TactilityKernel improvements (#464)

* **New Features**
  * Thread API with lifecycle, priority, affinity and state monitoring
  * Timer subsystem: one-shot/periodic timers, reset, pending callbacks, expiry queries
  * Expanded I²C: register-level ops, bulk writes, presence checks, ESP32 integration and new config properties
  * GPIO controller: pin level and options APIs
  * Error utilities: new error code, error-to-string, timeout helper and common macros
  * Device construction helpers (construct+start)

* **Tests**
  * New unit tests for thread and timer behavior

* **Documentation**
  * Expanded coding style guide (files/folders, C conventions)

Buildscripts/DevicetreeCompiler/source/generator.py

@@ -135,7 +135,7 @@ def write_device_init(file, device: Device, bindings: list[Binding], verbose: bo
     identifier = get_device_identifier_safe(device)
     device_variable = identifier
     # Write device struct
-    file.write(f"\tif (init_builtin_device(&{device_variable}, \"{compatible_property.value}\") != 0) return -1;\n")
+    file.write(f"\tif (device_construct_add_start(&{device_variable}, \"{compatible_property.value}\") != ERROR_NONE) return ERROR_RESOURCE;\n")
     # Write children
     for child_device in device.devices:
         write_device_init(file, child_device, bindings, verbose)
@@ -145,7 +145,7 @@ def generate_devicetree_c(filename: str, items: list[object], bindings: list[Bin
         file.write(dedent('''\
         // Default headers
         #include <tactility/device.h>
-        #include <tactility/driver.h>
+        #include <tactility/error.h>
         #include <tactility/log.h>
         // DTS headers
         '''))
@@ -156,39 +156,17 @@ def generate_devicetree_c(filename: str, items: list[object], bindings: list[Bin
                 write_include(file, item, verbose)
         file.write("\n")
 
-        file.write(dedent('''\
-        #define TAG LOG_TAG(devicetree)
-        
-        static int init_builtin_device(struct Device* device, const char* compatible) {
-            struct Driver* driver = driver_find_compatible(compatible);
-            if (driver == NULL) {
-                LOG_E(TAG, "Can't find driver: %s", compatible);
-                return -1;
-            }
-            device_construct(device);
-            device_set_driver(device, driver);
-            device_add(device);
-            const int err = device_start(device);
-            if (err != 0) {
-                LOG_E(TAG, "Failed to start device %s with driver %s: error code %d", device->name, compatible, err);
-                return -1;
-            }
-            return 0;
-        }
-        
-        '''))
-
         # Then write all devices
         for item in items:
             if type(item) is Device:
                 write_device_structs(file, item, None, bindings, verbose)
         # Init function body start
-        file.write("int devices_builtin_init() {\n")
+        file.write("error_t devices_builtin_init() {\n")
         # Init function body logic
         for item in items:
             if type(item) is Device:
                 write_device_init(file, item, bindings, verbose)
-        file.write("\treturn 0;\n")
+        file.write("\treturn ERROR_NONE;\n")
         # Init function body end
         file.write("}\n")
 
@@ -196,12 +174,13 @@ def generate_devicetree_h(filename: str):
     with open(filename, "w") as file:
         file.write(dedent('''\
         #pragma once
+        #include <tactility/error.h>
         
         #ifdef __cplusplus
         extern "C" {
         #endif
         
-        extern int devices_builtin_init();
+        extern error_t devices_builtin_init();
         
         #ifdef __cplusplus
         }

CODING_STYLE_C.md

@@ -1,6 +1,6 @@
 # C coding Style
 
-## Naming
+## Files & Folders
 
 ### Files
 
@@ -22,6 +22,8 @@ Project folders include:
 - `private` for private header files
 - `include` for projects that require separate header files
 
+## C language
+
 ### Macros and consts
 
 These are all upper snake case:
@@ -94,3 +96,35 @@ Examples:
 ```c
 typedef uint32_t thread_id_t;
 ```
+
+### Function comments
+
+```c
+/**
+ * @brief Validates a number
+ * @param[in] number the integer to validate
+ * @return true if validation was succesful and there were no issues
+ */
+bool validate(int number);
+
+/**
+ * @brief Run the action.
+ * @param timeout[in] the maximum time the task should run
+ * @retval ERROR_TIMEOUT when the task couldn't be completed on time
+ * @retval ERROR_NONE when the task completed successfully
+ */
+error_t runAction(TickType_t timeout);
+
+/**
+ * @brief Increase a number.
+ * @param[inout] number
+ */
+void increase(int* number);
+
+/**
+ * A function with a longer description here.
+ *
+ * @brief short description
+ */
+void something();
+```

Devices/lilygo-tlora-pager/Source/Configuration.cpp

@@ -38,25 +38,6 @@ static DeviceVector createDevices() {
 extern const Configuration hardwareConfiguration = {
     .initBoot = tpagerInit,
     .createDevices = createDevices,
-    .i2c = {
-        i2c::Configuration {
-            .name = "Internal",
-            .port = I2C_NUM_0,
-            .initMode = i2c::InitMode::ByTactility,
-            .isMutable = false,
-            .config = (i2c_config_t) {
-                .mode = I2C_MODE_MASTER,
-                .sda_io_num = GPIO_NUM_3,
-                .scl_io_num = GPIO_NUM_2,
-                .sda_pullup_en = false,
-                .scl_pullup_en = false,
-                .master = {
-                    .clk_speed = 100'000
-                },
-                .clk_flags = 0
-            }
-        }
-    },
     .spi {spi::Configuration {
         .device = SPI2_HOST,
         .dma = SPI_DMA_CH_AUTO,

Devices/lilygo-tlora-pager/lilygo,tlora-pager.dts

@@ -15,9 +15,9 @@
 
 	i2c0 {
 		compatible = "espressif,esp32-i2c";
-		clock-frequency = <100000>;
-		pin-sda = <&gpio0 3 GPIO_ACTIVE_HIGH>;
-		pin-scl = <&gpio0 2 GPIO_ACTIVE_HIGH>;
 		port = <I2C_NUM_0>;
+		clock-frequency = <100000>;
+		pin-sda = <3>;
+		pin-scl = <2>;
 	};
 };

Platforms/PlatformEsp32/Bindings/espressif,esp32-i2c.yaml

@@ -10,3 +10,16 @@ properties:
     description: |
       The port number, defined by i2c_port_t.
       Depending on the hardware, these values are available: I2C_NUM_0, I2C_NUM_1, LP_I2C_NUM_0
+  clock-frequency:
+    type: int
+    description: Initial clock frequency in Hz
+  pin-sda:
+    type: int
+  pin-scl:
+    type: int
+  pin-sda-pull-up:
+    type: bool
+    description: enable internal pull-up resistor for SDA pin
+  pin-scl-pull-up:
+    type: bool
+    description: enable internal pull-up resistor for SCL pin

Platforms/PlatformEsp32/Include/tactility/drivers/esp32_i2c.h

@@ -9,12 +9,18 @@ extern "C" {
 #endif
 
 struct Esp32I2cConfig {
+    i2c_port_t port;
     uint32_t clockFrequency;
-    struct GpioPinConfig pinSda;
-    struct GpioPinConfig pinScl;
-    const i2c_port_t port;
+    gpio_pin_t pinSda;
+    gpio_pin_t pinScl;
+    bool pinSdaPullUp;
+    bool pinSclPullUp;
 };
 
+error_t esp32_i2c_get_port(struct Device* device, i2c_port_t* port);
+void esp32_i2c_lock(struct Device* device);
+void esp32_i2c_unlock(struct Device* device);
+
 #ifdef __cplusplus
 }
 #endif

Platforms/PlatformEsp32/Include/tactility/error_esp32.h

@@ -4,4 +4,5 @@
 
 #include <tactility/error.h>
 
+/** Convert an esp_err_t to an error_t */
 error_t esp_err_to_error(esp_err_t error);

Platforms/PlatformEsp32/Source/drivers/esp32_i2c.cpp

@@ -5,10 +5,12 @@
 #include <tactility/drivers/i2c_controller.h>
 #include <tactility/log.h>
 
+#include <tactility/time.h>
 #include <tactility/error_esp32.h>
 #include <tactility/drivers/esp32_i2c.h>
 
 #define TAG LOG_TAG(esp32_i2c)
+#define ACK_CHECK_EN 1
 
 struct InternalData {
     Mutex mutex { 0 };
@@ -30,46 +32,175 @@ struct InternalData {
 
 extern "C" {
 
-static int read(Device* device, uint8_t address, uint8_t* data, size_t data_size, TickType_t timeout) {
-    vPortAssertIfInISR();
+static error_t read(Device* device, uint8_t address, uint8_t* data, size_t data_size, TickType_t timeout) {
+    if (xPortInIsrContext()) return ERROR_ISR_STATUS;
+    if (data_size == 0) return ERROR_INVALID_ARGUMENT;
     auto* driver_data = GET_DATA(device);
     lock(driver_data);
     const esp_err_t esp_error = i2c_master_read_from_device(GET_CONFIG(device)->port, address, data, data_size, timeout);
     unlock(driver_data);
-    ESP_ERROR_CHECK_WITHOUT_ABORT(esp_error);
     return esp_err_to_error(esp_error);
 }
 
-static int write(Device* device, uint8_t address, const uint8_t* data, uint16_t dataSize, TickType_t timeout) {
-    vPortAssertIfInISR();
+static error_t write(Device* device, uint8_t address, const uint8_t* data, uint16_t data_size, TickType_t timeout) {
+    if (xPortInIsrContext()) return ERROR_ISR_STATUS;
+    if (data_size == 0) return ERROR_INVALID_ARGUMENT;
     auto* driver_data = GET_DATA(device);
     lock(driver_data);
-    const esp_err_t esp_error = i2c_master_write_to_device(GET_CONFIG(device)->port, address, data, dataSize, timeout);
+    const esp_err_t esp_error = i2c_master_write_to_device(GET_CONFIG(device)->port, address, data, data_size, timeout);
     unlock(driver_data);
-    ESP_ERROR_CHECK_WITHOUT_ABORT(esp_error);
     return esp_err_to_error(esp_error);
 }
 
-static int write_read(Device* device, uint8_t address, const uint8_t* write_data, size_t write_data_size, uint8_t* read_data, size_t read_data_size, TickType_t timeout) {
-    vPortAssertIfInISR();
+static error_t write_read(Device* device, uint8_t address, const uint8_t* write_data, size_t write_data_size, uint8_t* read_data, size_t read_data_size, TickType_t timeout) {
+    if (xPortInIsrContext()) return ERROR_ISR_STATUS;
+    if (write_data_size == 0 || read_data_size == 0) return ERROR_INVALID_ARGUMENT;
     auto* driver_data = GET_DATA(device);
     lock(driver_data);
     const esp_err_t esp_error = i2c_master_write_read_device(GET_CONFIG(device)->port, address, write_data, write_data_size, read_data, read_data_size, timeout);
     unlock(driver_data);
-    ESP_ERROR_CHECK_WITHOUT_ABORT(esp_error);
     return esp_err_to_error(esp_error);
 }
 
-static int start(Device* device) {
+static error_t read_register(Device* device, uint8_t address, uint8_t reg, uint8_t* data, size_t data_size, TickType_t timeout) {
+    auto start_time = get_ticks();
+    if (xPortInIsrContext()) return ERROR_ISR_STATUS;
+    if (data_size == 0) return ERROR_INVALID_ARGUMENT;
+    auto* driver_data = GET_DATA(device);
+
+    lock(driver_data);
+    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
+    esp_err_t error = ESP_OK;
+    if (cmd == nullptr) {
+        error = ESP_ERR_NO_MEM;
+        goto on_error;
+    }
+    // Set address pointer
+    error = i2c_master_start(cmd);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_WRITE, ACK_CHECK_EN);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_write(cmd, &reg, 1, ACK_CHECK_EN);
+    if (error != ESP_OK) goto on_error;
+    // Read length of response from current pointer
+    error = i2c_master_start(cmd);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_READ, ACK_CHECK_EN);
+    if (error != ESP_OK) goto on_error;
+    if (data_size > 1) {
+        error = i2c_master_read(cmd, data, data_size - 1, I2C_MASTER_ACK);
+        if (error != ESP_OK) goto on_error;
+    }
+    error = i2c_master_read_byte(cmd, data + data_size - 1, I2C_MASTER_NACK);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_stop(cmd);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_cmd_begin(GET_CONFIG(device)->port, cmd, get_timeout_remaining_ticks(timeout, start_time));
+    if (error != ESP_OK) goto on_error;
+
+    i2c_cmd_link_delete(cmd);
+    unlock(driver_data);
+    return esp_err_to_error(error);
+
+on_error:
+    i2c_cmd_link_delete(cmd);
+    unlock(driver_data);
+    return esp_err_to_error(error);
+}
+
+static error_t write_register(Device* device, uint8_t address, uint8_t reg, const uint8_t* data, uint16_t data_size, TickType_t timeout) {
+    auto start_time = get_ticks();
+    if (xPortInIsrContext()) return ERROR_ISR_STATUS;
+    if (data_size == 0) return ERROR_INVALID_ARGUMENT;
+    auto* driver_data = GET_DATA(device);
+
+    lock(driver_data);
+    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
+    esp_err_t error = ESP_OK;
+    if (cmd == nullptr) {
+        error = ESP_ERR_NO_MEM;
+        goto on_error;
+    }
+    error = i2c_master_start(cmd);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_WRITE, ACK_CHECK_EN);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_write_byte(cmd, reg, ACK_CHECK_EN);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_write(cmd, (uint8_t*) data, data_size, ACK_CHECK_EN);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_stop(cmd);
+    if (error != ESP_OK) goto on_error;
+    error = i2c_master_cmd_begin(GET_CONFIG(device)->port, cmd, get_timeout_remaining_ticks(timeout, start_time));
+    if (error != ESP_OK) goto on_error;
+
+    i2c_cmd_link_delete(cmd);
+    unlock(driver_data);
+    return esp_err_to_error(error);
+
+on_error:
+    i2c_cmd_link_delete(cmd);
+    unlock(driver_data);
+    return esp_err_to_error(error);
+}
+
+error_t esp32_i2c_get_port(struct Device* device, i2c_port_t* port) {
+    auto* config = GET_CONFIG(device);
+    *port = config->port;
+    return ERROR_NONE;
+}
+
+void esp32_i2c_lock(struct Device* device) {
+    mutex_lock(&GET_DATA(device)->mutex);
+}
+
+void esp32_i2c_unlock(struct Device* device) {
+    mutex_unlock(&GET_DATA(device)->mutex);
+}
+
+static error_t start(Device* device) {
     ESP_LOGI(TAG, "start %s", device->name);
+    auto dts_config = GET_CONFIG(device);
+
+    i2c_config_t esp_config = {
+        .mode = I2C_MODE_MASTER,
+        .sda_io_num = dts_config->pinSda,
+        .scl_io_num = dts_config->pinScl,
+        .sda_pullup_en = dts_config->pinSdaPullUp,
+        .scl_pullup_en = dts_config->pinSclPullUp,
+        .master {
+            .clk_speed = dts_config->clockFrequency
+        },
+        .clk_flags = 0
+    };
+
+    esp_err_t error = i2c_param_config(dts_config->port, &esp_config);
+    if (error != ESP_OK) {
+        LOG_E(TAG, "Failed to configure port %d: %s", static_cast<int>(dts_config->port), esp_err_to_name(error));
+        return ERROR_RESOURCE;
+    }
+
+    error = i2c_driver_install(dts_config->port, esp_config.mode, 0, 0, 0);
+    if (error != ESP_OK) {
+        LOG_E(TAG, "Failed to install driver at port %d: %s", static_cast<int>(dts_config->port), esp_err_to_name(error));
+        return ERROR_RESOURCE;
+    }
     auto* data = new InternalData();
     device_set_driver_data(device, data);
     return ERROR_NONE;
 }
 
-static int stop(Device* device) {
+static error_t stop(Device* device) {
     ESP_LOGI(TAG, "stop %s", device->name);
     auto* driver_data = static_cast<InternalData*>(device_get_driver_data(device));
+
+    i2c_port_t port = GET_CONFIG(device)->port;
+    esp_err_t result = i2c_driver_delete(port);
+    if (result != ESP_OK) {
+        LOG_E(TAG, "Failed to delete driver at port %d: %s", static_cast<int>(port), esp_err_to_name(result));
+        return ERROR_RESOURCE;
+    }
+
     device_set_driver_data(device, nullptr);
     delete driver_data;
     return ERROR_NONE;
@@ -78,7 +209,9 @@ static int stop(Device* device) {
 const static I2cControllerApi esp32_i2c_api = {
     .read = read,
     .write = write,
-    .write_read = write_read
+    .write_read = write_read,
+    .read_register = read_register,
+    .write_register = write_register
 };
 
 Driver esp32_i2c_driver = {

Platforms/PlatformEsp32/Source/error_esp32.cpp

@@ -11,6 +11,10 @@ error_t esp_err_to_error(esp_err_t error) {
             return ERROR_INVALID_STATE;
         case ESP_ERR_TIMEOUT:
             return ERROR_TIMEOUT;
+        case ESP_ERR_NO_MEM:
+            return ERROR_OUT_OF_MEMORY;
+        case ESP_ERR_NOT_SUPPORTED:
+            return ERROR_NOT_SUPPORTED;
         default:
             return ERROR_UNDEFINED;
     }

Tactility/CMakeLists.txt

@@ -5,6 +5,7 @@ if (DEFINED ENV{ESP_IDF_VERSION})
 
     list(APPEND REQUIRES_LIST
         TactilityKernel
+        PlatformEsp32
         TactilityCore
         TactilityFreeRtos
         lvgl
@@ -54,31 +55,27 @@ else()
 
     add_library(Tactility OBJECT)
 
-    target_sources(Tactility
-        PRIVATE ${SOURCES}
-    )
-
-    include_directories(
-        PRIVATE Private/
-    )
+    target_sources(Tactility PRIVATE ${SOURCES})
 
     target_include_directories(Tactility
+        PRIVATE Private/
         PUBLIC Include/
     )
 
     add_definitions(-D_Nullable=)
     add_definitions(-D_Nonnull=)
 
-    target_link_libraries(Tactility
-        PUBLIC cJSON
-        PUBLIC TactilityFreeRtos
-        PUBLIC TactilityCore
-        PUBLIC TactilityKernel
-        PUBLIC freertos_kernel
-        PUBLIC lvgl
-        PUBLIC lv_screenshot
-        PUBLIC minmea
-        PUBLIC minitar
+    target_link_libraries(Tactility PUBLIC
+        cJSON
+        TactilityFreeRtos
+        TactilityCore
+        TactilityKernel
+        PlatformPosix
+        freertos_kernel
+        lvgl
+        lv_screenshot
+        minmea
+        minitar
     )
 endif()
 

Tactility/Include/Tactility/hal/i2c/I2c.h

@@ -14,7 +14,6 @@ constexpr TickType_t defaultTimeout = 10 / portTICK_PERIOD_MS;
 
 enum class InitMode {
     ByTactility, // Tactility will initialize it in the correct bootup phase
-    ByExternal, // The device is already initialized and Tactility should assume it works
     Disabled // Not initialized by default
 };
 
@@ -39,15 +38,6 @@ enum class Status {
     Unknown
 };
 
-/**
- * Reconfigure a port with the provided settings.
- * @warning This fails when the HAL Configuration is not mutable.
- * @param[in] port the port to reconfigure
- * @param[in] configuration the new configuration
- * @return true on success
- */
-bool configure(i2c_port_t port, const i2c_config_t& configuration);
-
 /**
  * Start the bus for the specified port.
  * Devices might be started automatically at boot if their HAL configuration requires it.
@@ -60,6 +50,9 @@ bool stop(i2c_port_t port);
 /** @return true if the bus is started */
 bool isStarted(i2c_port_t port);
 
+/** @return name or nullptr */
+const char* getName(i2c_port_t port);
+
 /** Read bytes in master mode. */
 bool masterRead(i2c_port_t port, uint8_t address, uint8_t* data, size_t dataSize, TickType_t timeout = defaultTimeout);
 

Tactility/Private/Tactility/app/i2cscanner/I2cHelpers.h

@@ -9,4 +9,6 @@ std::string getAddressText(uint8_t address);
 
 std::string getPortNamesForDropdown();
 
+bool getActivePortAtIndex(int32_t index, int32_t& out);
+
 }

Tactility/Source/Tactility.cpp

@@ -74,16 +74,13 @@ namespace service {
 
 namespace app {
     namespace addgps { extern const AppManifest manifest; }
+    namespace alertdialog { extern const AppManifest manifest; }
     namespace apphub { extern const AppManifest manifest; }
     namespace apphubdetails { extern const AppManifest manifest; }
-    namespace alertdialog { extern const AppManifest manifest; }
     namespace appdetails { extern const AppManifest manifest; }
     namespace applist { extern const AppManifest manifest; }
     namespace appsettings { extern const AppManifest manifest; }
     namespace boot { extern const AppManifest manifest; }
-#if defined(CONFIG_SOC_WIFI_SUPPORTED) && !defined(CONFIG_SLAVE_SOC_WIFI_SUPPORTED)
-    namespace chat { extern const AppManifest manifest; }
-#endif
     namespace development { extern const AppManifest manifest; }
     namespace display { extern const AppManifest manifest; }
     namespace files { extern const AppManifest manifest; }
@@ -94,9 +91,6 @@ namespace app {
     namespace imageviewer { extern const AppManifest manifest; }
     namespace inputdialog { extern const AppManifest manifest; }
     namespace launcher { extern const AppManifest manifest; }
-#if defined(ESP_PLATFORM) && defined(CONFIG_TT_DEVICE_LILYGO_TDECK)
-    namespace keyboardsettings { extern const AppManifest manifest; }
-#endif
     namespace localesettings { extern const AppManifest manifest; }
     namespace notes { extern const AppManifest manifest; }
     namespace power { extern const AppManifest manifest; }
@@ -105,21 +99,27 @@ namespace app {
     namespace systeminfo { extern const AppManifest manifest; }
     namespace timedatesettings { extern const AppManifest manifest; }
     namespace timezone { extern const AppManifest manifest; }
-#if defined(ESP_PLATFORM) && defined(CONFIG_TT_DEVICE_LILYGO_TDECK)
-    namespace trackballsettings { extern const AppManifest manifest; }
-#endif
     namespace usbsettings { extern const AppManifest manifest; }
     namespace wifiapsettings { extern const AppManifest manifest; }
     namespace wificonnect { extern const AppManifest manifest; }
     namespace wifimanage { extern const AppManifest manifest; }
+
 #ifdef ESP_PLATFORM
+    namespace crashdiagnostics { extern const AppManifest manifest; }
     namespace webserversettings { extern const AppManifest manifest; }
 #endif
+
+#if defined(ESP_PLATFORM) && defined(CONFIG_TT_DEVICE_LILYGO_TDECK)
+    namespace keyboardsettings { extern const AppManifest manifest; }
+    namespace trackballsettings { extern const AppManifest manifest; }
+#endif
+
 #if TT_FEATURE_SCREENSHOT_ENABLED
     namespace screenshot { extern const AppManifest manifest; }
 #endif
-#ifdef ESP_PLATFORM
-    namespace crashdiagnostics { extern const AppManifest manifest; }
+
+#if defined(CONFIG_SOC_WIFI_SUPPORTED) && !defined(CONFIG_SLAVE_SOC_WIFI_SUPPORTED)
+    namespace chat { extern const AppManifest manifest; }
 #endif
 }
 
@@ -138,12 +138,11 @@ static void registerInternalApps() {
     addAppManifest(app::display::manifest);
     addAppManifest(app::files::manifest);
     addAppManifest(app::fileselection::manifest);
+    addAppManifest(app::i2cscanner::manifest);
+    addAppManifest(app::i2csettings::manifest);
     addAppManifest(app::imageviewer::manifest);
     addAppManifest(app::inputdialog::manifest);
     addAppManifest(app::launcher::manifest);
-#if defined(ESP_PLATFORM) && defined(CONFIG_TT_DEVICE_LILYGO_TDECK)
-    addAppManifest(app::keyboardsettings::manifest);
-#endif
     addAppManifest(app::localesettings::manifest);
     addAppManifest(app::notes::manifest);
     addAppManifest(app::settings::manifest);
@@ -151,14 +150,19 @@ static void registerInternalApps() {
     addAppManifest(app::systeminfo::manifest);
     addAppManifest(app::timedatesettings::manifest);
     addAppManifest(app::timezone::manifest);
-#if defined(ESP_PLATFORM) && defined(CONFIG_TT_DEVICE_LILYGO_TDECK)
-    addAppManifest(app::trackballsettings::manifest);
-#endif
     addAppManifest(app::wifiapsettings::manifest);
     addAppManifest(app::wificonnect::manifest);
     addAppManifest(app::wifimanage::manifest);
+
 #ifdef ESP_PLATFORM
     addAppManifest(app::webserversettings::manifest);
+    addAppManifest(app::crashdiagnostics::manifest);
+    addAppManifest(app::development::manifest);
+#endif
+
+#if defined(ESP_PLATFORM) && defined(CONFIG_TT_DEVICE_LILYGO_TDECK)
+    addAppManifest(app::keyboardsettings::manifest);
+    addAppManifest(app::trackballsettings::manifest);
 #endif
 
 #if defined(CONFIG_TINYUSB_MSC_ENABLED) && CONFIG_TINYUSB_MSC_ENABLED
@@ -173,16 +177,6 @@ static void registerInternalApps() {
     addAppManifest(app::chat::manifest);
 #endif
 
-#ifdef ESP_PLATFORM
-    addAppManifest(app::crashdiagnostics::manifest);
-    addAppManifest(app::development::manifest);
-#endif
-
-    if (!hal::getConfiguration()->i2c.empty()) {
-        addAppManifest(app::i2cscanner::manifest);
-        addAppManifest(app::i2csettings::manifest);
-    }
-
     if (!hal::getConfiguration()->uart.empty()) {
         addAppManifest(app::addgps::manifest);
         addAppManifest(app::gpssettings::manifest);

Tactility/Source/app/i2cscanner/I2cHelpers.cpp

@@ -19,18 +19,31 @@ std::string getAddressText(uint8_t address) {
 
 std::string getPortNamesForDropdown() {
     std::vector<std::string> config_names;
-    size_t port_index = 0;
-    for (const auto& i2c_config: tt::getConfiguration()->hardware->i2c) {
-        if (!i2c_config.name.empty()) {
-            config_names.push_back(i2c_config.name);
-        } else {
-            std::stringstream stream;
-            stream << "Port " << std::to_string(port_index);
-            config_names.push_back(stream.str());
+    for (int port = 0; port < I2C_NUM_MAX; ++port) {
+        auto native_port = static_cast<i2c_port_t>(port);
+        if (hal::i2c::isStarted(native_port)) {
+            auto* name = hal::i2c::getName(native_port);
+            if (name != nullptr) {
+                config_names.push_back(name);
+            }
         }
-        port_index++;
     }
     return string::join(config_names, "\n");
 }
 
+bool getActivePortAtIndex(int32_t index, int32_t& out) {
+    int current_index = -1;
+    for (int port = 0; port < I2C_NUM_MAX; ++port) {
+        auto native_port = static_cast<i2c_port_t>(port);
+        if (hal::i2c::isStarted(native_port)) {
+            current_index++;
+            if (current_index == index) {
+                out = port;
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
 }

Tactility/Source/app/i2cscanner/I2cScanner.cpp

@@ -141,11 +141,10 @@ void I2cScannerApp::onShow(AppContext& app, lv_obj_t* parent) {
     lv_obj_add_flag(scan_list, LV_OBJ_FLAG_HIDDEN);
     scanListWidget = scan_list;
 
-    auto i2c_devices = getConfiguration()->hardware->i2c;
-    if (!i2c_devices.empty()) {
-        assert(selected_bus < i2c_devices.size());
-        port = i2c_devices[selected_bus].port;
-        selectBus(selected_bus);
+    int32_t first_port;
+    if (getActivePortAtIndex(0, first_port)) {
+        lv_dropdown_set_selected(port_dropdown, 0);
+        selectBus(0);
     }
 }
 
@@ -307,12 +306,14 @@ void I2cScannerApp::onSelectBus(lv_event_t* event) {
 }
 
 void I2cScannerApp::selectBus(int32_t selected) {
-    auto i2c_devices = getConfiguration()->hardware->i2c;
-    assert(selected < i2c_devices.size());
+    int32_t found_port;
+    if (!getActivePortAtIndex(selected, found_port)) {
+        return;
+    }
 
     if (mutex.lock(100 / portTICK_PERIOD_MS)) {
         scannedAddresses.clear();
-        port = i2c_devices[selected].port;
+        port = static_cast<i2c_port_t>(found_port);
         scanState = ScanStateInitial;
         mutex.unlock();
     }

Tactility/Source/hal/i2c/I2c.cpp

@@ -2,7 +2,14 @@
 
 #include <Tactility/Logger.h>
 #include <Tactility/Mutex.h>
+
 #include <tactility/check.h>
+#include <tactility/drivers/i2c_controller.h>
+#include <tactility/time.h>
+
+#ifdef ESP_PLATFORM
+#include <tactility/drivers/esp32_i2c.h>
+#endif
 
 namespace tt::hal::i2c {
 
@@ -11,270 +18,250 @@ static const auto LOGGER = Logger("I2C");
 struct Data {
     Mutex mutex;
     bool isConfigured = false;
-    bool isStarted = false;
-    Configuration configuration;
+    Device* device = nullptr;
+#ifdef ESP_PLATFORM
+    Esp32I2cConfig config = {
+        .port = I2C_NUM_0,
+        .clockFrequency = 0,
+        .pinSda = 0,
+        .pinScl = 0,
+        .pinSdaPullUp = false,
+        .pinSclPullUp = false
+    };
+#endif
 };
 
-static const uint8_t ACK_CHECK_EN = 1;
 static Data dataArray[I2C_NUM_MAX];
 
+#ifdef ESP_PLATFORM
+void registerDriver(Data& data, const Configuration& configuration) {
+    // Should only be called on init
+    check(data.device == nullptr);
+
+    data.config.port = configuration.port;
+    data.config.clockFrequency = configuration.config.master.clk_speed;
+    data.config.pinSda = configuration.config.sda_io_num;
+    data.config.pinScl = configuration.config.scl_io_num;
+    data.config.pinSdaPullUp = configuration.config.sda_pullup_en;
+    data.config.pinSclPullUp = configuration.config.scl_pullup_en;
+
+    data.device = new Device();
+    data.device->name = configuration.name.c_str();
+    data.device->config = &data.config;
+    data.device->parent = nullptr;
+
+    if (device_construct_add(data.device, "espressif,esp32-i2c") == ERROR_NONE) {
+        data.isConfigured = true;
+    }
+}
+
+Device* findExistingKernelDevice(i2c_port_t port) {
+    struct Params {
+        i2c_port_t port;
+        Device* device;
+    };
+
+    Params params = {
+        .port = port,
+        .device = nullptr
+    };
+
+    for_each_device_of_type(&I2C_CONTROLLER_TYPE, &params, [](auto* device, auto* context) {
+        auto* params_ptr = (Params*)context;
+        auto* driver = device_get_driver(device);
+        if (driver == nullptr) return true;
+        if (!driver_is_compatible(driver, "espressif,esp32-i2c")) return true;
+        i2c_port_t port;
+        if (esp32_i2c_get_port(device, &port) != ERROR_NONE) return true;
+        if (port != params_ptr->port) return true;
+        // Found it, stop iterating
+        params_ptr->device = device;
+        return false;
+    });
+
+    return params.device;
+}
+#endif
+
 bool init(const std::vector<Configuration>& configurations) {
    LOGGER.info("Init");
-   for (const auto& configuration: configurations) {
 #ifdef ESP_PLATFORM
+    bool found_existing = false;
+    for (int port = 0; port < I2C_NUM_MAX; ++port) {
+        auto native_port = static_cast<i2c_port_t>(port);
+        auto existing_device = findExistingKernelDevice(native_port);
+        if (existing_device != nullptr) {
+            LOGGER.info("Initialized port {} with existing kernel device", port);
+            auto& data = dataArray[port];
+            data.device = existing_device;
+            data.isConfigured = true;
+            memcpy(&data.config, existing_device->config, sizeof(Esp32I2cConfig));
+            // Ensure we don't initialize
+            found_existing = true;
+        }
+    }
+
+    // Nothing found in HAL, so try configuration
+    for (const auto& configuration: configurations) {
+        check(!found_existing, "hal::Configuration specifies I2C, but I2C was already initialized by devicetree. Remove the hal::Configuration I2C entries!");
         if (configuration.config.mode != I2C_MODE_MASTER) {
             LOGGER.error("Currently only master mode is supported");
             return false;
         }
-#endif // ESP_PLATFORM
         Data& data = dataArray[configuration.port];
-       data.configuration = configuration;
-       data.isConfigured = true;
+        registerDriver(data, configuration);
     }
 
+    if (!found_existing) {
         for (const auto& config: configurations) {
             if (config.initMode == InitMode::ByTactility) {
                 if (!start(config.port)) {
                     return false;
                 }
-       } else if (config.initMode == InitMode::ByExternal) {
-           dataArray[config.port].isStarted = true;
+            }
         }
     }
 
+#endif
     return true;
 }
 
-bool configure(i2c_port_t port, const i2c_config_t& configuration) {
-    auto lock = getLock(port).asScopedLock();
-    lock.lock();
-
-    Data& data = dataArray[port];
-    if (data.isStarted) {
-        LOGGER.error("({}) Cannot reconfigure while interface is started", static_cast<int>(port));
-        return false;
-    } else if (!data.configuration.isMutable) {
-        LOGGER.error("({}) Mutation not allowed because configuration is immutable", static_cast<int>(port));
-        return false;
-    } else {
-        data.configuration.config = configuration;
-        return true;
-    }
-}
-
 bool start(i2c_port_t port) {
+#ifdef ESP_PLATFORM
     auto lock = getLock(port).asScopedLock();
     lock.lock();
 
     Data& data = dataArray[port];
-    Configuration& config = data.configuration;
-
-    if (data.isStarted) {
-        LOGGER.error("({}) Starting: Already started", static_cast<int>(port));
-        return false;
-    }
 
     if (!data.isConfigured) {
         LOGGER.error("({}) Starting: Not configured", static_cast<int>(port));
         return false;
     }
 
-#ifdef ESP_PLATFORM
-    esp_err_t result = i2c_param_config(port, &config.config);
-    if (result != ESP_OK) {
-        LOGGER.error("({}) Starting: Failed to configure: {}", static_cast<int>(port), esp_err_to_name(result));
+    check(data.device);
+
+    error_t error = device_start(data.device);
+    if (error != ERROR_NONE) {
+        LOGGER.error("Failed to start device {}: {}", data.device->name, error_to_string(error));
         return false;
     }
 
-    result = i2c_driver_install(port, config.config.mode, 0, 0, 0);
-    if (result != ESP_OK) {
-        LOGGER.error("({}) Starting: Failed to install driver: {}", static_cast<int>(port), esp_err_to_name(result));
-        return false;
-    }
-#endif // ESP_PLATFORM
-
-    data.isStarted = true;
-
-    LOGGER.info("({}) Started", static_cast<int>(port));
     return true;
+#else
+    return false;
+#endif
 }
 
 bool stop(i2c_port_t port) {
+#ifdef ESP_PLATFORM
     auto lock = getLock(port).asScopedLock();
     lock.lock();
 
     Data& data = dataArray[port];
-    Configuration& config = data.configuration;
-
-    if (!config.isMutable) {
-        LOGGER.error("({}) Stopping: Not allowed for immutable configuration", static_cast<int>(port));
+    if (!dataArray[port].isConfigured) return false;
+    return device_stop(data.device) == ERROR_NONE;
+#else
     return false;
-    }
-
-    if (!data.isStarted) {
-        LOGGER.error("({}) Stopping: Not started", static_cast<int>(port));
-        return false;
-    }
-
-#ifdef ESP_PLATFORM
-    esp_err_t result = i2c_driver_delete(port);
-    if (result != ESP_OK) {
-        LOGGER.error("({}) Stopping: Failed to delete driver: {}", static_cast<int>(port), esp_err_to_name(result));
-        return false;
-    }
-#endif // ESP_PLATFORM
-
-    data.isStarted = false;
-
-    LOGGER.info("({}) Stopped", static_cast<int>(port));
-    return true;
+#endif
 }
 
 bool isStarted(i2c_port_t port) {
+#ifdef ESP_PLATFORM
     auto lock = getLock(port).asScopedLock();
     lock.lock();
-    return dataArray[port].isStarted;
+    if (!dataArray[port].isConfigured) return false;
+    return device_is_ready(dataArray[port].device);
+#else
+    return false;
+#endif
+}
+
+const char* getName(i2c_port_t port) {
+#ifdef ESP_PLATFORM
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return nullptr;
+    return dataArray[port].device->name;
+#else
+    return nullptr;
+#endif
 }
 
 bool masterRead(i2c_port_t port, uint8_t address, uint8_t* data, size_t dataSize, TickType_t timeout) {
-    auto lock = getLock(port).asScopedLock();
-    if (!lock.lock(timeout)) {
-        LOGGER.error("({}) Mutex timeout", static_cast<int>(port));
-        return false;
-    }
-
 #ifdef ESP_PLATFORM
-    auto result = i2c_master_read_from_device(port, address, data, dataSize, timeout);
-    ESP_ERROR_CHECK_WITHOUT_ABORT(result);
-    return result == ESP_OK;
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return false;
+    return i2c_controller_read(dataArray[port].device, address, data, dataSize, timeout) == ERROR_NONE;
 #else
     return false;
-#endif // ESP_PLATFORM
+#endif
 }
 
 bool masterReadRegister(i2c_port_t port, uint8_t address, uint8_t reg, uint8_t* data, size_t dataSize, TickType_t timeout) {
-    auto lock = getLock(port).asScopedLock();
-    if (!lock.lock(timeout)) {
-        LOGGER.error("({}) Mutex timeout", static_cast<int>(port));
-        return false;
-    }
-
 #ifdef ESP_PLATFORM
-    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
-    // Set address pointer
-    i2c_master_start(cmd);
-    i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_WRITE, ACK_CHECK_EN);
-    i2c_master_write(cmd, &reg, 1, ACK_CHECK_EN);
-    // Read length of response from current pointer
-    i2c_master_start(cmd);
-    i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_READ, ACK_CHECK_EN);
-    if (dataSize > 1) {
-        i2c_master_read(cmd, data, dataSize - 1, I2C_MASTER_ACK);
-    }
-    i2c_master_read_byte(cmd, data + dataSize - 1, I2C_MASTER_NACK);
-    i2c_master_stop(cmd);
-    // TODO: We're passing an inaccurate timeout value as we already lost time with locking
-    esp_err_t result = i2c_master_cmd_begin(port, cmd, timeout);
-    i2c_cmd_link_delete(cmd);
-
-    ESP_ERROR_CHECK_WITHOUT_ABORT(result);
-
-    return result == ESP_OK;
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return false;
+    return i2c_controller_read_register(dataArray[port].device, address, reg, data, dataSize, timeout) == ERROR_NONE;
 #else
     return false;
-#endif // ESP_PLATFORM
+#endif
 }
 
 bool masterWrite(i2c_port_t port, uint8_t address, const uint8_t* data, uint16_t dataSize, TickType_t timeout) {
-    auto lock = getLock(port).asScopedLock();
-    if (!lock.lock(timeout)) {
-        LOGGER.error("({}) Mutex timeout", static_cast<int>(port));
-        return false;
-    }
-
 #ifdef ESP_PLATFORM
-    auto result = i2c_master_write_to_device(port, address, data, dataSize, timeout);
-    ESP_ERROR_CHECK_WITHOUT_ABORT(result);
-    return result == ESP_OK;
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return false;
+    return i2c_controller_write(dataArray[port].device, address, data, dataSize, timeout) == ERROR_NONE;
 #else
     return false;
-#endif // ESP_PLATFORM
+#endif
 }
 
 bool masterWriteRegister(i2c_port_t port, uint8_t address, uint8_t reg, const uint8_t* data, uint16_t dataSize, TickType_t timeout) {
-    check(reg != 0);
-
-    auto lock = getLock(port).asScopedLock();
-    if (!lock.lock(timeout)) {
-        LOGGER.error("({}) Mutex timeout", static_cast<int>(port));
-        return false;
-    }
-
 #ifdef ESP_PLATFORM
-
-    i2c_cmd_handle_t cmd = i2c_cmd_link_create();
-    i2c_master_start(cmd);
-    i2c_master_write_byte(cmd, (address << 1) | I2C_MASTER_WRITE, ACK_CHECK_EN);
-    i2c_master_write_byte(cmd, reg, ACK_CHECK_EN);
-    i2c_master_write(cmd, (uint8_t*) data, dataSize, ACK_CHECK_EN);
-    i2c_master_stop(cmd);
-    // TODO: We're passing an inaccurate timeout value as we already lost time with locking
-    esp_err_t result = i2c_master_cmd_begin(port, cmd, timeout);
-    i2c_cmd_link_delete(cmd);
-
-    ESP_ERROR_CHECK_WITHOUT_ABORT(result);
-    return result == ESP_OK;
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return false;
+    return i2c_controller_write_register(dataArray[port].device, address, reg, data, dataSize, timeout) == ERROR_NONE;
 #else
     return false;
-#endif // ESP_PLATFORM
+#endif
 }
 
 bool masterWriteRegisterArray(i2c_port_t port, uint8_t address, const uint8_t* data, uint16_t dataSize, TickType_t timeout) {
 #ifdef ESP_PLATFORM
-    assert(dataSize % 2 == 0);
-    bool result = true;
-    for (int i = 0; i < dataSize; i += 2) {
-        // TODO: We're passing an inaccurate timeout value as we already lost time with locking and previous writes in this loop
-        if (!masterWriteRegister(port, address, data[i], &data[i + 1], 1, timeout)) {
-            result = false;
-        }
-    }
-    return result;
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return false;
+    return i2c_controller_write_register_array(dataArray[port].device, address, data, dataSize, timeout) == ERROR_NONE;
 #else
     return false;
-#endif // ESP_PLATFORM
+#endif
 }
 
 bool masterWriteRead(i2c_port_t port, uint8_t address, const uint8_t* writeData, size_t writeDataSize, uint8_t* readData, size_t readDataSize, TickType_t timeout) {
-    auto lock = getLock(port).asScopedLock();
-    if (!lock.lock(timeout)) {
-        LOGGER.error("({}) Mutex timeout", static_cast<int>(port));
-        return false;
-    }
-
 #ifdef ESP_PLATFORM
-    esp_err_t result = i2c_master_write_read_device(port, address, writeData, writeDataSize, readData, readDataSize, timeout);
-    ESP_ERROR_CHECK_WITHOUT_ABORT(result);
-    return result == ESP_OK;
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return false;
+    return i2c_controller_write_read(dataArray[port].device, address, writeData, writeDataSize, readData, readDataSize, timeout) == ERROR_NONE;
 #else
     return false;
-#endif // ESP_PLATFORM
+#endif
 }
 
 bool masterHasDeviceAtAddress(i2c_port_t port, uint8_t address, TickType_t timeout) {
-    auto lock = getLock(port).asScopedLock();
-    if (!lock.lock(timeout)) {
-        LOGGER.error("({}) Mutex timeout", static_cast<int>(port));
-        return false;
-    }
-
 #ifdef ESP_PLATFORM
-    uint8_t message[2] = { 0, 0 };
-    // TODO: We're passing an inaccurate timeout value as we already lost time with locking
-    return i2c_master_write_to_device(port, address, message, 2, timeout) == ESP_OK;
+    auto lock = getLock(port).asScopedLock();
+    lock.lock();
+    if (!dataArray[port].isConfigured) return false;
+    return i2c_controller_has_device_at_address(dataArray[port].device, address, timeout) == ERROR_NONE;
 #else
     return false;
-#endif // ESP_PLATFORM
+#endif
 }
 
 Lock& getLock(i2c_port_t port) {

TactilityKernel/Bindings/i2c-controller.yaml

@@ -1,10 +1 @@
 bus: i2c
-
-properties:
-  clock-frequency:
-    type: int
-    description: Initial clock frequency in Hz
-  pin-sda:
-    type: phandle-array
-  pin-scl:
-    type: phandle-array

TactilityKernel/CMakeLists.txt

@@ -7,6 +7,8 @@ if (DEFINED ENV{ESP_IDF_VERSION})
     idf_component_register(
         SRCS ${SOURCES}
         INCLUDE_DIRS "Include/"
+        # TODO move the related logic for esp_time in Tactility/time.h into the Platform/ subproject
+        REQUIRES esp_timer
     )
 
 else ()

TactilityKernel/Include/tactility/check.h

@@ -14,7 +14,7 @@ __attribute__((noreturn)) extern void __crash(void);
 #define CHECK_NO_MSG(condition) \
     do { \
         if (!(condition)) { \
-            LOG_E("Error", "Check failed: %s at %s:%d", #condition, __FILE__, __LINE__); \
+            LOG_E("Error", "Check failed: %s\n\tat %s:%d", #condition, __FILE__, __LINE__); \
             __crash(); \
         } \
     } while (0)
@@ -22,7 +22,7 @@ __attribute__((noreturn)) extern void __crash(void);
 #define CHECK_MSG(condition, message) \
     do { \
         if (!(condition)) { \
-            LOG_E("Error", "Check failed: %s at %s:%d", message, __FILE__, __LINE__); \
+            LOG_E("Error", "Check failed: %s\n\tat %s:%d", message, __FILE__, __LINE__); \
             __crash(); \
         } \
     } while (0)

TactilityKernel/Include/tactility/concurrent/thread.h

@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include "tactility/error.h"
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef ESP_PLATFORM
+#include <esp_log.h>
+#endif
+
+#include <tactility/freertos/task.h>
+#include <tactility/concurrent/mutex.h>
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+typedef enum {
+    THREAD_STATE_STOPPED,
+    THREAD_STATE_STARTING,
+    THREAD_STATE_RUNNING,
+} ThreadState;
+
+/** ThreadPriority */
+enum ThreadPriority {
+    THREAD_PRIORITY_NONE = 0U,
+    THREAD_PRIORITY_IDLE = 1U,
+    THREAD_PRIORITY_LOWER = 2U,
+    THREAD_PRIORITY_LOW = 3U,
+    THREAD_PRIORITY_NORMAL = 4U,
+    THREAD_PRIORITY_HIGH = 5U,
+    THREAD_PRIORITY_HIGHER = 6U,
+    THREAD_PRIORITY_CRITICAL = 7U
+};
+
+typedef int32_t (*thread_main_fn_t)(void* context);
+typedef void (*thread_state_callback_t)(ThreadState state, void* context);
+
+struct Thread;
+typedef struct Thread Thread;
+
+/**
+ * @brief Creates a new thread instance with default settings.
+ * @return A pointer to the created Thread instance, or NULL if allocation failed.
+ */
+Thread* thread_alloc(void);
+
+/**
+ * @brief Creates a new thread instance with specified parameters.
+ * @param[in] name The name of the thread.
+ * @param[in] stack_size The size of the thread stack in bytes.
+ * @param[in] function The main function to be executed by the thread.
+ * @param[in] function_context A pointer to the context to be passed to the main function.
+ * @param[in] affinity The CPU core affinity for the thread (e.g., tskNO_AFFINITY).
+ * @return A pointer to the created Thread instance, or NULL if allocation failed.
+ */
+Thread* thread_alloc_full(
+    const char* name,
+    configSTACK_DEPTH_TYPE stack_size,
+    thread_main_fn_t function,
+    void* function_context,
+    portBASE_TYPE affinity
+);
+
+/**
+ * @brief Destroys a thread instance.
+ * @param[in] thread The thread instance to destroy.
+ * @note The thread must be in the STOPPED state.
+ */
+void thread_free(Thread* thread);
+
+/**
+ * @brief Sets the name of the thread.
+ * @param[in] thread The thread instance.
+ * @param[in] name The new name for the thread.
+ * @note Can only be called when the thread is in the STOPPED state.
+ */
+void thread_set_name(Thread* thread, const char* name);
+
+/**
+ * @brief Sets the stack size for the thread.
+ * @param[in] thread The thread instance.
+ * @param[in] stack_size The stack size in bytes. Must be a multiple of 4.
+ * @note Can only be called when the thread is in the STOPPED state.
+ */
+void thread_set_stack_size(Thread* thread, size_t stack_size);
+
+/**
+ * @brief Sets the CPU core affinity for the thread.
+ * @param[in] thread The thread instance.
+ * @param[in] affinity The CPU core affinity.
+ * @note Can only be called when the thread is in the STOPPED state.
+ */
+void thread_set_affinity(Thread* thread, portBASE_TYPE affinity);
+
+/**
+ * @brief Sets the main function and context for the thread.
+ * @param[in] thread The thread instance.
+ * @param[in] function The main function to be executed.
+ * @param[in] context A pointer to the context to be passed to the main function.
+ * @note Can only be called when the thread is in the STOPPED state.
+ */
+void thread_set_main_function(Thread* thread, thread_main_fn_t function, void* context);
+
+/**
+ * @brief Sets the priority for the thread.
+ * @param[in] thread The thread instance.
+ * @param[in] priority The thread priority.
+ * @note Can only be called when the thread is in the STOPPED state.
+ */
+void thread_set_priority(Thread* thread, enum ThreadPriority priority);
+
+/**
+ * @brief Sets a callback to be invoked when the thread state changes.
+ * @param[in] thread The thread instance.
+ * @param[in] callback The callback function.
+ * @param[in] context A pointer to the context to be passed to the callback function.
+ * @note Can only be called when the thread is in the STOPPED state.
+ */
+void thread_set_state_callback(Thread* thread, thread_state_callback_t callback, void* context);
+
+/**
+ * @brief Gets the current state of the thread.
+ * @param[in] thread The thread instance.
+ * @return The current ThreadState.
+ */
+ThreadState thread_get_state(Thread* thread);
+
+/**
+ * @brief Starts the thread execution.
+ * @param[in] thread The thread instance.
+ * @note The thread must be in the STOPPED state and have a main function set.
+ * @retval ERROR_NONE when the thread was started
+ * @retval ERROR_UNDEFINED when the thread failed to start
+ */
+error_t thread_start(Thread* thread);
+
+/**
+ * @brief Waits for the thread to finish execution.
+ * @param[in] thread The thread instance.
+ * @param[in] timeout The maximum time to wait in ticks.
+ * @param[in] poll_interval The interval between status checks in ticks.
+ * @retval ERROR_NONE when the thread was stopped
+ * @retval ERROR_TIMEOUT when the thread was not stopped because the timeout has passed
+ * @note Cannot be called from the thread being joined.
+ */
+error_t thread_join(Thread* thread, TickType_t timeout, TickType_t poll_interval);
+
+/**
+ * @brief Gets the FreeRTOS task handle associated with the thread.
+ * @param[in] thread The thread instance.
+ * @return The TaskHandle_t, or NULL if the thread is not running.
+ */
+TaskHandle_t thread_get_task_handle(Thread* thread);
+
+/**
+ * @brief Gets the return code from the thread's main function.
+ * @param[in] thread The thread instance.
+ * @return The return code of the thread's main function.
+ * @note The thread must be in the STOPPED state.
+ */
+int32_t thread_get_return_code(Thread* thread);
+
+/**
+ * @brief Gets the minimum remaining stack space for the thread since it started.
+ * @param[in] thread The thread instance.
+ * @return The minimum remaining stack space in bytes.
+ * @note The thread must be in the RUNNING state.
+ */
+uint32_t thread_get_stack_space(Thread* thread);
+
+/**
+ * @brief Gets the current thread instance.
+ * @return A pointer to the current Thread instance, or NULL if not called from a thread created by this module.
+ */
+Thread* thread_get_current(void);
+
+#ifdef __cplusplus
+}
+#endif

TactilityKernel/Include/tactility/concurrent/timer.h

@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: Apache-2.0
+#pragma once
+
+#include "tactility/error.h"
+#include "tactility/freertos/timers.h"
+#include "tactility/concurrent/thread.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum TimerType {
+    TIMER_TYPE_ONCE = 0,    // Timer triggers once after time has passed
+    TIMER_TYPE_PERIODIC = 1 // Timer triggers repeatedly after time has passed
+};
+
+typedef void (*timer_callback_t)(void* context);
+typedef void (*timer_pending_callback_t)(void* context, uint32_t arg);
+
+struct Timer;
+
+/**
+ * @brief Creates a new timer instance.
+ * @param[in] type The timer type.
+ * @param[in] ticks The timer period in ticks.
+ * @param[in] callback The callback function.
+ * @param[in] context The context to pass to the callback function.
+ * @return A pointer to the created timer instance, or NULL if allocation failed.
+ */
+struct Timer* timer_alloc(enum TimerType type, TickType_t ticks, timer_callback_t callback, void* context);
+
+/**
+ * @brief Destroys a timer instance.
+ * @param[in] timer The timer instance to destroy.
+ */
+void timer_free(struct Timer* timer);
+
+/**
+ * @brief Starts the timer.
+ * @param[in] timer The timer instance.
+ * @return ERROR_NONE on success, ERROR_TIMEOUT if the command queue was full.
+ */
+error_t timer_start(struct Timer* timer);
+
+/**
+ * @brief Stops the timer.
+ * @param[in] timer The timer instance.
+ * @return ERROR_NONE on success, ERROR_TIMEOUT if the command queue was full.
+ */
+error_t timer_stop(struct Timer* timer);
+
+/**
+ * @brief Set a new interval and reset the timer.
+ * @param[in] timer The timer instance.
+ * @param[in] interval The new timer interval in ticks.
+ * @return ERROR_NONE on success, ERROR_TIMEOUT if the command queue was full.
+ */
+error_t timer_reset_with_interval(struct Timer* timer, TickType_t interval);
+
+/**
+ * @brief Reset the timer.
+ * @param[in] timer The timer instance.
+ * @return ERROR_NONE on success, ERROR_TIMEOUT if the command queue was full.
+ */
+error_t timer_reset(struct Timer* timer);
+
+/**
+ * @brief Check if the timer is running.
+ * @param[in] timer The timer instance.
+ * @return true when the timer is running.
+ */
+bool timer_is_running(struct Timer* timer);
+
+/**
+ * @brief Gets the expiry time of the timer.
+ * @param[in] timer The timer instance.
+ * @return The expiry time in ticks.
+ */
+TickType_t timer_get_expiry_time(struct Timer* timer);
+
+/**
+ * @brief Calls xTimerPendFunctionCall internally.
+ * @param[in] timer The timer instance.
+ * @param[in] callback the function to call
+ * @param[in] context the first function argument
+ * @param[in] arg the second function argument
+ * @param[in] timeout the function timeout (must set to 0 in ISR mode)
+ * @return ERROR_NONE on success, ERROR_TIMEOUT if the command queue was full.
+ */
+error_t timer_set_pending_callback(struct Timer* timer, timer_pending_callback_t callback, void* context, uint32_t arg, TickType_t timeout);
+
+/**
+ * @brief Set callback priority (priority of the timer daemon task).
+ * @param[in] timer The timer instance.
+ * @param[in] priority The priority.
+ */
+void timer_set_callback_priority(struct Timer* timer, enum ThreadPriority priority);
+
+#ifdef __cplusplus
+}
+#endif

TactilityKernel/Include/tactility/defines.h

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: Apache-2.0
+/**
+ * @brief Contains various unsorted defines
+ * @note Preprocessor defines with potentially clashing names implement an #ifdef check.
+ */
+#pragma once
+
+#ifndef MIN
+/** @brief Get the minimum value of 2 values */
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
+
+#ifndef MAX
+/** @brief Get the maximum value of 2 values */
+#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+#endif
+
+#ifndef CLAMP
+/** @brief Clamp a value between the provided minimum and maximum */
+#define CLAMP(min, max, value) (((value) < (min)) ? (min) : (((value) > (max)) ? (max) : (value)))
+#endif

TactilityKernel/Include/tactility/device.h

@@ -133,6 +133,10 @@ error_t device_stop(struct Device* device);
  */
 void device_set_parent(struct Device* device, struct Device* parent);
 
+error_t device_construct_add(struct Device* device, const char* compatible);
+
+error_t device_construct_add_start(struct Device* device, const char* compatible);
+
 static inline void device_set_driver(struct Device* device, struct Driver* driver) {
     device->internal.driver = driver;
 }

TactilityKernel/Include/tactility/drivers/gpio_controller.h

@@ -10,17 +10,85 @@ extern "C" {
 #include <tactility/error.h>
 
 struct GpioControllerApi {
+    /**
+     * @brief Sets the logical level of a GPIO pin.
+     * @param[in] device the GPIO controller device
+     * @param[in] pin the pin index
+     * @param[in] high true to set the pin high, false to set it low
+     * @return ERROR_NONE if successful
+     */
     error_t (*set_level)(struct Device* device, gpio_pin_t pin, bool high);
+
+    /**
+     * @brief Gets the logical level of a GPIO pin.
+     * @param[in] device the GPIO controller device
+     * @param[in] pin the pin index
+     * @param[out] high pointer to store the pin level
+     * @return ERROR_NONE if successful
+     */
     error_t (*get_level)(struct Device* device, gpio_pin_t pin, bool* high);
+
+    /**
+     * @brief Configures the options for a GPIO pin.
+     * @param[in] device the GPIO controller device
+     * @param[in] pin the pin index
+     * @param[in] options configuration flags (direction, pull-up/down, etc.)
+     * @return ERROR_NONE if successful
+     */
     error_t (*set_options)(struct Device* device, gpio_pin_t pin, gpio_flags_t options);
+
+    /**
+     * @brief Gets the configuration options for a GPIO pin.
+     * @param[in] device the GPIO controller device
+     * @param[in] pin the pin index
+     * @param[out] options pointer to store the configuration flags
+     * @return ERROR_NONE if successful
+     */
     error_t (*get_options)(struct Device* device, gpio_pin_t pin, gpio_flags_t* options);
 };
 
+/**
+ * @brief Sets the logical level of a GPIO pin.
+ * @param[in] device the GPIO controller device
+ * @param[in] pin the pin index
+ * @param[in] high true to set the pin high, false to set it low
+ * @return ERROR_NONE if successful
+ */
 error_t gpio_controller_set_level(struct Device* device, gpio_pin_t pin, bool high);
+
+/**
+ * @brief Gets the logical level of a GPIO pin.
+ * @param[in] device the GPIO controller device
+ * @param[in] pin the pin index
+ * @param[out] high pointer to store the pin level
+ * @return ERROR_NONE if successful
+ */
 error_t gpio_controller_get_level(struct Device* device, gpio_pin_t pin, bool* high);
+
+/**
+ * @brief Configures the options for a GPIO pin.
+ * @param[in] device the GPIO controller device
+ * @param[in] pin the pin index
+ * @param[in] options configuration flags (direction, pull-up/down, etc.)
+ * @return ERROR_NONE if successful
+ */
 error_t gpio_controller_set_options(struct Device* device, gpio_pin_t pin, gpio_flags_t options);
+
+/**
+ * @brief Gets the configuration options for a GPIO pin.
+ * @param[in] device the GPIO controller device
+ * @param[in] pin the pin index
+ * @param[out] options pointer to store the configuration flags
+ * @return ERROR_NONE if successful
+ */
 error_t gpio_controller_get_options(struct Device* device, gpio_pin_t pin, gpio_flags_t* options);
 
+/**
+ * @brief Configures the options for a GPIO pin using a pin configuration structure.
+ * @param[in] device the GPIO controller device
+ * @param[in] config the pin configuration structure
+ * @return ERROR_NONE if successful
+ */
 static inline error_t gpio_set_options_config(struct Device* device, const struct GpioPinConfig* config) {
     return gpio_controller_set_options(device, config->pin, config->flags);
 }

TactilityKernel/Include/tactility/drivers/i2c_controller.h

@@ -13,18 +13,154 @@ extern "C" {
 #include <tactility/freertos/freertos.h>
 #include <tactility/error.h>
 
+/**
+ * @brief API for I2C controller drivers.
+ */
 struct I2cControllerApi {
+    /**
+     * @brief Reads data from an I2C device.
+     * @param[in] device the I2C controller device
+     * @param[in] address the 7-bit I2C address of the slave device
+     * @param[out] data the buffer to store the read data
+     * @param[in] dataSize the number of bytes to read
+     * @param[in] timeout the maximum time to wait for the operation to complete
+     * @retval ERROR_NONE when the read operation was successful
+     * @retval ERROR_TIMEOUT when the operation timed out
+     */
     error_t (*read)(struct Device* device, uint8_t address, uint8_t* data, size_t dataSize, TickType_t timeout);
+
+    /**
+     * @brief Writes data to an I2C device.
+     * @param[in] device the I2C controller device
+     * @param[in] address the 7-bit I2C address of the slave device
+     * @param[in] data the buffer containing the data to write
+     * @param[in] dataSize the number of bytes to write
+     * @param[in] timeout the maximum time to wait for the operation to complete
+     * @retval ERROR_NONE when the write operation was successful
+     * @retval ERROR_TIMEOUT when the operation timed out
+     */
     error_t (*write)(struct Device* device, uint8_t address, const uint8_t* data, uint16_t dataSize, TickType_t timeout);
+
+    /**
+     * @brief Writes data to then reads data from an I2C device.
+     * @param[in] device the I2C controller device
+     * @param[in] address the 7-bit I2C address of the slave device
+     * @param[in] writeData the buffer containing the data to write
+     * @param[in] writeDataSize the number of bytes to write
+     * @param[out] readData the buffer to store the read data
+     * @param[in] readDataSize the number of bytes to read
+     * @param[in] timeout the maximum time to wait for the operation to complete
+     * @retval ERROR_NONE when the operation was successful
+     * @retval ERROR_TIMEOUT when the operation timed out
+     */
     error_t (*write_read)(struct Device* device, uint8_t address, const uint8_t* writeData, size_t writeDataSize, uint8_t* readData, size_t readDataSize, TickType_t timeout);
+
+    /**
+     * @brief Reads data from a register of an I2C device.
+     * @param[in] device the I2C controller device
+     * @param[in] address the 7-bit I2C address of the slave device
+     * @param[in] reg the register address to read from
+     * @param[out] data the buffer to store the read data
+     * @param[in] dataSize the number of bytes to read
+     * @param[in] timeout the maximum time to wait for the operation to complete
+     * @retval ERROR_NONE when the read operation was successful
+     * @retval ERROR_TIMEOUT when the operation timed out
+     */
+    error_t (*read_register)(struct Device* device, uint8_t address, uint8_t reg, uint8_t* data, size_t dataSize, TickType_t timeout);
+
+    /**
+     * @brief Writes data to a register of an I2C device.
+     * @param[in] device the I2C controller device
+     * @param[in] address the 7-bit I2C address of the slave device
+     * @param[in] reg the register address to write to
+     * @param[in] data the buffer containing the data to write
+     * @param[in] dataSize the number of bytes to write
+     * @param[in] timeout the maximum time to wait for the operation to complete
+     * @retval ERROR_NONE when the write operation was successful
+     * @retval ERROR_TIMEOUT when the operation timed out
+     */
+    error_t (*write_register)(struct Device* device, uint8_t address, uint8_t reg, const uint8_t* data, uint16_t dataSize, TickType_t timeout);
 };
 
+/**
+ * @brief Reads data from an I2C device using the specified controller.
+ * @param[in] device the I2C controller device
+ * @param[in] address the 7-bit I2C address of the slave device
+ * @param[out] data the buffer to store the read data
+ * @param[in] dataSize the number of bytes to read
+ * @param[in] timeout the maximum time to wait for the operation to complete
+ * @retval ERROR_NONE when the read operation was successful
+ */
 error_t i2c_controller_read(struct Device* device, uint8_t address, uint8_t* data, size_t dataSize, TickType_t timeout);
 
+/**
+ * @brief Writes data to an I2C device using the specified controller.
+ * @param[in] device the I2C controller device
+ * @param[in] address the 7-bit I2C address of the slave device
+ * @param[in] data the buffer containing the data to write
+ * @param[in] dataSize the number of bytes to write
+ * @param[in] timeout the maximum time to wait for the operation to complete
+ * @retval ERROR_NONE when the write operation was successful
+ */
 error_t i2c_controller_write(struct Device* device, uint8_t address, const uint8_t* data, uint16_t dataSize, TickType_t timeout);
 
+/**
+ * @brief Writes data to then reads data from an I2C device using the specified controller.
+ * @param[in] device the I2C controller device
+ * @param[in] address the 7-bit I2C address of the slave device
+ * @param[in] writeData the buffer containing the data to write
+ * @param[in] writeDataSize the number of bytes to write
+ * @param[out] readData the buffer to store the read data
+ * @param[in] readDataSize the number of bytes to read
+ * @param[in] timeout the maximum time to wait for the operation to complete
+ * @retval ERROR_NONE when the operation was successful
+ */
 error_t i2c_controller_write_read(struct Device* device, uint8_t address, const uint8_t* writeData, size_t writeDataSize, uint8_t* readData, size_t readDataSize, TickType_t timeout);
 
+/**
+ * @brief Reads data from a register of an I2C device using the specified controller.
+ * @param[in] device the I2C controller device
+ * @param[in] address the 7-bit I2C address of the slave device
+ * @param[in] reg the register address to read from
+ * @param[out] data the buffer to store the read data
+ * @param[in] dataSize the number of bytes to read
+ * @param[in] timeout the maximum time to wait for the operation to complete
+ * @retval ERROR_NONE when the read operation was successful
+ */
+error_t i2c_controller_read_register(struct Device* device, uint8_t address, uint8_t reg, uint8_t* data, size_t dataSize, TickType_t timeout);
+
+/**
+ * @brief Writes data to a register of an I2C device using the specified controller.
+ * @param[in] device the I2C controller device
+ * @param[in] address the 7-bit I2C address of the slave device
+ * @param[in] reg the register address to write to
+ * @param[in] data the buffer containing the data to write
+ * @param[in] dataSize the number of bytes to write
+ * @param[in] timeout the maximum time to wait for the operation to complete
+ * @retval ERROR_NONE when the write operation was successful
+ */
+error_t i2c_controller_write_register(struct Device* device, uint8_t address, uint8_t reg, const uint8_t* data, uint16_t dataSize, TickType_t timeout);
+
+/**
+ * @brief Writes an array of register-value pairs to an I2C device.
+ * @param[in] device the I2C controller device
+ * @param[in] address the 7-bit I2C address of the slave device
+ * @param[in] data an array of bytes where even indices are register addresses and odd indices are values
+ * @param[in] dataSize the number of bytes in the data array (must be even)
+ * @param[in] timeout the maximum time to wait for each operation to complete
+ * @retval ERROR_NONE when all write operations were successful
+ */
+error_t i2c_controller_write_register_array(struct Device* device, uint8_t address, const uint8_t* data, uint16_t dataSize, TickType_t timeout);
+
+/**
+ * @brief Checks if an I2C device is present at the specified address.
+ * @param[in] device the I2C controller device
+ * @param[in] address the 7-bit I2C address to check
+ * @param[in] timeout the maximum time to wait for the check to complete
+ * @retval ERROR_NONE when a device responded at the address
+ */
+error_t i2c_controller_has_device_at_address(struct Device* device, uint8_t address, TickType_t timeout);
+
 extern const struct DeviceType I2C_CONTROLLER_TYPE;
 
 #ifdef __cplusplus

TactilityKernel/Include/tactility/error.h

@@ -2,6 +2,10 @@
 
 #pragma once
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 // Avoid potential clash with bits/types/error_t.h
 #ifndef __error_t_defined
 typedef int error_t;
@@ -17,3 +21,11 @@ typedef int error_t;
 #define ERROR_RESOURCE 7 // A problem with a resource/dependency
 #define ERROR_TIMEOUT 8
 #define ERROR_OUT_OF_MEMORY 9
+#define ERROR_NOT_SUPPORTED 10
+
+/** Convert an error_t to a human-readable text. Useful for logging. */
+const char* error_to_string(error_t error);
+
+#ifdef __cplusplus
+}
+#endif

TactilityKernel/Include/tactility/time.h

@@ -1,7 +1,13 @@
+// SPDX-License-Identifier: Apache-2.0
+/**
+ * Time-keeping related functionality.
+ * This includes functionality for both ticks and seconds.
+ */
 #pragma once
 
 #include <stdint.h>
 
+#include "defines.h"
 #include "tactility/freertos/task.h"
 
 #ifdef ESP_PLATFORM
@@ -32,6 +38,14 @@ static inline size_t get_millis() {
     return get_ticks() * portTICK_PERIOD_MS;
 }
 
+static inline TickType_t get_timeout_remaining_ticks(TickType_t timeout, TickType_t start_time) {
+    TickType_t ticks_passed = get_ticks() - start_time;
+    if (ticks_passed >= timeout) {
+        return 0;
+    }
+    return timeout - ticks_passed;
+}
+
 /** @return the frequency at which the kernel task schedulers operate */
 uint32_t kernel_get_tick_frequency();
 

TactilityKernel/Source/concurrent/dispatcher.cpp

@@ -11,7 +11,7 @@
 #include <tactility/log.h>
 #include <atomic>
 
-#define TAG LOG_TAG("Dispatcher")
+#define TAG LOG_TAG(Dispatcher)
 
 static constexpr EventBits_t BACKPRESSURE_WARNING_COUNT = 100U;
 static constexpr EventBits_t WAIT_FLAG = 1U;

TactilityKernel/Source/concurrent/thread.cpp

@@ -0,0 +1,278 @@
+// SPDX-License-Identifier: Apache-2.0
+#include <tactility/concurrent/thread.h>
+#include <tactility/concurrent/mutex.h>
+#include <tactility/check.h>
+#include <tactility/delay.h>
+#include <tactility/log.h>
+#include <tactility/time.h>
+
+#include <cstdlib>
+#include <cstring>
+#include <string>
+
+static const size_t LOCAL_STORAGE_SELF_POINTER_INDEX = 0;
+static const char* TAG = LOG_TAG(Thread);
+
+struct Thread {
+    TaskHandle_t taskHandle = nullptr;
+    ThreadState state = THREAD_STATE_STOPPED;
+    thread_main_fn_t mainFunction = nullptr;
+    void* mainFunctionContext = nullptr;
+    int32_t callbackResult = 0;
+    thread_state_callback_t stateCallback = nullptr;
+    void* stateCallbackContext = nullptr;
+    std::string name = "unnamed";
+    enum ThreadPriority priority = THREAD_PRIORITY_NORMAL;
+    struct Mutex mutex = { 0 };
+    configSTACK_DEPTH_TYPE stackSize = 4096;
+    portBASE_TYPE affinity = -1;
+
+    Thread() {
+        mutex_construct(&mutex);
+    }
+
+    ~Thread() {
+        mutex_destruct(&mutex);
+    }
+
+    void lock() { mutex_lock(&mutex); }
+
+    void unlock() { mutex_unlock(&mutex); }
+};
+
+static void thread_set_state_internal(Thread* thread, ThreadState newState) {
+    thread->lock();
+    thread->state = newState;
+    auto cb = thread->stateCallback;
+    auto cb_ctx = thread->stateCallbackContext;
+    thread->unlock();
+    if (cb) {
+        cb(newState, cb_ctx);
+    }
+}
+
+static void thread_main_body(void* context) {
+    check(context != nullptr);
+    auto* thread = static_cast<Thread*>(context);
+
+    // Save Thread instance pointer to task local storage
+    check(pvTaskGetThreadLocalStoragePointer(nullptr, LOCAL_STORAGE_SELF_POINTER_INDEX) == nullptr);
+    vTaskSetThreadLocalStoragePointer(nullptr, LOCAL_STORAGE_SELF_POINTER_INDEX, thread);
+
+    LOG_I(TAG, "Starting %s", thread->name.c_str()); // No need to lock as we don't allow mutation after thread start
+    check(thread->state == THREAD_STATE_STARTING);
+    thread_set_state_internal(thread, THREAD_STATE_RUNNING);
+
+    int32_t result = thread->mainFunction(thread->mainFunctionContext);
+    thread->lock();
+    thread->callbackResult = result;
+    thread->unlock();
+
+    check(thread->state == THREAD_STATE_RUNNING);
+    thread_set_state_internal(thread, THREAD_STATE_STOPPED);
+    LOG_I(TAG, "Stopped %s", thread->name.c_str()); // No need to lock as we don't allow mutation after thread start
+
+    vTaskSetThreadLocalStoragePointer(nullptr, LOCAL_STORAGE_SELF_POINTER_INDEX, nullptr);
+
+    thread->lock();
+    thread->taskHandle = nullptr;
+    thread->unlock();
+
+    vTaskDelete(nullptr);
+}
+
+extern "C" {
+
+Thread* thread_alloc(void) {
+    auto* thread = new(std::nothrow) Thread();
+    if (thread == nullptr) {
+        return nullptr;
+    }
+    return thread;
+}
+
+Thread* thread_alloc_full(
+    const char* name,
+    configSTACK_DEPTH_TYPE stack_size,
+    thread_main_fn_t function,
+    void* function_context,
+    portBASE_TYPE affinity
+) {
+    auto* thread = new(std::nothrow) Thread();
+    if (thread != nullptr) {
+        thread_set_name(thread, name);
+        thread_set_stack_size(thread, stack_size);
+        thread_set_main_function(thread, function, function_context);
+        thread_set_affinity(thread, affinity);
+    }
+    return thread;
+}
+
+void thread_free(Thread* thread) {
+    check(thread);
+    check(thread->state == THREAD_STATE_STOPPED);
+    check(thread->taskHandle == nullptr);
+    delete thread;
+}
+
+void thread_set_name(Thread* thread, const char* name) {
+    check(name != nullptr);
+    thread->lock();
+    check(thread->state == THREAD_STATE_STOPPED);
+    thread->name = name;
+    thread->unlock();
+}
+
+void thread_set_stack_size(Thread* thread, size_t stack_size) {
+    thread->lock();
+    check(stack_size > 0);
+    check(thread->state == THREAD_STATE_STOPPED);
+    thread->stackSize = stack_size;
+    thread->unlock();
+}
+
+void thread_set_affinity(Thread* thread, portBASE_TYPE affinity) {
+    thread->lock();
+    check(thread->state == THREAD_STATE_STOPPED);
+    thread->affinity = affinity;
+    thread->unlock();
+}
+
+void thread_set_main_function(Thread* thread, thread_main_fn_t function, void* context) {
+    thread->lock();
+    check(function != nullptr);
+    check(thread->state == THREAD_STATE_STOPPED);
+    thread->mainFunction = function;
+    thread->mainFunctionContext = context;
+    thread->unlock();
+}
+
+void thread_set_priority(Thread* thread, enum ThreadPriority priority) {
+    thread->lock();
+    check(thread->state == THREAD_STATE_STOPPED);
+    thread->priority = priority;
+    thread->unlock();
+}
+
+void thread_set_state_callback(Thread* thread, thread_state_callback_t callback, void* context) {
+    thread->lock();
+    check(callback != nullptr);
+    check(thread->state == THREAD_STATE_STOPPED);
+    thread->stateCallback = callback;
+    thread->stateCallbackContext = context;
+    thread->unlock();
+}
+
+ThreadState thread_get_state(Thread* thread) {
+    check(xPortInIsrContext() == pdFALSE);
+    thread->lock();
+    ThreadState state = thread->state;
+    thread->unlock();
+    return state;
+}
+
+error_t thread_start(Thread* thread) {
+    thread->lock();
+    check(thread->mainFunction != nullptr);
+    check(thread->state == THREAD_STATE_STOPPED);
+    check(thread->stackSize);
+    thread->unlock();
+
+    thread_set_state_internal(thread, THREAD_STATE_STARTING);
+
+    thread->lock();
+    uint32_t stack_depth = thread->stackSize / sizeof(StackType_t);
+    enum ThreadPriority priority = thread->priority;
+    portBASE_TYPE affinity = thread->affinity;
+    thread->unlock();
+
+    BaseType_t result;
+    if (affinity != -1) {
+#ifdef ESP_PLATFORM
+        result = xTaskCreatePinnedToCore(
+            thread_main_body,
+            thread->name.c_str(),
+            stack_depth,
+            thread,
+            (UBaseType_t)priority,
+            &thread->taskHandle,
+            affinity
+        );
+#else
+        result = xTaskCreate(
+            thread_main_body,
+            thread->name.c_str(),
+            stack_depth,
+            thread,
+            (UBaseType_t)priority,
+            &thread->taskHandle
+        );
+#endif
+    } else {
+        result = xTaskCreate(
+            thread_main_body,
+            thread->name.c_str(),
+            stack_depth,
+            thread,
+            (UBaseType_t)priority,
+            &thread->taskHandle
+        );
+    }
+
+    if (result != pdPASS) {
+        thread_set_state_internal(thread, THREAD_STATE_STOPPED);
+        thread->lock();
+        thread->taskHandle = nullptr;
+        thread->unlock();
+        return ERROR_UNDEFINED;
+    }
+
+    return ERROR_NONE;
+}
+
+error_t thread_join(Thread* thread, TickType_t timeout, TickType_t poll_interval) {
+    check(thread_get_current() != thread);
+
+    TickType_t start_ticks = get_ticks();
+    while (thread_get_task_handle(thread)) {
+        delay_ticks(poll_interval);
+        if (get_ticks() - start_ticks > timeout) {
+            return ERROR_TIMEOUT;
+        }
+    }
+
+    return ERROR_NONE;
+}
+
+TaskHandle_t thread_get_task_handle(Thread* thread) {
+    thread->lock();
+    auto* handle = thread->taskHandle;
+    thread->unlock();
+    return handle;
+}
+
+int32_t thread_get_return_code(Thread* thread) {
+    thread->lock();
+    check(thread->state == THREAD_STATE_STOPPED);
+    auto result = thread->callbackResult;
+    thread->unlock();
+    return result;
+}
+
+uint32_t thread_get_stack_space(Thread* thread) {
+    if (xPortInIsrContext() == pdTRUE) {
+        return 0;
+    }
+    thread->lock();
+    check(thread->state == THREAD_STATE_RUNNING);
+    auto result = uxTaskGetStackHighWaterMark(thread->taskHandle) * sizeof(StackType_t);
+    thread->unlock();
+    return result;
+}
+
+Thread* thread_get_current(void) {
+    check(xPortInIsrContext() == pdFALSE);
+    return (Thread*)pvTaskGetThreadLocalStoragePointer(nullptr, LOCAL_STORAGE_SELF_POINTER_INDEX);
+}
+
+}

TactilityKernel/Source/concurrent/timer.c

@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: Apache-2.0
+#include <tactility/concurrent/timer.h>
+#include <tactility/check.h>
+#include <tactility/freertos/timers.h>
+#include <stdlib.h>
+
+struct Timer {
+    TimerHandle_t handle;
+    timer_callback_t callback;
+    void* context;
+};
+
+static void timer_callback_internal(TimerHandle_t xTimer) {
+    struct Timer* timer = (struct Timer*)pvTimerGetTimerID(xTimer);
+    if (timer != NULL && timer->callback != NULL) {
+        timer->callback(timer->context);
+    }
+}
+
+struct Timer* timer_alloc(enum TimerType type, TickType_t ticks, timer_callback_t callback, void* context) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(callback != NULL);
+
+    struct Timer* timer = (struct Timer*)malloc(sizeof(struct Timer));
+    if (timer == NULL) {
+        return NULL;
+    }
+
+    timer->callback = callback;
+    timer->context = context;
+
+    BaseType_t auto_reload = (type == TIMER_TYPE_ONCE) ? pdFALSE : pdTRUE;
+    timer->handle = xTimerCreate(NULL, ticks, auto_reload, timer, timer_callback_internal);
+
+    if (timer->handle == NULL) {
+        free(timer);
+        return NULL;
+    }
+
+    return timer;
+}
+
+void timer_free(struct Timer* timer) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(timer != NULL);
+    // MAX_TICKS or a reasonable timeout for the timer command queue
+    xTimerDelete(timer->handle, portMAX_DELAY);
+    free(timer);
+}
+
+error_t timer_start(struct Timer* timer) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(timer != NULL);
+    return (xTimerStart(timer->handle, portMAX_DELAY) == pdPASS) ? ERROR_NONE : ERROR_TIMEOUT;
+}
+
+error_t timer_stop(struct Timer* timer) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(timer != NULL);
+    return (xTimerStop(timer->handle, portMAX_DELAY) == pdPASS) ? ERROR_NONE : ERROR_TIMEOUT;
+}
+
+error_t timer_reset_with_interval(struct Timer* timer, TickType_t interval) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(timer != NULL);
+    if (xTimerChangePeriod(timer->handle, interval, portMAX_DELAY) != pdPASS) {
+        return ERROR_TIMEOUT;
+    }
+    return (xTimerReset(timer->handle, portMAX_DELAY) == pdPASS) ? ERROR_NONE : ERROR_TIMEOUT;
+}
+
+error_t timer_reset(struct Timer* timer) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(timer != NULL);
+    return (xTimerReset(timer->handle, portMAX_DELAY) == pdPASS) ? ERROR_NONE : ERROR_TIMEOUT;
+}
+
+bool timer_is_running(struct Timer* timer) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(timer != NULL);
+    return xTimerIsTimerActive(timer->handle) != pdFALSE;
+}
+
+TickType_t timer_get_expiry_time(struct Timer* timer) {
+    check(xPortInIsrContext() == pdFALSE);
+    check(timer != NULL);
+    return xTimerGetExpiryTime(timer->handle);
+}
+
+error_t timer_set_pending_callback(struct Timer* timer, timer_pending_callback_t callback, void* context, uint32_t arg, TickType_t timeout) {
+    (void)timer; // Unused in this implementation but kept for API consistency if needed later
+    BaseType_t result;
+    if (xPortInIsrContext() == pdTRUE) {
+        check(timeout == 0);
+        result = xTimerPendFunctionCallFromISR(callback, context, arg, NULL);
+    } else {
+        result = xTimerPendFunctionCall(callback, context, arg, timeout);
+    }
+    return (result == pdPASS) ? ERROR_NONE : ERROR_TIMEOUT;
+}
+
+void timer_set_callback_priority(struct Timer* timer, enum ThreadPriority priority) {
+    (void)timer; // Unused in this implementation but kept for API consistency if needed later
+    check(xPortInIsrContext() == pdFALSE);
+
+    TaskHandle_t task_handle = xTimerGetTimerDaemonTaskHandle();
+    check(task_handle != NULL);
+
+    vTaskPrioritySet(task_handle, (UBaseType_t)priority);
+}

TactilityKernel/Source/crash.cpp

@@ -1,7 +1,7 @@
 #include <tactility/freertos/task.h>
 #include <tactility/log.h>
 
-static const auto* TAG = LOG_TAG("Kernel");
+static const auto* TAG = LOG_TAG(Kernel);
 
 static void log_memory_info() {
 #ifdef ESP_PLATFORM

TactilityKernel/Source/device.cpp

@@ -146,6 +146,7 @@ failed_ledger_lookup:
 }
 
 error_t device_start(Device* device) {
+    LOG_I(TAG, "start %s", device->name);
     if (!device->internal.state.added) {
         return ERROR_INVALID_STATE;
     }
@@ -166,6 +167,7 @@ error_t device_start(Device* device) {
 }
 
 error_t device_stop(struct Device* device) {
+    LOG_I(TAG, "stop %s", device->name);
     if (!device->internal.state.added) {
         return ERROR_INVALID_STATE;
     }
@@ -183,6 +185,56 @@ error_t device_stop(struct Device* device) {
     return ERROR_NONE;
 }
 
+error_t device_construct_add(struct Device* device, const char* compatible) {
+    struct Driver* driver = driver_find_compatible(compatible);
+    if (driver == nullptr) {
+        LOG_E(TAG, "Can't find driver '%s' for device '%s'", compatible, device->name);
+        return ERROR_RESOURCE;
+    }
+
+    error_t error = device_construct(device);
+    if (error != ERROR_NONE) {
+        LOG_E(TAG, "Failed to construct device %s: %s", device->name, error_to_string(error));
+        goto on_construct_error;
+    }
+
+    device_set_driver(device, driver);
+
+    error = device_add(device);
+    if (error != ERROR_NONE) {
+        LOG_E(TAG, "Failed to add device %s: %s", device->name, error_to_string(error));
+        goto on_add_error;
+    }
+
+    return ERROR_NONE;
+
+    on_add_error:
+    device_destruct(device);
+    on_construct_error:
+    return error;
+}
+
+error_t device_construct_add_start(struct Device* device, const char* compatible) {
+    error_t error = device_construct_add(device, compatible);
+    if (error != ERROR_NONE) {
+        goto on_construct_add_error;
+    }
+
+    error = device_start(device);
+    if (error != ERROR_NONE) {
+        LOG_E(TAG, "Failed to start device %s: %s", device->name, error_to_string(error));
+        goto on_start_error;
+    }
+
+    return ERROR_NONE;
+
+on_start_error:
+    device_remove(device);
+    device_destruct(device);
+on_construct_add_error:
+    return error;
+}
+
 void device_set_parent(Device* device, Device* parent) {
     assert(!device->internal.state.started);
     device->parent = parent;

TactilityKernel/Source/drivers/i2c_controller.cpp

@@ -1,6 +1,4 @@
 // SPDX-License-Identifier: Apache-2.0
-
-#include <tactility/driver.h>
 #include <tactility/drivers/i2c_controller.h>
 #include <tactility/error.h>
 
@@ -23,6 +21,34 @@ error_t i2c_controller_write_read(Device* device, uint8_t address, const uint8_t
     return I2C_DRIVER_API(driver)->write_read(device, address, writeData, writeDataSize, readData, readDataSize, timeout);
 }
 
+error_t i2c_controller_read_register(Device* device, uint8_t address, uint8_t reg, uint8_t* data, size_t dataSize, TickType_t timeout) {
+    const auto* driver = device_get_driver(device);
+    return I2C_DRIVER_API(driver)->read_register(device, address, reg, data, dataSize, timeout);
+}
+
+error_t i2c_controller_write_register(Device* device, uint8_t address, uint8_t reg, const uint8_t* data, uint16_t dataSize, TickType_t timeout) {
+    const auto* driver = device_get_driver(device);
+    return I2C_DRIVER_API(driver)->write_register(device, address, reg, data, dataSize, timeout);
+}
+
+error_t i2c_controller_write_register_array(Device* device, uint8_t address, const uint8_t* data, uint16_t dataSize, TickType_t timeout) {
+    const auto* driver = device_get_driver(device);
+    if (dataSize % 2 != 0) {
+        return ERROR_INVALID_ARGUMENT;
+    }
+    for (int i = 0; i < dataSize; i += 2) {
+        error_t error = I2C_DRIVER_API(driver)->write_register(device, address, data[i], &data[i + 1], 1, timeout);
+        if (error != ERROR_NONE) return error;
+    }
+    return ERROR_NONE;
+}
+
+error_t i2c_controller_has_device_at_address(Device* device, uint8_t address, TickType_t timeout) {
+    const auto* driver = device_get_driver(device);
+    uint8_t message[2] = { 0, 0 };
+    return I2C_DRIVER_API(driver)->write(device, address, message, 2, timeout);
+}
+
 const struct DeviceType I2C_CONTROLLER_TYPE { 0 };
 
 }

TactilityKernel/Source/error.cpp

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: Apache-2.0
+#include <tactility/error.h>
+
+extern "C" {
+
+const char* error_to_string(error_t error) {
+    switch (error) {
+        case ERROR_NONE:
+            return "no error";
+        case ERROR_UNDEFINED:
+            return "undefined";
+        case ERROR_INVALID_STATE:
+            return "invalid state";
+        case ERROR_INVALID_ARGUMENT:
+            return "invalid argument";
+        case ERROR_MISSING_PARAMETER:
+            return "missing parameter";
+        case ERROR_NOT_FOUND:
+            return "not found";
+        case ERROR_ISR_STATUS:
+            return "ISR status";
+        case ERROR_RESOURCE:
+            return "resource";
+        case ERROR_TIMEOUT:
+            return "timeout";
+        case ERROR_OUT_OF_MEMORY:
+            return "out of memory";
+        case ERROR_NOT_SUPPORTED:
+            return "not supported";
+        default:
+            return "unknown";
+    }
+}
+
+}

Tests/TactilityKernel/ThreadTest.cpp

@@ -0,0 +1,112 @@
+#include "doctest.h"
+
+#include <tactility/delay.h>
+#include <tactility/concurrent/thread.h>
+
+TEST_CASE("when a thread is started then its callback should be called") {
+    bool has_called = false;
+    auto* thread = thread_alloc_full(
+        "immediate return task",
+        4096,
+        [](void* context) {
+            auto* has_called_ptr = static_cast<bool*>(context);
+            *has_called_ptr = true;
+            return 0;
+        },
+        &has_called,
+        -1
+    );
+
+    CHECK(!has_called);
+    CHECK_EQ(thread_start(thread), ERROR_NONE);
+    CHECK_EQ(thread_join(thread, 2, 1), ERROR_NONE);
+    thread_free(thread);
+    CHECK(has_called);
+}
+
+TEST_CASE("a thread can be started and stopped") {
+    bool interrupted = false;
+    auto* thread = thread_alloc_full(
+        "interruptable thread",
+        4096,
+        [](void* context) {
+            auto* interrupted_ptr = static_cast<bool*>(context);
+            while (!*interrupted_ptr) {
+                delay_millis(1);
+            }
+            return 0;
+        },
+        &interrupted,
+        -1
+    );
+
+    CHECK(thread);
+    CHECK_EQ(thread_start(thread), ERROR_NONE);
+    interrupted = true;
+    CHECK_EQ(thread_join(thread, 2, 1), ERROR_NONE);
+    thread_free(thread);
+}
+
+TEST_CASE("thread id should only be set at when thread is started") {
+    bool interrupted = false;
+    auto* thread = thread_alloc_full(
+        "interruptable thread",
+        4096,
+        [](void* context) {
+          auto* interrupted_ptr = static_cast<bool*>(context);
+          while (!*interrupted_ptr) {
+              delay_millis(1);
+          }
+          return 0;
+        },
+        &interrupted,
+        -1
+    );
+    CHECK_EQ(thread_get_task_handle(thread), nullptr);
+    CHECK_EQ(thread_start(thread), ERROR_NONE);
+    CHECK_NE(thread_get_task_handle(thread), nullptr);
+    interrupted = true;
+    CHECK_EQ(thread_join(thread, 2, 1), ERROR_NONE);
+    CHECK_EQ(thread_get_task_handle(thread), nullptr);
+    thread_free(thread);
+}
+
+TEST_CASE("thread state should be correct") {
+    bool interrupted = false;
+    auto* thread = thread_alloc_full(
+        "interruptable thread",
+        4096,
+        [](void* context) {
+          auto* interrupted_ptr = static_cast<bool*>(context);
+          while (!*interrupted_ptr) {
+              delay_millis(1);
+          }
+          return 0;
+        },
+        &interrupted,
+        -1
+
+    );
+    CHECK_EQ(thread_get_state(thread), THREAD_STATE_STOPPED);
+    thread_start(thread);
+    auto state = thread_get_state(thread);
+    CHECK((state == THREAD_STATE_STARTING || state == THREAD_STATE_RUNNING));
+    interrupted = true;
+    CHECK_EQ(thread_join(thread, 10, 1), ERROR_NONE);
+    CHECK_EQ(thread_get_state(thread), THREAD_STATE_STOPPED);
+    thread_free(thread);
+}
+
+TEST_CASE("thread id should only be set at when thread is started") {
+    auto* thread = thread_alloc_full(
+        "return code",
+        4096,
+        [](void* context) { return 123; },
+        nullptr,
+        -1
+    );
+    CHECK_EQ(thread_start(thread), ERROR_NONE);
+    CHECK_EQ(thread_join(thread, 1, 1), ERROR_NONE);
+    CHECK_EQ(thread_get_return_code(thread), 123);
+    thread_free(thread);
+}

Tests/TactilityKernel/TimerTest.cpp

@@ -0,0 +1,147 @@
+#include "doctest.h"
+
+#include <atomic>
+
+#include <tactility/concurrent/timer.h>
+#include <tactility/delay.h>
+
+TEST_CASE("timer_alloc and timer_free should handle allocation and deallocation") {
+    auto callback = [](void* context) {};
+    struct Timer* timer = timer_alloc(TIMER_TYPE_ONCE, 10, callback, nullptr);
+    CHECK_NE(timer, nullptr);
+    timer_free(timer);
+}
+
+TEST_CASE("timer_start and timer_stop should change running state") {
+    auto callback = [](void* context) {};
+    struct Timer* timer = timer_alloc(TIMER_TYPE_ONCE, 10, callback, nullptr);
+    REQUIRE_NE(timer, nullptr);
+
+    CHECK_EQ(timer_is_running(timer), false);
+    CHECK_EQ(timer_start(timer), ERROR_NONE);
+    CHECK_EQ(timer_is_running(timer), true);
+    CHECK_EQ(timer_stop(timer), ERROR_NONE);
+    CHECK_EQ(timer_is_running(timer), false);
+
+    timer_free(timer);
+}
+
+TEST_CASE("one-shot timer should fire callback once") {
+    std::atomic<int> call_count{0};
+    struct Timer* timer = timer_alloc(TIMER_TYPE_ONCE, 10, [](void* context) {
+        auto* count = static_cast<std::atomic<int>*>(context);
+        (*count)++;
+    }, &call_count);
+    REQUIRE_NE(timer, nullptr);
+
+    CHECK_EQ(timer_start(timer), ERROR_NONE);
+    delay_millis(20);
+    
+    CHECK_EQ(call_count.load(), 1);
+    CHECK_EQ(timer_is_running(timer), false);
+
+    timer_free(timer);
+}
+
+TEST_CASE("periodic timer should fire callback multiple times") {
+    std::atomic<int> call_count{0};
+    struct Timer* timer = timer_alloc(TIMER_TYPE_PERIODIC, 10, [](void* context) {
+        auto* count = static_cast<std::atomic<int>*>(context);
+        (*count)++;
+    }, &call_count);
+    REQUIRE_NE(timer, nullptr);
+
+    CHECK_EQ(timer_start(timer), ERROR_NONE);
+    delay_millis(35); // Should fire around 3 times
+    
+    CHECK_GE(call_count.load(), 3);
+    CHECK_EQ(timer_is_running(timer), true);
+
+    timer_stop(timer);
+    timer_free(timer);
+}
+
+TEST_CASE("timer_reset should restart the timer") {
+    std::atomic<int> call_count{0};
+    struct Timer* timer = timer_alloc(TIMER_TYPE_ONCE, 20, [](void* context) {
+        auto* count = static_cast<std::atomic<int>*>(context);
+        (*count)++;
+    }, &call_count);
+    REQUIRE_NE(timer, nullptr);
+
+    CHECK_EQ(timer_start(timer), ERROR_NONE);
+    delay_millis(10);
+    CHECK_EQ(call_count.load(), 0);
+    
+    // Resetting should push the expiry further
+    CHECK_EQ(timer_reset(timer), ERROR_NONE);
+    delay_millis(15);
+    CHECK_EQ(call_count.load(), 0); // Still shouldn't have fired if reset worked
+    
+    delay_millis(10);
+    CHECK_EQ(call_count.load(), 1); // Now it should have fired
+
+    timer_free(timer);
+}
+
+TEST_CASE("timer_reset_with_interval should change the period") {
+    std::atomic<int> call_count{0};
+    struct Timer* timer = timer_alloc(TIMER_TYPE_ONCE, 40, [](void* context) {
+        auto* count = static_cast<std::atomic<int>*>(context);
+        (*count)++;
+    }, &call_count);
+    REQUIRE_NE(timer, nullptr);
+
+    CHECK_EQ(timer_start(timer), ERROR_NONE);
+    // Change to a much shorter interval
+    CHECK_EQ(timer_reset_with_interval(timer, 10), ERROR_NONE);
+    
+    delay_millis(20);
+    CHECK_EQ(call_count.load(), 1);
+
+    timer_free(timer);
+}
+
+TEST_CASE("timer_get_expiry_time should return a valid time") {
+    struct Timer* timer = timer_alloc(TIMER_TYPE_ONCE, 10, [](void* context) {}, nullptr);
+    REQUIRE_NE(timer, nullptr);
+
+    timer_start(timer);
+    TickType_t expiry = timer_get_expiry_time(timer);
+    // Expiry should be in the future
+    CHECK_GT(expiry, xTaskGetTickCount());
+
+    timer_free(timer);
+}
+
+TEST_CASE("timer_set_pending_callback should execute callback in timer task") {
+    std::atomic<bool> called{false};
+    struct Context {
+        std::atomic<bool>* called;
+        uint32_t expected_arg;
+        uint32_t received_arg;
+    } context = { &called, 0x12345678, 0 };
+
+    auto pending_cb = [](void* ctx, uint32_t arg) {
+        auto* c = static_cast<Context*>(ctx);
+        c->received_arg = arg;
+        c->called->store(true);
+    };
+
+    // timer_set_pending_callback doesn't actually use the timer object in current implementation
+    // but we need one for the API
+    struct Timer* timer = timer_alloc(TIMER_TYPE_ONCE, 10, [](void* context) {}, nullptr);
+    
+    CHECK_EQ(timer_set_pending_callback(timer, pending_cb, &context, context.expected_arg, portMAX_DELAY), ERROR_NONE);
+    
+    // Wait for timer task to process the callback
+    int retries = 10;
+    while (!called.load() && retries-- > 0) {
+        delay_millis(10);
+    }
+
+    CHECK(called.load());
+    CHECK_EQ(context.received_arg, context.expected_arg);
+
+    timer_free(timer);
+}