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light meter: rough half-working prototype

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This commit is contained in:
Joey Castillo 2025-05-18 20:32:36 -04:00
parent e511059da8
commit 94a08b531a
2 changed files with 38 additions and 17 deletions
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42
watch-faces/sensor/light_meter_face.c
View File

@ -24,6 +24,7 @@
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "light_meter_face.h"
#include "tc.h"
#include "eic.h"
@ -33,10 +34,9 @@
#ifdef HAS_IR_SENSOR
static void _light_meter_face_update_display(light_meter_state_t *state, uint8_t subsecond) {
watch_clear_display();
if (state->mode >= LIGHT_METER_MODE_AP_IS_SETTING_ISO) {
// Handle ISO settings mode.
watch_clear_display();
// Custom LCD can say "ISO". On Classic, we can't show an S in position 1, so "FI" for FIlm speed will have to suffice.
watch_display_text_with_fallback(WATCH_POSITION_TOP_LEFT, "ISO", "FI");
@ -80,7 +80,7 @@ static void _light_meter_face_update_display(light_meter_state_t *state, uint8_t
// we are in aperture or shutter priority mode.
light_meter_aperture_t aperture;
light_meter_shutter_speed_t shutter;
uint32_t light_level;
uint16_t light_level;
if (!adc_is_enabled()) {
/// TODO: need to test this more. If a background task takes a reading and disables the ADC,
@ -92,22 +92,36 @@ static void _light_meter_face_update_display(light_meter_state_t *state, uint8_t
light_level = adc_get_analog_value(HAL_GPIO_IRSENSE_pin());
/// FIXME: This curve is garbage, but in theory it was meant to convert the light level to an exposure index at ISO 25.
// Readings were taken with the custom LCD and the standard Casio light spreader in place.
// PLENTY of room for improvement here!
const float L = 63188.86f;
const float k = 0.8654f;
const float x0 = 7.45f;
const float C = 2491.21f;
float exposure_index = x0 + (1.0f / k) * log((L / ((float)light_level - C)) - 1);
if (isnan(exposure_index)) exposure_index = 0;
int8_t target_exposure_index_at_f1_or_1s = (int8_t) round(exposure_index) + state->iso;
if (state->mode == LIGHT_METER_MODE_APERTURE_PRIORITY) {
aperture = state->aperture_priority;
/// TODO: Calculate actual shutter speed
shutter = light_level * LIGHT_METER_SHUTTER_COUNT / 65535;
shutter = target_exposure_index_at_f1_or_1s - (state->aperture_priority - LIGHT_METER_APERTURE_F1);
} else {
shutter = state->shutter_priority;
/// TODO: Calculate actual aperture
aperture = light_level * LIGHT_METER_APERTURE_COUNT / 65535;
aperture = target_exposure_index_at_f1_or_1s - (state->shutter_priority - LIGHT_METER_SHUTTER_1_SEC);
}
if (shutter < LIGHT_METER_SHUTTER_1_SEC) shutter = LIGHT_METER_SHUTTER_1_SEC;
if (aperture < LIGHT_METER_APERTURE_F1) aperture = LIGHT_METER_APERTURE_F1;
// F stop is shown in both AP and SP modes.
watch_clear_display();
watch_display_text_with_fallback(WATCH_POSITION_TOP_LEFT, " F/", " F");
switch (aperture) {
case LIGHT_METER_APERTURE_F1:
watch_display_text(WATCH_POSITION_TOP_RIGHT, "1 ");
watch_display_text(WATCH_POSITION_TOP_RIGHT, " ");
watch_display_text_with_fallback(WATCH_POSITION_TOP, "TooLo", "LO");
break;
case LIGHT_METER_APERTURE_F1_4:
watch_display_text(WATCH_POSITION_TOP_RIGHT, "14");
@ -141,8 +155,8 @@ static void _light_meter_face_update_display(light_meter_state_t *state, uint8_t
case LIGHT_METER_APERTURE_F32:
watch_display_text(WATCH_POSITION_TOP_RIGHT, "32");
break;
case LIGHT_METER_APERTURE_COUNT:
// will not reach here
default:
watch_display_text_with_fallback(WATCH_POSITION_BOTTOM, "too HI", "HIGH ");
break;
}
@ -154,6 +168,10 @@ static void _light_meter_face_update_display(light_meter_state_t *state, uint8_t
}
switch (shutter) {
case LIGHT_METER_SHUTTER_1_SEC:
case LIGHT_METER_SHUTTER_1_2:
watch_display_text_with_fallback(WATCH_POSITION_BOTTOM, "tooLOw", " LO ");
break;
case LIGHT_METER_SHUTTER_1_4:
watch_display_text(WATCH_POSITION_MINUTES, " 4");
break;
@ -189,8 +207,8 @@ static void _light_meter_face_update_display(light_meter_state_t *state, uint8_t
case LIGHT_METER_SHUTTER_1_4000:
watch_display_text(WATCH_POSITION_HOURS, "40");
break;
case LIGHT_METER_SHUTTER_COUNT:
// will not reach here
default:
watch_display_text_with_fallback(WATCH_POSITION_BOTTOM, "too HI", "HIGH ");
break;
}
}

13
watch-faces/sensor/light_meter_face.h
View File

@ -32,14 +32,15 @@
* LIGHT METER
*
* EXTREME WORK IN PROGRESS on a photographic light meter.
* Currently does not display working exposure readings! This commit is just a
* user interface for the light meter, with fake readings until I calibrate it.
* Currently not even remotely calibrated! I did one afternoon of tests with light
* transmitted through the custom LCD, and half-assedly applied a curve that almost
* not not quite entirely fit the data. Pull requests welcome!
*
*/
typedef enum {
LIGHT_METER_APERTURE_F1 = 0,
LIGHT_METER_APERTURE_F1_4,
LIGHT_METER_APERTURE_F1 = -1, // f/1 will not appear as an aperture priority option
LIGHT_METER_APERTURE_F1_4, // numbered 0, f/1.4 is the first aperture priority option
LIGHT_METER_APERTURE_F2,
LIGHT_METER_APERTURE_F2_8,
LIGHT_METER_APERTURE_F4,
@ -53,7 +54,9 @@ typedef enum {
} light_meter_aperture_t;
typedef enum {
LIGHT_METER_SHUTTER_1_4 = 0,
LIGHT_METER_SHUTTER_1_SEC = -2, // 1 second and 1/2 second will not appear as a shutter priority option
LIGHT_METER_SHUTTER_1_2,
LIGHT_METER_SHUTTER_1_4, // numbered 0, 1/4 second is the first one to appear in AP list
LIGHT_METER_SHUTTER_1_8,
LIGHT_METER_SHUTTER_1_15,
LIGHT_METER_SHUTTER_1_30,