Display brightness support (#26)

* cleanup

* brightness control and app

* cleanup

* persistant storage of display settings

* fix for missing include

* header cleanup

* fix pc build

* add docs

* move display app to tactility project

README.md

@@ -50,7 +50,7 @@ Predefined configurations are available for:
 (*) Note: Only the capacitive version is supported. See AliExpress [here][2432s024c_1] and [here][2432s024c_2].
 
 [tdeck]: https://www.lilygo.cc/products/t-deck
-[waveshare_s3_touch]: https://www.aliexpress.com/item/1005005692235592.html
+[waveshare_s3_touch]: https://www.waveshare.com/wiki/ESP32-S3-Touch-LCD-4.3
 [2432s024c_1]: https://www.aliexpress.com/item/1005005902429049.html
 [2432s024c_2]: https://www.aliexpress.com/item/1005005865107357.html
 

app-esp/src/hello_world/hello_world.c

@@ -1,6 +1,5 @@
 #include "hello_world.h"
-#include "services/gui/gui.h"
-#include "services/loader/loader.h"
+#include "lvgl.h"
 
 static void app_show(TT_UNUSED App app, lv_obj_t* parent) {
     lv_obj_t* label = lv_label_create(parent);

boards/lilygo_tdeck/bootstrap.c

@@ -1,13 +1,11 @@
 #include "config.h"
-#include "kernel.h"
+#include "display_i.h"
+#include "driver/spi_common.h"
 #include "keyboard.h"
-#include "log.h"
-#include <driver/spi_common.h>
+#include "tactility_core.h"
 
 #define TAG "tdeck_bootstrap"
 
-lv_disp_t* tdeck_display_init();
-
 static bool tdeck_power_on() {
     gpio_config_t device_power_signal_config = {
         .pin_bit_mask = BIT64(TDECK_POWERON_GPIO),
@@ -38,8 +36,7 @@ static bool init_i2c() {
         .master.clk_speed = 400000
     };
 
-    return i2c_param_config(TDECK_I2C_BUS_HANDLE, &i2c_conf) == ESP_OK
-        && i2c_driver_install(TDECK_I2C_BUS_HANDLE, i2c_conf.mode, 0, 0, 0) == ESP_OK;
+    return i2c_param_config(TDECK_I2C_BUS_HANDLE, &i2c_conf) == ESP_OK && i2c_driver_install(TDECK_I2C_BUS_HANDLE, i2c_conf.mode, 0, 0, 0) == ESP_OK;
 }
 
 static bool init_spi() {
@@ -89,6 +86,13 @@ bool tdeck_bootstrap() {
         return false;
     }
 
+    // Don't turn the backlight on yet - Tactility init will take care of it
+    TT_LOG_I(TAG, "Init backlight");
+    if (!tdeck_backlight_init()) {
+        TT_LOG_E(TAG, "Init backlight failed");
+        return false;
+    }
+
     keyboard_wait_for_response();
 
     return true;

boards/lilygo_tdeck/display.c

@@ -9,7 +9,7 @@
 
 #define TAG "tdeck_display"
 
-void tdeck_enable_backlight() {
+bool tdeck_backlight_init() {
     ledc_timer_config_t ledc_timer = {
         .speed_mode = TDECK_LCD_BACKLIGHT_LEDC_MODE,
         .timer_num = TDECK_LCD_BACKLIGHT_LEDC_TIMER,
@@ -17,20 +17,31 @@ void tdeck_enable_backlight() {
         .freq_hz = TDECK_LCD_BACKLIGHT_LEDC_FREQUENCY,
         .clk_cfg = LEDC_AUTO_CLK
     };
-    ESP_ERROR_CHECK(ledc_timer_config(&ledc_timer));
 
+    if (ledc_timer_config(&ledc_timer) != ESP_OK) {
+        TT_LOG_E(TAG, "Backlight led timer config failed");
+        return false;
+    }
+
+    return true;
+}
+
+void tdeck_backlight_set(uint8_t duty) {
     ledc_channel_config_t ledc_channel = {
         .speed_mode = TDECK_LCD_BACKLIGHT_LEDC_MODE,
         .channel = TDECK_LCD_BACKLIGHT_LEDC_CHANNEL,
         .timer_sel = TDECK_LCD_BACKLIGHT_LEDC_TIMER,
         .intr_type = LEDC_INTR_DISABLE,
-        .gpio_num = TDECK_LCD_BACKLIGHT_LEDC_OUTPUT_IO,
-        .duty = 0, // Set duty to 0%
+        .gpio_num = TDECK_LCD_PIN_BACKLIGHT,
+        .duty = duty,
         .hpoint = 0
     };
-    ESP_ERROR_CHECK(ledc_channel_config(&ledc_channel));
 
-    ESP_ERROR_CHECK(ledc_set_duty(TDECK_LCD_BACKLIGHT_LEDC_MODE, TDECK_LCD_BACKLIGHT_LEDC_CHANNEL, TDECK_LCD_BACKLIGHT_LEDC_DUTY));
+    // Setting the config in the timer init and then calling ledc_set_duty() doesn't work when
+    // the app is running. For an unknown reason we have to call this config method every time:
+    if (ledc_channel_config(&ledc_channel) != ESP_OK) {
+        TT_LOG_E(TAG, "Failed to configure display backlight");
+    }
 }
 
 lv_disp_t* tdeck_display_init() {

boards/lilygo_tdeck/display_i.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "hal/lv_hal_disp.h"
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+lv_disp_t* tdeck_display_init();
+
+bool tdeck_backlight_init();
+
+void tdeck_backlight_set(uint8_t duty);
+
+#ifdef __cplusplus
+}
+#endif

boards/lilygo_tdeck/lilygo_tdeck.c

@@ -1,4 +1,5 @@
 #include "lilygo_tdeck.h"
+#include "display_i.h"
 #include <stdbool.h>
 
 bool tdeck_bootstrap();
@@ -8,6 +9,9 @@ extern const SdCard tdeck_sdcard;
 
 const HardwareConfig lilygo_tdeck = {
     .bootstrap = &tdeck_bootstrap,
+    .display = {
+        .set_backlight_duty = &tdeck_backlight_set
+    },
     .init_lvgl = &tdeck_init_lvgl,
     .sdcard = &tdeck_sdcard
 };

boards/lilygo_tdeck/lvgl.c

@@ -1,14 +1,13 @@
 #include "config.h"
+#include "display_i.h"
 #include "esp_lvgl_port.h"
 #include "keyboard.h"
 #include "log.h"
 #include "ui/lvgl_sync.h"
-#include <thread.h>
+#include "thread.h"
 
 #define TAG "tdeck_lvgl"
 
-lv_disp_t* tdeck_display_init();
-void tdeck_enable_backlight();
 bool tdeck_init_touch(esp_lcd_panel_io_handle_t* io_handle, esp_lcd_touch_handle_t* touch_handle);
 
 bool tdeck_init_lvgl() {
@@ -16,11 +15,9 @@ bool tdeck_init_lvgl() {
     static esp_lcd_panel_io_handle_t touch_io_handle;
     static esp_lcd_touch_handle_t touch_handle;
 
-    // Init LVGL Port library
-
     const lvgl_port_cfg_t lvgl_cfg = {
         .task_priority = THREAD_PRIORITY_RENDER,
-        .task_stack = TDECK_LVGL_TASK_STACK_DEPTH ,
+        .task_stack = TDECK_LVGL_TASK_STACK_DEPTH,
         .task_affinity = -1, // core pinning
         .task_max_sleep_ms = 500,
         .timer_period_ms = 5
@@ -66,8 +63,5 @@ bool tdeck_init_lvgl() {
 
     keyboard_alloc(display);
 
-    TT_LOG_D(TAG, "enabling backlight");
-    tdeck_enable_backlight();
-
     return true;
 }

boards/waveshare_s3_touch/waveshare_s3_touch.c

@@ -6,5 +6,8 @@ bool ws3t_bootstrap();
 
 const HardwareConfig waveshare_s3_touch = {
     .bootstrap = &ws3t_bootstrap,
+    .display = {
+        .set_backlight_duty = NULL // TODO: This requires implementing the CH422G IO expander
+    },
     .init_lvgl = &ws3t_init_lvgl
 };

boards/yellow_board/bootstrap.c

@@ -1,6 +1,6 @@
 #include "config.h"
-#include "kernel.h"
-#include "log.h"
+#include "tactility_core.h"
+#include "display_i.h"
 #include <driver/spi_common.h>
 
 #define TAG "twodotfour_bootstrap"
@@ -83,5 +83,12 @@ bool twodotfour_bootstrap() {
         return false;
     }
 
+    // Don't turn the backlight on yet - Tactility init will take care of it
+    TT_LOG_I(TAG, "Init backlight");
+    if (!twodotfour_backlight_init()) {
+        TT_LOG_E(TAG, "Init backlight failed");
+        return false;
+    }
+
     return true;
 }

boards/yellow_board/display.c

@@ -1,28 +1,56 @@
 #include "config.h"
-#include "log.h"
+#include "tactility_core.h"
+
 #include "driver/gpio.h"
+#include "driver/ledc.h"
 #include "esp_err.h"
 #include "esp_lcd_ili9341.h"
+#include "esp_lcd_panel_io.h"
 #include "esp_lcd_panel_ops.h"
 #include "esp_lvgl_port.h"
 #include "hal/lv_hal_disp.h"
-#include <esp_lcd_panel_io.h>
 
 #define TAG "twodotfour_ili9341"
 
-static void twodotfour_backlight_on() {
-    gpio_config_t io_conf = {
-        .pin_bit_mask = BIT64(TWODOTFOUR_LCD_PIN_BACKLIGHT),
-        .mode = GPIO_MODE_OUTPUT,
-        .pull_up_en = GPIO_PULLUP_DISABLE,
-        .pull_down_en = GPIO_PULLDOWN_DISABLE,
-        .intr_type = GPIO_INTR_DISABLE,
+// Dipslay backlight (PWM)
+#define TWODOTFOUR_LCD_BACKLIGHT_LEDC_TIMER LEDC_TIMER_0
+#define TWODOTFOUR_LCD_BACKLIGHT_LEDC_MODE LEDC_LOW_SPEED_MODE
+#define TWODOTFOUR_LCD_BACKLIGHT_LEDC_CHANNEL LEDC_CHANNEL_0
+#define TWODOTFOUR_LCD_BACKLIGHT_LEDC_DUTY_RES LEDC_TIMER_8_BIT
+#define TWODOTFOUR_LCD_BACKLIGHT_LEDC_FREQUENCY (1000)
+
+bool twodotfour_backlight_init() {
+    ledc_timer_config_t ledc_timer = {
+        .speed_mode = TWODOTFOUR_LCD_BACKLIGHT_LEDC_MODE,
+        .timer_num = TWODOTFOUR_LCD_BACKLIGHT_LEDC_TIMER,
+        .duty_resolution = TWODOTFOUR_LCD_BACKLIGHT_LEDC_DUTY_RES,
+        .freq_hz = TWODOTFOUR_LCD_BACKLIGHT_LEDC_FREQUENCY,
+        .clk_cfg = LEDC_AUTO_CLK
     };
 
-    gpio_config(&io_conf);
+    if (ledc_timer_config(&ledc_timer) != ESP_OK) {
+        TT_LOG_E(TAG, "Backlight led timer config failed");
+        return false;
+    }
 
-    if (gpio_set_level(TWODOTFOUR_LCD_PIN_BACKLIGHT, 1) != ESP_OK) {
-        TT_LOG_E(TAG, "Failed to turn backlight on");
+    return true;
+}
+
+void twodotfour_backlight_set(uint8_t duty) {
+    ledc_channel_config_t ledc_channel = {
+        .speed_mode = TWODOTFOUR_LCD_BACKLIGHT_LEDC_MODE,
+        .channel = TWODOTFOUR_LCD_BACKLIGHT_LEDC_CHANNEL,
+        .timer_sel = TWODOTFOUR_LCD_BACKLIGHT_LEDC_TIMER,
+        .intr_type = LEDC_INTR_DISABLE,
+        .gpio_num = TWODOTFOUR_LCD_PIN_BACKLIGHT,
+        .duty = duty,
+        .hpoint = 0
+    };
+
+    // Setting the config in the timer init and then calling ledc_set_duty() doesn't work when
+    // the app is running. For an unknown reason we have to call this config method every time:
+    if (ledc_channel_config(&ledc_channel) != ESP_OK) {
+        TT_LOG_E(TAG, "Failed to configure display backlight");
     }
 }
 
@@ -94,7 +122,5 @@ lv_disp_t* twodotfour_display_init() {
 
     lv_disp_t* display = lvgl_port_add_disp(&disp_cfg);
 
-    twodotfour_backlight_on();
-
     return display;
 }

boards/yellow_board/display_i.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+bool twodotfour_backlight_init();
+void twodotfour_backlight_set(uint8_t duty);
+
+#ifdef __cplusplus
+}
+#endif

boards/yellow_board/yellow_board.c

@@ -1,4 +1,5 @@
 #include "yellow_board.h"
+#include "display_i.h"
 
 bool twodotfour_lvgl_init();
 bool twodotfour_bootstrap();
@@ -7,6 +8,9 @@ extern const SdCard twodotfour_sdcard;
 
 const HardwareConfig yellow_board_24inch_cap = {
     .bootstrap = &twodotfour_bootstrap,
+    .display = {
+        .set_backlight_duty = &twodotfour_backlight_set
+    },
     .init_lvgl = &twodotfour_lvgl_init,
     .sdcard = &twodotfour_sdcard
 };

docs/ideas.md

@@ -7,10 +7,22 @@
 is not automatically called. This is normally done by a hook in `FreeRTOSConfig.h`
 but that seems to not work with ESP32. I should investigate task cleanup hooks further.
 - Set DPI in sdkconfig for Waveshare display
+- Try to drive Yellow Board backlight with PWM to reduce backlight strength
+- Show a warning screen if firmware encryption or secure boot are off when saving WiFi credentials.
+- Show a warning screen when a user plugs in the SD card on a device that only supports mounting at boot.
+- Try out Waveshare S3 120MHz mode for PSRAM (see "enabling 120M PSRAM is necessary" in [docs](https://www.waveshare.com/wiki/ESP32-S3-Touch-LCD-4.3#Other_Notes))
+- Fix for dark theme: the wifi icons should use the colour of the theme (they remain black when dark theme is set)
  
 # Core Ideas
 - Make a HAL? It would mainly be there to support PC development. It's a lot of effort for supporting what's effectively a dev-only feature.
 - Support for displays with different DPI. Consider the layer-based system like on Android.
+- Display orientation support for Display app
+- If present, use LED to show boot status
+
+# App Improvement Ideas
+- Make a Settings app to show all the apps that have a "settings" app type (and hide those in desktop)
+- Sort desktop apps by name.
+- Light/dark mode selection in Display settings app.
 
 # App Ideas
 - Chip 8 emulator

tactility-core/src/bundle.c

@@ -8,7 +8,7 @@
 
 typedef enum {
     BUNDLE_ENTRY_TYPE_BOOL,
-    BUNDLE_ENTRY_TYPE_INT,
+    BUNDLE_ENTRY_TYPE_INT32,
     BUNDLE_ENTRY_TYPE_STRING,
 } BundleEntryType;
 
@@ -16,7 +16,7 @@ typedef struct {
     BundleEntryType type;
     union {
         bool bool_value;
-        int int_value;
+        int32_t int32_value;
         char* string_ptr;
     };
 } BundleEntry;
@@ -28,10 +28,10 @@ BundleEntry* bundle_entry_alloc_bool(bool value) {
     return entry;
 }
 
-BundleEntry* bundle_entry_alloc_int(int value) {
+BundleEntry* bundle_entry_alloc_int32(int32_t value) {
     BundleEntry* entry = malloc(sizeof(BundleEntry));
-    entry->type = BUNDLE_ENTRY_TYPE_INT;
-    entry->int_value = value;
+    entry->type = BUNDLE_ENTRY_TYPE_INT32;
+    entry->int32_value = value;
     return entry;
 }
 
@@ -50,7 +50,7 @@ BundleEntry* bundle_entry_alloc_copy(BundleEntry* source) {
         entry->string_ptr = malloc(strlen(source->string_ptr) + 1);
         strcpy(entry->string_ptr, source->string_ptr);
     } else {
-        entry->int_value = source->int_value;
+        entry->int32_value = source->int32_value;
     }
     return entry;
 }
@@ -112,11 +112,11 @@ bool tt_bundle_get_bool(Bundle bundle, const char* key) {
     return (*entry)->bool_value;
 }
 
-int tt_bundle_get_int(Bundle bundle, const char* key) {
+int32_t tt_bundle_get_int32(Bundle bundle, const char* key) {
     BundleData* data = (BundleData*)bundle;
     BundleEntry** entry = BundleDict_get(data->dict, key);
     tt_check(entry != NULL);
-    return (*entry)->int_value;
+    return (*entry)->int32_value;
 }
 
 const char* tt_bundle_get_string(Bundle bundle, const char* key) {
@@ -126,23 +126,51 @@ const char* tt_bundle_get_string(Bundle bundle, const char* key) {
     return (*entry)->string_ptr;
 }
 
-bool tt_bundle_opt_bool(Bundle bundle, const char* key, bool* out) {
+bool tt_bundle_has_bool(Bundle bundle, const char* key) {
     BundleData* data = (BundleData*)bundle;
     BundleEntry** entry = BundleDict_get(data->dict, key);
-    if (entry != NULL) {
-        *out = (*entry)->bool_value;
-        return true;
+    return (entry != NULL) && ((*entry)->type == BUNDLE_ENTRY_TYPE_BOOL);
+}
+
+bool tt_bundle_has_int32(Bundle bundle, const char* key) {
+    BundleData* data = (BundleData*)bundle;
+    BundleEntry** entry = BundleDict_get(data->dict, key);
+    return (entry != NULL) && ((*entry)->type == BUNDLE_ENTRY_TYPE_INT32);
+}
+
+bool tt_bundle_has_string(Bundle bundle, const char* key) {
+    BundleData* data = (BundleData*)bundle;
+    BundleEntry** entry = BundleDict_get(data->dict, key);
+    return (entry != NULL) && ((*entry)->type == BUNDLE_ENTRY_TYPE_STRING);
+}
+
+bool tt_bundle_opt_bool(Bundle bundle, const char* key, bool* out) {
+    BundleData* data = (BundleData*)bundle;
+    BundleEntry** entry_ptr = BundleDict_get(data->dict, key);
+    if (entry_ptr != NULL) {
+        BundleEntry* entry = *entry_ptr;
+        if (entry->type == BUNDLE_ENTRY_TYPE_BOOL) {
+            *out = entry->bool_value;
+            return true;
+        } else {
+            return false;
+        }
     } else {
         return false;
     }
 }
 
-bool tt_bundle_opt_int(Bundle bundle, const char* key, int* out) {
+bool tt_bundle_opt_int32(Bundle bundle, const char* key, int32_t* out) {
     BundleData* data = (BundleData*)bundle;
-    BundleEntry** entry = BundleDict_get(data->dict, key);
-    if (entry != NULL) {
-        *out = (*entry)->int_value;
-        return true;
+    BundleEntry** entry_ptr = BundleDict_get(data->dict, key);
+    if (entry_ptr != NULL) {
+        BundleEntry* entry = *entry_ptr;
+        if (entry->type == BUNDLE_ENTRY_TYPE_INT32) {
+            *out = entry->int32_value;
+            return true;
+        } else {
+            return false;
+        }
     } else {
         return false;
     }
@@ -150,10 +178,15 @@ bool tt_bundle_opt_int(Bundle bundle, const char* key, int* out) {
 
 bool tt_bundle_opt_string(Bundle bundle, const char* key, char** out) {
     BundleData* data = (BundleData*)bundle;
-    BundleEntry** entry = BundleDict_get(data->dict, key);
-    if (entry != NULL) {
-        *out = (*entry)->string_ptr;
-        return true;
+    BundleEntry** entry_ptr = BundleDict_get(data->dict, key);
+    if (entry_ptr != NULL) {
+        BundleEntry* entry = *entry_ptr;
+        if (entry->type == BUNDLE_ENTRY_TYPE_STRING) {
+            *out = entry->string_ptr;
+            return true;
+        } else {
+            return false;
+        }
     } else {
         return false;
     }
@@ -172,15 +205,15 @@ void tt_bundle_put_bool(Bundle bundle, const char* key, bool value) {
     }
 }
 
-void tt_bundle_put_int(Bundle bundle, const char* key, int value) {
+void tt_bundle_put_int32(Bundle bundle, const char* key, int32_t value) {
     BundleData* data = (BundleData*)bundle;
     BundleEntry** entry_handle = BundleDict_get(data->dict, key);
     if (entry_handle != NULL) {
         BundleEntry* entry = *entry_handle;
-        tt_assert(entry->type == BUNDLE_ENTRY_TYPE_INT);
-        entry->int_value = value;
+        tt_assert(entry->type == BUNDLE_ENTRY_TYPE_INT32);
+        entry->int32_value = value;
     } else {
-        BundleEntry* entry = bundle_entry_alloc_int(value);
+        BundleEntry* entry = bundle_entry_alloc_int32(value);
         BundleDict_set_at(data->dict, key, entry);
     }
 }

tactility-core/src/bundle.h

@@ -4,8 +4,9 @@
  */
 #pragma once
 
-#include <stdio.h>
 #include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -18,15 +19,19 @@ Bundle tt_bundle_alloc_copy(Bundle source);
 void tt_bundle_free(Bundle bundle);
 
 bool tt_bundle_get_bool(Bundle bundle, const char* key);
-int tt_bundle_get_int(Bundle bundle, const char* key);
+int32_t tt_bundle_get_int32(Bundle bundle, const char* key);
 const char* tt_bundle_get_string(Bundle bundle, const char* key);
 
+bool tt_bundle_has_bool(Bundle bundle, const char* key);
+bool tt_bundle_has_int32(Bundle bundle, const char* key);
+bool tt_bundle_has_string(Bundle bundle, const char* key);
+
 bool tt_bundle_opt_bool(Bundle bundle, const char* key, bool* out);
-bool tt_bundle_opt_int(Bundle bundle, const char* key, int* out);
+bool tt_bundle_opt_int32(Bundle bundle, const char* key, int32_t* out);
 bool tt_bundle_opt_string(Bundle bundle, const char* key, char** out);
 
 void tt_bundle_put_bool(Bundle bundle, const char* key, bool value);
-void tt_bundle_put_int(Bundle bundle, const char* key, int value);
+void tt_bundle_put_int32(Bundle bundle, const char* key, int32_t value);
 void tt_bundle_put_string(Bundle bundle, const char* key, const char* value);
 
 #ifdef __cplusplus

tactility-esp/CMakeLists.txt

@@ -2,11 +2,10 @@ cmake_minimum_required(VERSION 3.16)
 
 set(BOARD_COMPONENTS esp_wifi)
 
+file(GLOB_RECURSE SOURCE_FILES src/*.c)
+
 idf_component_register(
-    SRC_DIRS "src"
-        "src/apps/system/wifi_connect"
-        "src/apps/system/wifi_manage"
-        "src/services/wifi"
+    SRCS ${SOURCE_FILES}
     INCLUDE_DIRS "src/"
     REQUIRES esp_wifi nvs_flash spiffs
 )

tactility-esp/src/apps/system/wifi_connect/wifi_connect.c

@@ -115,7 +115,7 @@ AppManifest wifi_connect_app = {
     .id = "wifi_connect",
     .name = "Wi-Fi Connect",
     .icon = NULL,
-    .type = AppTypeSystem,
+    .type = AppTypeSettings,
     .on_start = &app_start,
     .on_stop = &app_stop,
     .on_show = &app_show,

tactility-esp/src/apps/system/wifi_connect/wifi_connect_view.c

@@ -67,13 +67,9 @@ void wifi_connect_view_create_bottom_buttons(WifiConnect* wifi, lv_obj_t* parent
 void wifi_connect_view_create(App app, void* wifi, lv_obj_t* parent) {
     WifiConnect* wifi_connect = (WifiConnect*)wifi;
     WifiConnectView* view = &wifi_connect->view;
-    // TODO: Standardize this into "window content" function?
-    // TODO: It can then be dynamically determined based on screen res and size
+
     lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
-    lv_obj_set_style_pad_top(parent, 8, 0);
-    lv_obj_set_style_pad_bottom(parent, 8, 0);
-    lv_obj_set_style_pad_left(parent, 16, 0);
-    lv_obj_set_style_pad_right(parent, 16, 0);
+    tt_lv_obj_set_style_auto_padding(parent);
 
     view->root = parent;
 

tactility-esp/src/apps/system/wifi_manage/wifi_manage.c

@@ -158,7 +158,7 @@ AppManifest wifi_manage_app = {
     .id = "wifi_manage",
     .name = "Wi-Fi",
     .icon = NULL,
-    .type = AppTypeSystem,
+    .type = AppTypeSettings,
     .on_start = &app_start,
     .on_stop = &app_stop,
     .on_show = &app_show,

tactility-esp/src/apps/system/wifi_manage/wifi_manage_view.c

@@ -150,13 +150,8 @@ static void update_connected_ap(WifiManageView* view, WifiManageState* state, Wi
 void wifi_manage_view_create(WifiManageView* view, WifiManageBindings* bindings, lv_obj_t* parent) {
     view->root = parent;
 
-    // TODO: Standardize this into "window content" function?
-    // TODO: It can then be dynamically determined based on screen res and size
     lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
-    lv_obj_set_style_pad_top(parent, 8, 0);
-    lv_obj_set_style_pad_bottom(parent, 8, 0);
-    lv_obj_set_style_pad_left(parent, 16, 0);
-    lv_obj_set_style_pad_right(parent, 16, 0);
+    tt_lv_obj_set_style_auto_padding(parent);
 
     // Top row: enable/disable
     lv_obj_t* switch_container = lv_obj_create(parent);

tactility/CMakeLists.txt

@@ -23,6 +23,7 @@ if (DEFINED ENV{ESP_IDF_VERSION})
         PUBLIC idf::lvgl # libs/
         PUBLIC idf::driver
         PUBLIC idf::spiffs
+        PUBLIC idf::nvs_flash
     )
 else()
     add_definitions(-D_Nullable=)

tactility/src/apps/desktop/desktop.c

@@ -25,6 +25,8 @@ static void desktop_show(TT_UNUSED App app, TT_UNUSED lv_obj_t* parent) {
 
     lv_list_add_text(list, "System");
     tt_app_manifest_registry_for_each_of_type(AppTypeSystem, list, create_app_widget);
+    lv_list_add_text(list, "Settings");
+    tt_app_manifest_registry_for_each_of_type(AppTypeSettings, list, create_app_widget);
     lv_list_add_text(list, "User");
     tt_app_manifest_registry_for_each_of_type(AppTypeUser, list, create_app_widget);
 }

tactility/src/apps/settings/display/display.c

@@ -0,0 +1,71 @@
+#include "app.h"
+#include "lvgl.h"
+#include "preferences.h"
+#include "tactility.h"
+#include "ui/spacer.h"
+#include "ui/style.h"
+
+static bool backlight_duty_set = false;
+static uint8_t backlight_duty = 255;
+
+static void slider_event_cb(lv_event_t* e) {
+    lv_obj_t* slider = lv_event_get_target(e);
+    const Config* config = tt_get_config();
+    SetBacklightDuty set_backlight_duty = config->hardware->display.set_backlight_duty;
+
+    if (set_backlight_duty != NULL) {
+        int32_t slider_value = lv_slider_get_value(slider);
+
+        backlight_duty = (uint8_t)slider_value;
+        backlight_duty_set = true;
+
+        set_backlight_duty(backlight_duty);
+    }
+}
+
+static void app_show(TT_UNUSED App app, lv_obj_t* parent) {
+    lv_obj_set_flex_flow(parent, LV_FLEX_FLOW_COLUMN);
+    tt_lv_obj_set_style_auto_padding(parent);
+
+    lv_obj_t* label = lv_label_create(parent);
+    lv_label_set_text(label, "Brightness");
+
+    tt_lv_spacer_create(parent, 1, 2);
+
+    lv_obj_t* slider_container = lv_obj_create(parent);
+    lv_obj_set_size(slider_container, LV_PCT(100), LV_SIZE_CONTENT);
+
+    lv_obj_t* slider = lv_slider_create(slider_container);
+    lv_obj_set_width(slider, LV_PCT(90));
+    lv_obj_center(slider);
+    lv_slider_set_range(slider, 0, 255);
+    lv_obj_add_event_cb(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL);
+
+    const Config* config = tt_get_config();
+    SetBacklightDuty set_backlight_duty = config->hardware->display.set_backlight_duty;
+    if (set_backlight_duty == NULL) {
+        lv_slider_set_value(slider, 255, LV_ANIM_OFF);
+        lv_obj_add_state(slider, LV_STATE_DISABLED);
+    } else {
+        int32_t value = 255;
+        tt_preferences()->opt_int32("display", "backlight_duty", &value);
+        lv_slider_set_value(slider, value, LV_ANIM_OFF);
+    }
+}
+
+static void app_hide(App app) {
+    if (backlight_duty_set) {
+        tt_preferences()->put_int32("display", "backlight_duty", backlight_duty);
+    }
+}
+
+const AppManifest display_app = {
+    .id = "display",
+    .name = "Display",
+    .icon = NULL,
+    .type = AppTypeSettings,
+    .on_start = NULL,
+    .on_stop = NULL,
+    .on_show = &app_show,
+    .on_hide = &app_hide
+};

tactility/src/apps/system/system_info/system_info.c

@@ -1,7 +1,5 @@
-#include "app_manifest.h"
-#include "core_extra_defines.h"
+#include "app.h"
 #include "lvgl.h"
-#include "thread.h"
 
 static void app_show(TT_UNUSED App app, lv_obj_t* parent) {
     lv_obj_t* heap_info = lv_label_create(parent);

tactility/src/hardware_config.h

@@ -5,10 +5,34 @@
 
 typedef bool (*Bootstrap)();
 typedef bool (*InitLvgl)();
+typedef bool (*InitLvgl)();
+
+typedef void (*SetBacklightDuty)(uint8_t);
+typedef struct {
+    /** Set backlight duty */
+    SetBacklightDuty set_backlight_duty;
+} Display;
 
 typedef struct {
-    // Optional bootstrapping method (e.g. to turn peripherals on)
+    /**
+     * Optional bootstrapping method (e.g. to turn peripherals on)
+     * This is called after Tactility core init and before any other inits in the HardwareConfig.
+     * */
     const Bootstrap _Nullable bootstrap;
+
+    /**
+     * Initializes LVGL with all relevant hardware.
+     * This includes the display and optional pointer devices (such as touch) or a keyboard.
+     */
     const InitLvgl init_lvgl;
+
+    /**
+     * An interface for display features such as setting the backlight.
+     */
+    const Display display;
+
+    /**
+     * An optional SD card interface.
+     */
     const SdCard* _Nullable sdcard;
 } HardwareConfig;

tactility/src/preferences.c

@@ -0,0 +1,15 @@
+#include "preferences.h"
+
+#ifdef ESP_PLATFORM
+extern const Preferences preferences_esp;
+#else
+extern const Preferences preferences_memory;
+#endif
+
+const Preferences* tt_preferences() {
+#ifdef ESP_PLATFORM
+    return &preferences_esp;
+#else
+    return &preferences_memory;
+#endif
+}

tactility/src/preferences.h

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef bool (*PreferencesHasBool)(const char* namespace, const char* key);
+typedef bool (*PreferencesHasInt32)(const char* namespace, const char* key);
+typedef bool (*PreferencesHasString)(const char* namespace, const char* key);
+
+typedef bool (*PreferencesOptBool)(const char* namespace, const char* key, bool* out);
+typedef bool (*PreferencesOptInt32)(const char* namespace, const char* key, int32_t* out);
+typedef bool (*PreferencesOptString)(const char* namespace, const char* key, char* out, size_t* size);
+
+typedef void (*PreferencesPutBool)(const char* namespace, const char* key, bool value);
+typedef void (*PreferencesPutInt32)(const char* namespace, const char* key, int32_t value);
+typedef void (*PreferencesPutString)(const char* namespace, const char* key, const char* value);
+
+typedef struct {
+    PreferencesHasBool has_bool;
+    PreferencesHasInt32 has_int32;
+    PreferencesHasString has_string;
+
+    PreferencesOptBool opt_bool;
+    PreferencesOptInt32 opt_int32;
+    PreferencesOptString opt_string;
+
+    PreferencesPutBool put_bool;
+    PreferencesPutInt32 put_int32;
+    PreferencesPutString put_string;
+} Preferences;
+
+/**
+ * @return an instance of Preferences.
+ */
+const Preferences* tt_preferences();
+
+#ifdef __cplusplus
+}
+#endif

tactility/src/preferences_esp.c

@@ -0,0 +1,96 @@
+#ifdef ESP_PLATFORM
+
+#include "preferences.h"
+#include "nvs_flash.h"
+#include "tactility_core.h"
+
+static bool opt_bool(const char* namespace, const char* key, bool* out) {
+    nvs_handle_t handle;
+    if (nvs_open(namespace, NVS_READWRITE, &handle) != ESP_OK) {
+        return false;
+    } else {
+        uint8_t out_number;
+        bool success = nvs_get_u8(handle, key, &out_number) == ESP_OK;
+        nvs_close(handle);
+        if (success) {
+            *out = (bool)out_number;
+        }
+        return success;
+    }
+}
+
+static bool opt_int32(const char* namespace, const char* key, int32_t* out) {
+    nvs_handle_t handle;
+    if (nvs_open(namespace, NVS_READWRITE, &handle) != ESP_OK) {
+        return false;
+    } else {
+        bool success = nvs_get_i32(handle, key, out) == ESP_OK;
+        nvs_close(handle);
+        return success;
+    }
+}
+
+static bool opt_string(const char* namespace, const char* key, char* out, size_t* size) {
+    nvs_handle_t handle;
+    if (nvs_open(namespace, NVS_READWRITE, &handle) != ESP_OK) {
+        return false;
+    } else {
+        bool success = nvs_get_str(handle, key, out, size) == ESP_OK;
+        nvs_close(handle);
+        return success;
+    }
+}
+
+static bool has_bool(const char* namespace, const char* key) {
+    bool temp;
+    return opt_bool(namespace, key, &temp);
+}
+
+static bool has_int32(const char* namespace, const char* key) {
+    int32_t temp;
+    return opt_int32(namespace, key, &temp);
+}
+
+static bool has_string(const char* namespace, const char* key) {
+    char temp[128];
+    size_t temp_size = 128;
+    return opt_string(namespace, key, temp, &temp_size);
+}
+
+static void put_bool(const char* namespace, const char* key, bool value) {
+    nvs_handle_t handle;
+    if (nvs_open(namespace, NVS_READWRITE, &handle) == ESP_OK) {
+        nvs_set_u8(handle, key, (uint8_t)value) == ESP_OK;
+        nvs_close(handle);
+    }
+}
+
+static void put_int32(const char* namespace, const char* key, int32_t value) {
+    nvs_handle_t handle;
+    if (nvs_open(namespace, NVS_READWRITE, &handle) == ESP_OK) {
+        nvs_set_i32(handle, key, value) == ESP_OK;
+        nvs_close(handle);
+    }
+}
+
+static void put_string(const char* namespace, const char* key, const char* text) {
+    nvs_handle_t handle;
+    if (nvs_open(namespace, NVS_READWRITE, &handle) == ESP_OK) {
+        nvs_set_str(handle, key, text);
+        nvs_close(handle);
+    }
+}
+
+const Preferences preferences_esp = {
+    .has_bool = &has_bool,
+    .has_int32 = &has_int32,
+    .has_string = &has_string,
+    .opt_bool = &opt_bool,
+    .opt_int32 = &opt_int32,
+    .opt_string = &opt_string,
+    .put_bool = &put_bool,
+    .put_int32 = &put_int32,
+    .put_string = &put_string
+};
+
+#endif

tactility/src/preferences_memory.c

@@ -0,0 +1,109 @@
+#ifndef ESP_PLATFOM
+
+#include "bundle.h"
+#include "preferences.h"
+#include <string.h>
+#include <tactility_core.h>
+
+static Bundle* preferences_bundle;
+
+static Bundle* get_preferences_bundle() {
+    if (preferences_bundle == NULL) {
+        preferences_bundle = tt_bundle_alloc();
+    }
+    return preferences_bundle;
+}
+
+/**
+ * Creates a string that is effectively "namespace:key" so we can create a single map (bundle)
+ * to store all the key/value pairs.
+ *
+ * @param[in] namespace
+ * @param[in] key
+ * @param[out] out
+ */
+static void get_bundle_key(const char* namespace, const char* key, char* out) {
+    strcpy(out, namespace);
+    size_t namespace_len = strlen(namespace);
+    out[namespace_len] = ':';
+    char* out_with_key_offset = &out[namespace_len + 1];
+    strcpy(out_with_key_offset, key);
+}
+
+static bool has_bool(const char* namespace, const char* key) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_has_bool(get_preferences_bundle(), bundle_key);
+}
+
+static bool has_int32(const char* namespace, const char* key) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_has_int32(get_preferences_bundle(), bundle_key);
+}
+
+static bool has_string(const char* namespace, const char* key) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_has_string(get_preferences_bundle(), bundle_key);
+}
+
+static bool opt_bool(const char* namespace, const char* key, bool* out) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_opt_bool(get_preferences_bundle(), bundle_key, out);
+}
+
+static bool opt_int32(const char* namespace, const char* key, int32_t* out) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_opt_int32(get_preferences_bundle(), bundle_key, out);
+}
+
+static bool opt_string(const char* namespace, const char* key, char* out, size_t* size) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    char* bundle_out = NULL;
+    if (tt_bundle_opt_string(get_preferences_bundle(), bundle_key, &bundle_out)) {
+        tt_assert(bundle_out != NULL);
+        size_t found_length = strlen(bundle_out);
+        tt_check(found_length <= (*size + 1), "output buffer not large enough");
+        *size = found_length;
+        strcpy(out, bundle_out);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+static void put_bool(const char* namespace, const char* key, bool value) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_put_bool(get_preferences_bundle(), bundle_key, value);
+}
+
+static void put_int32(const char* namespace, const char* key, int32_t value) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_put_int32(get_preferences_bundle(), bundle_key, value);
+}
+
+static void put_string(const char* namespace, const char* key, const char* text) {
+    char bundle_key[128];
+    get_bundle_key(namespace, key, bundle_key);
+    return tt_bundle_put_string(get_preferences_bundle(), bundle_key, text);
+}
+
+const Preferences preferences_memory = {
+    .has_bool = &has_bool,
+    .has_int32 = &has_int32,
+    .has_string = &has_string,
+    .opt_bool = &opt_bool,
+    .opt_int32 = &opt_int32,
+    .opt_string = &opt_string,
+    .put_bool = &put_bool,
+    .put_int32 = &put_int32,
+    .put_string = &put_string
+};
+
+#endif

tactility/src/tactility.c

@@ -2,12 +2,15 @@
 
 #include "app_manifest_registry.h"
 #include "hardware_i.h"
+#include "preferences.h"
 #include "service_registry.h"
 #include "services/loader/loader.h"
 
 #define TAG "tactility"
 
-// region System services
+static const Config* config_instance = NULL;
+
+// region Default services
 
 extern const ServiceManifest gui_service;
 extern const ServiceManifest loader_service;
@@ -19,13 +22,15 @@ static const ServiceManifest* const system_services[] = {
 
 // endregion
 
-// region System apps
+// region Default apps
 
 extern const AppManifest desktop_app;
+extern const AppManifest display_app;
 extern const AppManifest system_info_app;
 
 static const AppManifest* const system_apps[] = {
     &desktop_app,
+    &display_app,
     &system_info_app
 };
 
@@ -83,6 +88,16 @@ TT_UNUSED void tt_init(const Config* config) {
 
     tt_hardware_init(config->hardware);
 
+    SetBacklightDuty set_backlight_duty = config->hardware->display.set_backlight_duty;
+    if (set_backlight_duty != NULL) {
+        int32_t backlight_duty = 200;
+        if (!tt_preferences()->opt_int32("display", "backlight_duty", &backlight_duty)) {
+            tt_preferences()->put_int32("display", "backlight_duty", backlight_duty);
+        }
+        int32_t safe_backlight_duty = TT_MIN(backlight_duty, 255);
+        set_backlight_duty((uint8_t)safe_backlight_duty);
+    }
+
     // Note: the order of starting apps and services is critical!
     // System services are registered first so the apps below can use them
     register_and_start_system_services();
@@ -103,4 +118,10 @@ TT_UNUSED void tt_init(const Config* config) {
     }
 
     TT_LOG_I(TAG, "tt_init complete");
+
+    config_instance = config;
+}
+
+const Config* _Nullable tt_get_config() {
+    return config_instance;
 }

tactility/src/tactility.h

@@ -17,8 +17,18 @@ typedef struct {
     const char* auto_start_app_id;
 } Config;
 
+/**
+ * Attempts to initialize Tactility and all configured hardware.
+ * @param config
+ */
 TT_UNUSED void tt_init(const Config* config);
 
+/**
+ * While technically nullable, this instance is always set if tt_init() succeeds.
+ * @return the Configuration instance that was passed on to tt_init() if init is successful
+ */
+const Config* _Nullable tt_get_config();
+
 #ifdef __cplusplus
 }
 #endif

tactility/src/ui/style.c

@@ -14,3 +14,10 @@ void tt_lv_obj_set_style_no_padding(lv_obj_t* obj) {
     lv_obj_set_style_pad_all(obj, LV_STATE_DEFAULT, 0);
     lv_obj_set_style_pad_gap(obj, LV_STATE_DEFAULT, 0);
 }
+
+void tt_lv_obj_set_style_auto_padding(lv_obj_t* obj) {
+    lv_obj_set_style_pad_top(obj, 8, 0);
+    lv_obj_set_style_pad_bottom(obj, 8, 0);
+    lv_obj_set_style_pad_left(obj, 16, 0);
+    lv_obj_set_style_pad_right(obj, 16, 0);
+}

tactility/src/ui/style.h

@@ -10,6 +10,15 @@ void tt_lv_obj_set_style_bg_blacken(lv_obj_t* obj);
 void tt_lv_obj_set_style_bg_invisible(lv_obj_t* obj);
 void tt_lv_obj_set_style_no_padding(lv_obj_t* obj);
 
+/**
+ * This is to create automatic padding depending on the screen size.
+ * The larger the screen, the more padding it gets.
+ * TODO: It currently only applies a single basic padding, but will be improved later.
+ *
+ * @param obj
+ */
+void tt_lv_obj_set_style_auto_padding(lv_obj_t* obj);
+
 #ifdef __cplusplus
 }
 #endif