Aperture priority light meter face (#230)

* initial commit, added opt3001 light meter test app

* tested working light meter board, i2c communication still has issues

* fixed i2c; rudimentary lightmeter works!

* added aperture priority ui

* added aperture priority ui

* added README

* adjusted cal

* fixed bugs (HI shutter speed, lux mode toggle)

* made it possible to advance to the next face

* initialized lux variable

* lowered tolerance for HI and LO

* Changed EV display from always showing EV100 to showing EV[iso setting]

* dont display old ev when ISO changes

* changed mode and light behavior

* updated readme

* fixed indentation

* made lightmeter display logic more consistent

* made lightmeter display logic more consistent

* reverted rules.mk (for merge into upstream)

* reverted rules.mk (for merge into upstream)

* removed OPT3001 PCB model

* made lux mode default, corrected timeout behavior

---------

Co-authored-by: Christian Chapman <user@debian>

5 files changed, 370 insertions, 0 deletions

diff --git a/movement/make/Makefile b/movement/make/Makefile
index d403045d..4614cd27 100644
--- a/movement/make/Makefile
+++ b/movement/make/Makefile
@@ -101,6 +101,7 @@ SRCS += \
   ../watch_faces/complication/activity_face.c \
   ../watch_faces/demo/chirpy_demo_face.c \
   ../watch_faces/complication/ships_bell_face.c \
+  ../watch_faces/sensor/lightmeter_face.c \
   ../watch_faces/complication/discgolf_face.c \
   ../watch_faces/complication/habit_face.c \
   ../watch_faces/complication/breathing_face.c \
diff --git a/movement/movement_config.h b/movement/movement_config.h
index 9e446d4d..3f6a0dc1 100644
--- a/movement/movement_config.h
+++ b/movement/movement_config.h
@@ -29,6 +29,8 @@
 
 const watch_face_t watch_faces[] = {
     simple_clock_face,
+    lightmeter_face,
+    thermistor_readout_face,
     world_clock_face,
     sunrise_sunset_face,
     moon_phase_face,
diff --git a/movement/movement_faces.h b/movement/movement_faces.h
index b8584756..afa8f14a 100644
--- a/movement/movement_faces.h
+++ b/movement/movement_faces.h
@@ -76,6 +76,7 @@
 #include "activity_face.h"
 #include "chirpy_demo_face.h"
 #include "ships_bell_face.h"
+#include "lightmeter_face.h"
 #include "discgolf_face.h"
 #include "habit_face.h"
 #include "breathing_face.h"
diff --git a/movement/watch_faces/sensor/lightmeter_face.c b/movement/watch_faces/sensor/lightmeter_face.c
new file mode 100644
index 00000000..861e28d8
--- /dev/null
+++ b/movement/watch_faces/sensor/lightmeter_face.c
@@ -0,0 +1,206 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2022 CC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/* Aperture-priority Light Meter Face
+ *
+ * Tested with the "Q3Q-SWAB-A1-00 Temperature + Test Points + OPT3001" flexboard.
+ * This flexboard could use a revision: 
+ *
+ *  - The thermistor components should be moved west a mm or flipped to the backside
+ *    to avoid stressing the flexboard against the processor so much.
+ *  - The 'no connect' pad falls off easily.
+ *
+ * Controls:
+ *
+ *  - Trigger a measurement by long-pressing Alarm.
+ *    Sensor integration is happening when the Signal indicator is on.
+ *
+ *  - ISO setting can be cycled by long-pressing Light.
+ *    During integration the current ISO setting will be displayed. 
+ *
+ *  - EV measurement in the top right: "LAP" indicates "half stop". 
+ *    So "LAP -1" means EV = -1.5. Likewise "LAP 13" means EV = +13.5  
+ *
+ *  - Aperture in the bottom right: the last 3 main digits are the f-stop. 
+ *    Adjust this number in half-stop increments using Alarm = +1/2 and Light = -1/2. 
+ *
+ *  - Best shutter speed in the bottom left: the first 3 digits are the shutter speed. 
+ *    Some special chars are needed here: "-" = seconds, "h" = extra half second, "K" = thousands.
+ *    "HI" or "LO" if there's no shutter in the dictionary within 0.5 stops of correct exposure.
+ *
+ *  - Mode long-press changes the main digits to show raw sensor lux measurements.
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include "lightmeter_face.h"
+#include "watch_utility.h"
+#include "watch_slcd.h"
+
+uint16_t lightmeter_mod(uint16_t m, uint16_t n) { return (m%n + n)%n; }  
+
+void lightmeter_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr) {
+    (void) settings;
+    (void) watch_face_index;
+    if (*context_ptr == NULL) {
+        *context_ptr = malloc(sizeof(lightmeter_state_t));
+        lightmeter_state_t *state = (lightmeter_state_t*) *context_ptr;
+        state->waiting_for_conversion = 0;
+        state->lux = 0.0;
+        state->mode = 0;
+        state->iso = LIGHTMETER_ISO_100;
+        state->ap = LIGHTMETER_AP_4P0;
+    }
+}
+
+void lightmeter_face_activate(movement_settings_t *settings, void *context) {
+    (void) settings;
+    lightmeter_state_t *state = (lightmeter_state_t*) context;
+    state->waiting_for_conversion = 0;
+    lightmeter_show_ev(state); // Print most current reading
+    watch_enable_i2c();
+    return;
+}
+
+void lightmeter_show_ev(lightmeter_state_t *state) {
+
+    float ev = max(min(
+                 log2(state->lux) + 
+                 lightmeter_isos[state->iso].ev + 
+                 LIGHTMETER_CALIBRATION,
+            99), -9);
+    int evt = round(2*ev); // Truncated EV
+
+    // Print EV
+    char strbuff[7];
+    watch_clear_all_indicators();
+    watch_display_string("EV        ", 0); 
+
+    sprintf(strbuff, "%2i", (uint16_t) abs(evt/2)); // Print whole part of EV 
+    watch_display_string(strbuff, 2); 
+    if(evt%2) watch_set_indicator(WATCH_INDICATOR_LAP); // Indicate half stop
+    if(ev<0) watch_set_pixel(1,9);  // Indicate negative EV
+
+    // Handle lux mode
+    if(state->mode == 1) {
+        sprintf(strbuff, "%6.0f", min(state->lux, 999999.0)); 
+        watch_display_string(strbuff, 4); 
+        return;
+    }
+
+    // Find and print best shutter speed
+    uint16_t bestsh = 0;
+    float besterr = 1.0/0.0;
+    float errbuf = 1.0/0.0;
+    float comp_ev = ev + lightmeter_aps[state->ap].ev; 
+    for(uint16_t ind = 2; ind < LIGHTMETER_N_SHS; ind++) {
+        errbuf = comp_ev + lightmeter_shs[ind].ev;
+        if( fabs(errbuf) < fabs(besterr)) {
+            besterr = errbuf;
+            bestsh = ind;
+        }
+    }
+    if(besterr >= 0.5) watch_display_string(lightmeter_shs[LIGHTMETER_SH_HIGH].str, 4); 
+    else if(besterr <= -0.5) watch_display_string(lightmeter_shs[LIGHTMETER_SH_LOW].str, 4); 
+    else watch_display_string(lightmeter_shs[bestsh].str, 4); 
+
+    // Print aperture
+    watch_display_string(lightmeter_aps[state->ap].str, 7); 
+    return;
+}
+
+bool lightmeter_face_loop(movement_event_t event, movement_settings_t *settings, void *context) {
+    (void) settings;
+    lightmeter_state_t *state = (lightmeter_state_t*) context;
+    
+    opt3001_Config_t c;
+    switch (event.event_type) {
+        case EVENT_TICK:
+            if(state->waiting_for_conversion) { // Check if measurement is ready...
+                c = opt3001_readConfig(lightmeter_addr);
+                if(c.ConversionReady) {
+                    state->waiting_for_conversion = 0;
+                    opt3001_t result = opt3001_readResult(lightmeter_addr);
+                    state->lux = result.lux;
+                    lightmeter_show_ev(state); 
+                } 
+            }
+            break;
+
+        case EVENT_ALARM_BUTTON_UP: // Increment aperture 
+            state->ap = lightmeter_mod(state->ap+1, LIGHTMETER_N_APS);
+
+            lightmeter_show_ev(state); 
+            break;
+
+        case EVENT_LIGHT_BUTTON_UP: // Decrement aperture 
+            if(state->ap == 0) state->ap = LIGHTMETER_N_APS-1; 
+            else state->ap = lightmeter_mod(state->ap-1, LIGHTMETER_N_APS);
+
+            lightmeter_show_ev(state); 
+            break;
+
+        case EVENT_LIGHT_LONG_PRESS: // Cycle ISO
+            state->iso = lightmeter_mod(state->iso+1, LIGHTMETER_N_ISOS);
+
+            watch_clear_all_indicators();
+            watch_display_string("EV  ", 0); 
+            watch_display_string(lightmeter_isos[state->iso].str, 4); 
+            break;
+
+        case EVENT_ALARM_LONG_PRESS: // Take measurement
+            opt3001_writeConfig(lightmeter_addr, lightmeter_takeNewReading);
+            state->waiting_for_conversion = 1;
+
+            watch_clear_all_indicators();
+            watch_display_string("EV  ", 0); 
+            watch_display_string(lightmeter_isos[state->iso].str, 4); 
+            watch_set_indicator(WATCH_INDICATOR_SIGNAL);
+            break;
+
+        case EVENT_MODE_LONG_PRESS: // Toggle mode
+            state->mode = !state->mode;
+            lightmeter_show_ev(state); 
+            break;
+
+        case EVENT_TIMEOUT:
+            movement_move_to_face(0);
+            break;
+
+        default:
+            movement_default_loop_handler(event, settings);
+            break;
+    }
+    return true;
+}
+
+void lightmeter_face_resign(movement_settings_t *settings, void *context) {
+    (void) settings;
+    (void) context;
+    opt3001_writeConfig(lightmeter_addr, lightmeter_off);
+    watch_disable_i2c();
+    return;
+}
diff --git a/movement/watch_faces/sensor/lightmeter_face.h b/movement/watch_faces/sensor/lightmeter_face.h
new file mode 100644
index 00000000..2f8813f4
--- /dev/null
+++ b/movement/watch_faces/sensor/lightmeter_face.h
@@ -0,0 +1,160 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2023 CC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef LIGHTMETER_FACE_H_
+#define LIGHTMETER_FACE_H_
+
+#include "movement.h"
+#include "opt3001.h"
+
+#define LIGHTMETER_CALIBRATION 2.58
+typedef struct { 
+    char * str;
+    float ev;
+} lightmeter_ev_t;
+
+static const lightmeter_ev_t lightmeter_isos[] = {
+    {" i  25", -2},
+    {" i  50", -1},
+    {" i 100", 0},
+    {" i 160", 0.68},
+    {" i 200", 1},
+    {" i 400", 2},
+    {" i 800", 3},
+    {" i1600", 4}};
+typedef enum { 
+    LIGHTMETER_ISO_25, LIGHTMETER_ISO_50, LIGHTMETER_ISO_100, LIGHTMETER_ISO_160, LIGHTMETER_ISO_200, LIGHTMETER_ISO_400, LIGHTMETER_ISO_800, LIGHTMETER_ISO_1600, 
+    LIGHTMETER_N_ISOS
+} lightmeter_iso_t; 
+
+static const lightmeter_ev_t lightmeter_aps[] = {
+    {"1.4", 0},
+    {"1.8", -0.5},
+    {"2.0", -1},
+    {"2.4", -1.5},
+    {"2.8", -2},
+    {"3.3", -2.5},
+    {"4.0", -3},
+    {"4.8", -3.5},
+    {"5.6", -4},
+    {"6.7", -4.5},
+    {"8.0", -5},
+    {"9.5", -5.5},
+    {"11.", -6},
+    {"13.", -6.5},
+    {"16.", -7},
+    {"19.", -7.5},
+    {"22.", -8}};
+typedef enum { 
+    LIGHTMETER_AP_1P4, LIGHTMETER_AP_1P8, LIGHTMETER_AP_2P0, LIGHTMETER_AP_2P4, LIGHTMETER_AP_2P8, LIGHTMETER_AP_3P3, LIGHTMETER_AP_4P0, LIGHTMETER_AP_4P8, LIGHTMETER_AP_5P6, LIGHTMETER_AP_6P7, LIGHTMETER_AP_8P0, LIGHTMETER_AP_9P5, 
+    LIGHTMETER_AP_11, LIGHTMETER_AP_13, LIGHTMETER_AP_16, LIGHTMETER_AP_19, LIGHTMETER_AP_22,
+    LIGHTMETER_N_APS
+} lightmeter_ap_t; 
+
+static const lightmeter_ev_t lightmeter_shs[] = {
+    {"LO-",   99},
+    {"HI ",  -99},
+    {"30-",  5.0},
+    {"20-",  4.5},
+    {"15-",  4.0},
+    {"11-",  3.5},
+    {"8- ",  3.0},
+    {"6- ",  2.5},
+    {"4- ",  2.0},
+    {"3- ",  1.5},
+    {"2- ",  1.0},
+    {"1h-",  0.5},
+    {"1  ",  0.0},
+    {"1h ", -0.5},
+    {"2  ", -1.0},
+    {"3  ", -1.5},
+    {"4  ", -2.0},
+    {"6  ", -2.5},
+    {"8  ", -3.0},
+    {"12 ", -3.5},
+    {"15 ", -4.0},
+    {"20 ", -4.5},
+    {"30 ", -5.0},
+    {"45 ", -5.5},
+    {"60 ", -6.0},
+    {"90 ", -6.5},
+    {"125", -7.0},
+    {"180", -7.5},
+    {"250", -8.0},
+    {"350", -8.5},
+    {"500", -9.0},
+    {"750", -9.5},
+    {"1K ", -10.0},
+    {"1K5", -10.5},
+    {"2K ", -11.0},
+    {"3K ", -11.5},
+    {"4K ", -12.0},
+    {"6K ", -12.5},
+    {"8K ", -13.0}};
+typedef enum { 
+    LIGHTMETER_SH_LOW, LIGHTMETER_SH_HIGH, 
+    LIGHTMETER_SH_30S, LIGHTMETER_SH_20S, LIGHTMETER_SH_15S, LIGHTMETER_SH_11S, LIGHTMETER_SH_8S, LIGHTMETER_SH_6S, LIGHTMETER_SH_3S, LIGHTMETER_SH_4S, LIGHTMETER_SH_2S, LIGHTMETER_SH_1HS, 
+    LIGHTMETER_SH_1, LIGHTMETER_SH_1H, LIGHTMETER_SH_2, LIGHTMETER_SH_3, LIGHTMETER_SH_4, LIGHTMETER_SH_6, LIGHTMETER_SH_8, LIGHTMETER_SH_12, LIGHTMETER_SH_15, LIGHTMETER_SH_20, LIGHTMETER_SH_30, LIGHTMETER_SH_45, LIGHTMETER_SH_60, LIGHTMETER_SH_90, LIGHTMETER_SH_125, LIGHTMETER_SH_180, LIGHTMETER_SH_250, LIGHTMETER_SH_350, LIGHTMETER_SH_500, LIGHTMETER_SH_750,
+    LIGHTMETER_SH_1K, LIGHTMETER_SH_1K5, LIGHTMETER_SH_2K, LIGHTMETER_SH_3K, LIGHTMETER_SH_4K, LIGHTMETER_SH_6K, LIGHTMETER_SH_8K,
+    LIGHTMETER_N_SHS
+} lightmeter_sh_t; 
+
+typedef struct {
+    lightmeter_iso_t iso;
+    lightmeter_ap_t ap;
+    bool waiting_for_conversion;
+    float lux;
+    int mode; 
+} lightmeter_state_t;
+
+static const opt3001_Config_t lightmeter_takeNewReading = { 
+    .RangeNumber = 0B1100,
+    .ConversionTime = 0B1,
+    .Latch = 0B1,
+    .ModeOfConversionOperation = 0B01
+};
+
+static const opt3001_Config_t lightmeter_off = { 
+    .ModeOfConversionOperation = 0B00
+};
+
+uint16_t lightmeter_mod(uint16_t m, uint16_t n); 
+
+void lightmeter_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);
+void lightmeter_face_activate(movement_settings_t *settings, void *context);
+void lightmeter_show_ev(lightmeter_state_t *state);
+bool lightmeter_face_loop(movement_event_t event, movement_settings_t *settings, void *context);
+void lightmeter_face_resign(movement_settings_t *settings, void *context);
+
+static const uint8_t lightmeter_addr = 0x44;
+
+#define lightmeter_face ((const watch_face_t){ \
+    lightmeter_face_setup, \
+    lightmeter_face_activate, \
+    lightmeter_face_loop, \
+    lightmeter_face_resign, \
+    NULL, \
+})
+
+#endif // LIGHTMETER_FACE_H_