they are cached
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* in state and recomputed exactly once per day: the cache key is d itself
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* (1-366). Zero-initialisation of state guarantees a recompute on first use.
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*
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* Requires the location to be set via the Sunrise/Sunset face, stored in
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* "location.u32" on the filesystem. If no location is set, displays
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* "SO no Loc".
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*
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* Display modes (cycle with the Alarm / start-stop button):
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* SO HH:MM:SS — Local Solar Time (LST), live seconds display
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* nO HH:MM — Solar Noon in local clock time
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* Hr ±DDD — Hour Angle (HRA) in degrees; negative=morning, positive=afternoon
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*/
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#include "movement.h"
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typedef enum {
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LOCAL_SOLAR_TIME_MODE_LST = 0, /* Local Solar Time SO HH:MM:SS */
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LOCAL_SOLAR_TIME_MODE_NOON = 1, /* Solar Noon (local) nO HH:MM */
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LOCAL_SOLAR_TIME_MODE_HRA = 2, /* Hour Angle Hr ±DDD */
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LOCAL_SOLAR_TIME_NUM_MODES
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} local_solar_time_mode_t;
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typedef struct {
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local_solar_time_mode_t mode;
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uint16_t last_calc_d; /* day-of-year (1-366) when EoT/TC were last computed;
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0 (zero-init) guarantees recomputation on first tick */
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float EoT; /* Equation of Time [minutes] */
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float TC; /* Time Correction Factor [minutes] */
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} local_solar_time_state_t;
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void local_solar_time_face_setup(uint8_t watch_face_index, void **context_ptr);
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void local_solar_time_face_activate(void *context);
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bool local_solar_time_face_loop(movement_event_t event, void *context);
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void local_solar_time_face_resign(void *context);
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#define local_solar_time_face ((const watch_face_t){ \
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local_solar_time_face_setup, \
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local_solar_time_face_activate, \
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local_solar_time_face_loop, \
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local_solar_time_face_resign, \
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NULL, \
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})
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