diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9ab5c51..123d1f7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1 +1,6 @@
-idf_component_register(SRCS "main.c" INCLUDE_DIRS "include")
\ No newline at end of file
+if(${IDF_TARGET} STREQUAL esp8266)
+    set(requires driver zh_vector)
+else()
+    set(requires driver esp_event zh_vector)
+endif()
+idf_component_register(SRCS "zh_pcf8574.c" INCLUDE_DIRS "include" REQUIRES ${requires})
\ No newline at end of file
diff --git a/README.md b/README.md
index 3df3e4d..35de209 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,138 @@
-# esp_component_template
+# ESP32 ESP-IDF and ESP8266 RTOS SDK component for PCF8574(A) 8-bit I/O expander
 
-esp_component_template
\ No newline at end of file
+## Tested on
+
+1. [ESP8266 RTOS_SDK v3.4](https://docs.espressif.com/projects/esp8266-rtos-sdk/en/latest/index.html#)
+2. [ESP32 ESP-IDF v5.4](https://docs.espressif.com/projects/esp-idf/en/release-v5.4/esp32/index.html)
+
+## Features
+
+1. Support of 16 expanders on one bus.
+2. Support of output and input GPIO's work mode.
+3. Support of interrupts from input GPIO's.
+
+## Note
+
+1. Enable interrupt support only if input GPIO's are used.
+2. All the INT GPIO's on the extenders must be connected to the one GPIO on ESP.
+3. The input GPIO's are always pullup to the power supply. They must be connected to ground to trigger an interrupt.
+
+## Dependencies
+
+1. [zh_vector](http://git.zh.com.ru/alexey.zholtikov/zh_vector)
+
+## Using
+
+In an existing project, run the following command to install the components:
+
+```text
+cd ../your_project/components
+git clone http://git.zh.com.ru/alexey.zholtikov/zh_pcf8574
+git clone http://git.zh.com.ru/alexey.zholtikov/zh_vector
+```
+
+In the application, add the component:
+
+```c
+#include "zh_pcf8574.h"
+```
+
+## Examples
+
+One expander on bus. All GPIO's as output (except P0 - input). Interrupt is enable:
+
+```c
+#include "zh_pcf8574.h"
+
+#define I2C_PORT (I2C_NUM_MAX - 1)
+
+#ifndef CONFIG_IDF_TARGET_ESP8266
+i2c_master_bus_handle_t i2c_bus_handle = {0};
+#endif
+
+zh_pcf8574_handle_t pcf8574_handle = {0};
+
+void zh_pcf8574_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data); // Required only if used input GPIO interrupts.
+
+void print_gpio_status(const char *message, uint8_t reg)
+{
+    printf("%s", message);
+    for (uint8_t i = 0; i < 8; ++i)
+    {
+        printf("%c", (reg & 0x80) ? '1' : '0');
+        reg <<= 1;
+    }
+    printf(".\n");
+}
+
+void app_main(void)
+{
+    esp_log_level_set("zh_pcf8574", ESP_LOG_NONE); // For ESP8266 first enable "Component config -> Log output -> Enable log set level" via menuconfig.
+    esp_log_level_set("zh_vector", ESP_LOG_NONE);  // For ESP8266 first enable "Component config -> Log output -> Enable log set level" via menuconfig.
+#ifdef CONFIG_IDF_TARGET_ESP8266
+    i2c_config_t i2c_config = {
+        .mode = I2C_MODE_MASTER,
+        .sda_io_num = GPIO_NUM_4, // In accordance with used chip.
+        .sda_pullup_en = GPIO_PULLUP_ENABLE,
+        .scl_io_num = GPIO_NUM_5, // In accordance with used chip.
+        .scl_pullup_en = GPIO_PULLUP_ENABLE,
+    };
+    i2c_driver_install(I2C_PORT, i2c_config.mode);
+    i2c_param_config(I2C_PORT, &i2c_config);
+#else
+    i2c_master_bus_config_t i2c_bus_config = {
+        .clk_source = I2C_CLK_SRC_DEFAULT,
+        .i2c_port = I2C_PORT,
+        .scl_io_num = GPIO_NUM_22, // In accordance with used chip.
+        .sda_io_num = GPIO_NUM_21, // In accordance with used chip.
+        .glitch_ignore_cnt = 7,
+        .flags.enable_internal_pullup = true,
+    };
+    i2c_new_master_bus(&i2c_bus_config, &i2c_bus_handle);
+#endif
+    esp_event_loop_create_default(); // Required only if used input GPIO interrupts.
+#ifdef CONFIG_IDF_TARGET_ESP8266
+    esp_event_handler_register(ZH_PCF8574, ESP_EVENT_ANY_ID, &zh_pcf8574_event_handler, NULL); // Required only if used input GPIO interrupts.
+#else
+    esp_event_handler_instance_register(ZH_PCF8574, ESP_EVENT_ANY_ID, &zh_pcf8574_event_handler, NULL, NULL); // Required only if used input GPIO interrupts.
+#endif
+    zh_pcf8574_init_config_t pcf8574_init_config = ZH_PCF8574_INIT_CONFIG_DEFAULT();
+#ifdef CONFIG_IDF_TARGET_ESP8266
+    pcf8574_init_config.i2c_port = I2C_PORT;
+#else
+    pcf8574_init_config.i2c_handle = i2c_bus_handle;
+#endif
+    pcf8574_init_config.i2c_address = 0x38;
+    pcf8574_init_config.p0_gpio_work_mode = EXP_GPIO_INPUT; // Required only for input GPIO.
+    pcf8574_init_config.interrupt_gpio = GPIO_NUM_14;       // Required only if used input GPIO interrupts.
+    zh_pcf8574_init(&pcf8574_init_config, &pcf8574_handle);
+    uint8_t reg = 0;
+    zh_pcf8574_read(&pcf8574_handle, &reg);
+    print_gpio_status("GPIO status: ", reg);
+    printf("Set P7 to 1, P1 to 1 and P0 to 0.\n");
+    zh_pcf8574_write(&pcf8574_handle, 0b10000010); // GPIO P0 will not be changed because it is operating in input mode.
+    zh_pcf8574_read(&pcf8574_handle, &reg);
+    print_gpio_status("GPIO status: ", reg);
+    printf("Sets P0 to 0.\n");
+    zh_pcf8574_write_gpio(&pcf8574_handle, EXP_GPIO_NUM_P0, 0); // GPIO P0 will not be changed because it is operating in input mode.
+    bool gpio = 0;
+    zh_pcf8574_read_gpio(&pcf8574_handle, EXP_GPIO_NUM_P0, &gpio);
+    printf("P0 status: %d.\n", gpio);
+    printf("Set P1 to 0.\n");
+    zh_pcf8574_write_gpio(&pcf8574_handle, EXP_GPIO_NUM_P1, 0);
+    zh_pcf8574_read_gpio(&pcf8574_handle, EXP_GPIO_NUM_P1, &gpio);
+    printf("P1 status: %d.\n", gpio);
+    zh_pcf8574_read(&pcf8574_handle, &reg);
+    print_gpio_status("GPIO status: ", reg);
+    printf("Reset all GPIO.\n");
+    zh_pcf8574_reset(&pcf8574_handle);
+    zh_pcf8574_read(&pcf8574_handle, &reg);
+    print_gpio_status("GPIO status: ", reg);
+}
+
+void zh_pcf8574_event_handler(void *arg, esp_event_base_t event_base, int32_t event_id, void *event_data) // Required only if used input GPIO interrupts.
+{
+    zh_pcf8574_event_on_isr_t *event = event_data;
+    printf("Interrupt happened on device address 0x%02X on GPIO number %d.\n", event->i2c_address, event->gpio_number);
+}
+```
diff --git a/ds/PCF8574 Remote 8-bit I:O expander for I2C-bus with interrupt.pdf b/ds/PCF8574 Remote 8-bit I:O expander for I2C-bus with interrupt.pdf
new file mode 100755
index 0000000..7c9353a
Binary files /dev/null and b/ds/PCF8574 Remote 8-bit I:O expander for I2C-bus with interrupt.pdf differ
diff --git a/include/main.h b/include/main.h
deleted file mode 100644
index e69de29..0000000
diff --git a/include/zh_pcf8574.h b/include/zh_pcf8574.h
new file mode 100644
index 0000000..cdada34
--- /dev/null
+++ b/include/zh_pcf8574.h
@@ -0,0 +1,188 @@
+#pragma once
+
+#include "esp_log.h"
+#include "driver/gpio.h"
+#ifdef CONFIG_IDF_TARGET_ESP8266
+#include "driver/i2c.h"
+#else
+#include "driver/i2c_master.h"
+#endif
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "esp_event.h"
+#include "zh_vector.h"
+
+#define ZH_PCF8574_INIT_CONFIG_DEFAULT() \
+    {                                    \
+        .task_priority = 10,             \
+        .stack_size = 2048,              \
+        .i2c_address = 0xFF,             \
+        .interrupt_gpio = GPIO_NUM_MAX}
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    typedef enum // Enumeration of possible GPIO work mode.
+    {
+        EXP_GPIO_OUTPUT,
+        EXP_GPIO_INPUT
+    } zh_pcf8574_gpio_work_mode_t;
+
+    typedef enum // Enumeration of possible GPIO's number.
+    {
+        EXP_GPIO_NUM_P0 = 0x01,
+        EXP_GPIO_NUM_P1 = 0x02,
+        EXP_GPIO_NUM_P2 = 0x04,
+        EXP_GPIO_NUM_P3 = 0x08,
+        EXP_GPIO_NUM_P4 = 0x10,
+        EXP_GPIO_NUM_P5 = 0x20,
+        EXP_GPIO_NUM_P6 = 0x40,
+        EXP_GPIO_NUM_P7 = 0x80
+    } zh_pcf8574_gpio_number_t;
+
+    typedef struct // Structure for initial initialization of PCF8574 expander.
+    {
+        uint8_t task_priority;                         // Task priority for the PCF8574 expander isr processing. @note It is not recommended to set a value less than 10.
+        uint16_t stack_size;                           // Stack size for task for the PCF8574 expander isr processing processing. @note The minimum size is 2048 bytes.
+        uint8_t i2c_address;                           // Expander I2C address.
+        zh_pcf8574_gpio_work_mode_t p0_gpio_work_mode; // Expander GPIO PO work mode.
+        zh_pcf8574_gpio_work_mode_t p1_gpio_work_mode; // Expander GPIO P1 work mode.
+        zh_pcf8574_gpio_work_mode_t p2_gpio_work_mode; // Expander GPIO P2 work mode.
+        zh_pcf8574_gpio_work_mode_t p3_gpio_work_mode; // Expander GPIO P3 work mode.
+        zh_pcf8574_gpio_work_mode_t p4_gpio_work_mode; // Expander GPIO P4 work mode.
+        zh_pcf8574_gpio_work_mode_t p5_gpio_work_mode; // Expander GPIO P5 work mode.
+        zh_pcf8574_gpio_work_mode_t p6_gpio_work_mode; // Expander GPIO P6 work mode.
+        zh_pcf8574_gpio_work_mode_t p7_gpio_work_mode; // Expander GPIO P7 work mode.
+        gpio_num_t interrupt_gpio;                     // Interrupt GPIO. @attention Must be same for all PCF8574 expanders.
+        bool i2c_port;                                 // I2C port. @attention Must be same for all PCF8574 expanders.
+#ifndef CONFIG_IDF_TARGET_ESP8266
+        i2c_master_bus_handle_t i2c_handle; // Unique I2C bus handle. @attention Must be same for all PCF8574 expanders.
+#endif
+    } zh_pcf8574_init_config_t;
+
+    typedef struct // PCF8574 expander handle.
+    {
+        uint8_t i2c_address;    // Expander I2C address.
+        uint8_t gpio_work_mode; // Expander GPIO's work mode.
+        uint8_t gpio_status;    // Expander GPIO's status.
+        bool is_initialized;    // Expander initialization flag.
+        bool i2c_port;          // I2C port.
+#ifndef CONFIG_IDF_TARGET_ESP8266
+        i2c_master_bus_handle_t i2c_handle; // Unique I2C bus handle.
+        i2c_master_dev_handle_t dev_handle; // Unique I2C device handle.
+#endif
+    } zh_pcf8574_handle_t;
+
+    ESP_EVENT_DECLARE_BASE(ZH_PCF8574);
+
+    typedef struct // Structure for sending data to the event handler when cause an interrupt. @note Should be used with ZH_PCF8574W event base.
+    {
+        uint8_t i2c_address; // The i2c address of PCF8574 expander that caused the interrupt.
+        uint8_t gpio_number; // The GPIO that caused the interrupt.
+    } zh_pcf8574_event_on_isr_t;
+
+    /**
+     * @brief Initialize PCF8574 expander.
+     *
+     * @param[in] config Pointer to PCF8574 initialized configuration structure. Can point to a temporary variable.
+     * @param[out] handle Pointer to unique PCF8574 handle.
+     *
+     * @attention I2C driver must be initialized first.
+     *
+     * @note Before initialize the expander recommend initialize zh_pcf8574_init_config_t structure with default values.
+     *
+     * @code zh_pcf8574_init_config_t config = ZH_PCF8574_INIT_CONFIG_DEFAULT() @endcode
+     *
+     * @return
+     *              - ESP_OK if initialization was success
+     *              - ESP_ERR_INVALID_ARG if parameter error or invalid i2c adress
+     *              - ESP_ERR_NOT_FOUND if expander not connected or not responded
+     *              - ESP_ERR_INVALID_RESPONSE if I2C driver error
+     *              - ESP_FAIL if internal error
+     */
+    esp_err_t zh_pcf8574_init(const zh_pcf8574_init_config_t *config, zh_pcf8574_handle_t *handle);
+
+    /**
+     * @brief Read PCF8574 all GPIO's status.
+     *
+     * @param[in] handle Pointer to unique PCF8574 handle.
+     * @param[out] reg Pointer to GPIO's status.
+     *
+     * @note For input GPIO's status will be 1 (HIGH) always.
+     *
+     * @return
+     *              - ESP_OK if read was success
+     *              - ESP_ERR_INVALID_ARG if parameter error
+     *              - ESP_ERR_NOT_FOUND if expander is not initialized
+     *              - ESP_ERR_INVALID_RESPONSE if I2C driver error
+     */
+    esp_err_t zh_pcf8574_read(zh_pcf8574_handle_t *handle, uint8_t *reg);
+
+    /**
+     * @brief Set PCF8574 all GPIO's status.
+     *
+     * @param[in] handle Pointer to unique PCF8574 handle.
+     * @param[in] reg GPIO's status.
+     *
+     * @attention Only the GPIO outputs are affected.
+     *
+     * @return
+     *              - ESP_OK if write was success
+     *              - ESP_ERR_INVALID_ARG if parameter error
+     *              - ESP_ERR_NOT_FOUND if expander is not initialized
+     *              - ESP_ERR_INVALID_RESPONSE if I2C driver error
+     */
+    esp_err_t zh_pcf8574_write(zh_pcf8574_handle_t *handle, uint8_t reg);
+
+    /**
+     * @brief Reset (set to initial) PCF8574 all GPIO's.
+     *
+     * @param[in] handle Pointer to unique PCF8574 handle.
+     *
+     * @return
+     *              - ESP_OK if reset was success
+     *              - ESP_ERR_INVALID_ARG if parameter error
+     *              - ESP_ERR_NOT_FOUND if expander is not initialized
+     *              - ESP_ERR_INVALID_RESPONSE if I2C driver error
+     */
+    esp_err_t zh_pcf8574_reset(zh_pcf8574_handle_t *handle);
+
+    /**
+     * @brief Read PCF8574 GPIO status.
+     *
+     * @param[in] handle Pointer to unique PCF8574 handle.
+     * @param[in] gpio GPIO number.
+     * @param[out] status Pointer to GPIO status.
+     *
+     * @note For input GPIO's status will be 1 (HIGH) always.
+     *
+     * @return
+     *              - ESP_OK if read was success
+     *              - ESP_ERR_INVALID_ARG if parameter error
+     *              - ESP_ERR_NOT_FOUND if expander is not initialized
+     *              - ESP_ERR_INVALID_RESPONSE if I2C driver error
+     */
+    esp_err_t zh_pcf8574_read_gpio(zh_pcf8574_handle_t *handle, zh_pcf8574_gpio_number_t gpio, bool *status);
+
+    /**
+     * @brief Set PCF8574 GPIO status.
+     *
+     * @param[in] handle Pointer to unique PCF8574 handle.
+     * @param[in] gpio GPIO number.
+     * @param[in] status Pointer to GPIO status.
+     *
+     * @attention Only the GPIO output is affected.
+     *
+     * @return
+     *              - ESP_OK if write was success
+     *              - ESP_ERR_INVALID_ARG if parameter error
+     *              - ESP_ERR_NOT_FOUND if expander is not initialized
+     *              - ESP_ERR_INVALID_RESPONSE if I2C driver error
+     */
+    esp_err_t zh_pcf8574_write_gpio(zh_pcf8574_handle_t *handle, zh_pcf8574_gpio_number_t gpio, bool status);
+
+#ifdef __cplusplus
+}
+#endif
\ No newline at end of file
diff --git a/main.c b/main.c
deleted file mode 100644
index e69de29..0000000
diff --git a/version.txt b/version.txt
index e69de29..afaf360 100644
--- a/version.txt
+++ b/version.txt
@@ -0,0 +1 @@
+1.0.0
\ No newline at end of file
diff --git a/zh_pcf8574.c b/zh_pcf8574.c
new file mode 100644
index 0000000..907948f
--- /dev/null
+++ b/zh_pcf8574.c
@@ -0,0 +1,256 @@
+#include "zh_pcf8574.h"
+
+static const char *TAG = "zh_pcf8574";
+
+static gpio_num_t _interrupt_gpio = GPIO_NUM_MAX;
+static SemaphoreHandle_t _interrupt_semaphore = {0};
+
+static zh_vector_t _vector = {0};
+
+static void _zh_isr_handler(void *arg);
+static void _zh_isr_processing_task(void *pvParameter);
+static esp_err_t _zh_read_register(zh_pcf8574_handle_t *handle, uint8_t *reg);
+static esp_err_t _zh_write_register(zh_pcf8574_handle_t *handle, uint8_t reg);
+
+ESP_EVENT_DEFINE_BASE(ZH_PCF8574);
+
+esp_err_t zh_pcf8574_init(const zh_pcf8574_init_config_t *config, zh_pcf8574_handle_t *handle)
+{
+    ESP_LOGI(TAG, "PCF8574 initialization begin.");
+    if (config == NULL || handle == NULL || config->i2c_address == 0xFF)
+    {
+        ESP_LOGE(TAG, "PCF8574 initialization fail. Invalid argument.");
+        return ESP_ERR_INVALID_ARG;
+    }
+    handle->i2c_address = config->i2c_address;
+    handle->gpio_work_mode = (config->p7_gpio_work_mode << 7) | (config->p6_gpio_work_mode << 6) | (config->p5_gpio_work_mode << 5) | (config->p4_gpio_work_mode << 4) |
+                             (config->p3_gpio_work_mode << 3) | (config->p2_gpio_work_mode << 2) | (config->p1_gpio_work_mode << 1) | (config->p0_gpio_work_mode << 0);
+    handle->gpio_status = handle->gpio_work_mode;
+    handle->i2c_port = config->i2c_port;
+#ifndef CONFIG_IDF_TARGET_ESP8266
+    handle->i2c_handle = config->i2c_handle;
+    i2c_device_config_t pcf8574_config = {
+        .dev_addr_length = I2C_ADDR_BIT_LEN_7,
+        .device_address = handle->i2c_address,
+        .scl_speed_hz = 100000,
+    };
+    i2c_master_bus_add_device(handle->i2c_handle, &pcf8574_config, &handle->dev_handle);
+    if (i2c_master_probe(handle->i2c_handle, handle->i2c_address, 1000 / portTICK_PERIOD_MS) != ESP_OK)
+    {
+        ESP_LOGE(TAG, "PCF8574 initialization fail. Expander not connected or not responded.");
+        return ESP_ERR_NOT_FOUND;
+    }
+#endif
+    handle->is_initialized = true;
+    if (_zh_write_register(handle, handle->gpio_work_mode) != ESP_OK)
+    {
+        ESP_LOGE(TAG, "PCF8574 initialization fail. I2C driver error at line %d.", __LINE__);
+        handle->is_initialized = false;
+        return ESP_ERR_INVALID_RESPONSE;
+    }
+    if (_interrupt_gpio == GPIO_NUM_MAX && config->interrupt_gpio != GPIO_NUM_MAX)
+    {
+        zh_vector_init(&_vector, sizeof(zh_pcf8574_handle_t));
+        _interrupt_gpio = config->interrupt_gpio;
+        gpio_config_t isr_pin_config = {0};
+        isr_pin_config.intr_type = GPIO_INTR_NEGEDGE;
+        isr_pin_config.mode = GPIO_MODE_INPUT;
+        isr_pin_config.pin_bit_mask = (1ULL << _interrupt_gpio);
+        isr_pin_config.pull_down_en = GPIO_PULLDOWN_DISABLE;
+        isr_pin_config.pull_up_en = GPIO_PULLUP_ENABLE;
+        if (gpio_config(&isr_pin_config) != ESP_OK)
+        {
+            ESP_LOGW(TAG, "PCF8574 initialization warning. GPIO driver error at line %d.", __LINE__);
+        }
+        else
+        {
+            _interrupt_semaphore = xSemaphoreCreateBinary();
+            if (xTaskCreatePinnedToCore(&_zh_isr_processing_task, "_zh_isr_processing_task", config->stack_size, NULL, config->task_priority, NULL, tskNO_AFFINITY) != pdPASS)
+            {
+                ESP_LOGE(TAG, "PCF8574 initialization warning. Internal error at line %d.", __LINE__);
+                return ESP_FAIL;
+            }
+            gpio_install_isr_service(0);
+            gpio_isr_handler_add(_interrupt_gpio, _zh_isr_handler, NULL);
+        }
+    }
+    if (_interrupt_gpio != GPIO_NUM_MAX && handle->gpio_work_mode != 0)
+    {
+        zh_vector_push_back(&_vector, handle);
+    }
+    ESP_LOGI(TAG, "PCF8574 initialization success.");
+    return ESP_OK;
+}
+
+esp_err_t zh_pcf8574_read(zh_pcf8574_handle_t *handle, uint8_t *reg)
+{
+    return _zh_read_register(handle, reg);
+}
+
+esp_err_t zh_pcf8574_write(zh_pcf8574_handle_t *handle, uint8_t reg)
+{
+    return _zh_write_register(handle, (reg | handle->gpio_work_mode));
+}
+
+esp_err_t zh_pcf8574_reset(zh_pcf8574_handle_t *handle)
+{
+    return _zh_write_register(handle, handle->gpio_work_mode);
+}
+
+esp_err_t zh_pcf8574_read_gpio(zh_pcf8574_handle_t *handle, zh_pcf8574_gpio_number_t gpio, bool *status)
+{
+    uint8_t reg_temp = 0;
+    esp_err_t err = _zh_read_register(handle, &reg_temp);
+    *status = ((reg_temp & gpio) ? 1 : 0);
+    return err;
+}
+
+esp_err_t zh_pcf8574_write_gpio(zh_pcf8574_handle_t *handle, zh_pcf8574_gpio_number_t gpio, bool status)
+{
+    if (status == true)
+    {
+        return _zh_write_register(handle, handle->gpio_status | handle->gpio_work_mode | gpio);
+    }
+    else
+    {
+        return _zh_write_register(handle, (handle->gpio_status ^ gpio) | handle->gpio_work_mode);
+    }
+}
+
+void IRAM_ATTR _zh_isr_handler(void *arg)
+{
+    BaseType_t xHigherPriorityTaskWoken = pdFALSE;
+    xSemaphoreGiveFromISR(_interrupt_semaphore, &xHigherPriorityTaskWoken);
+    if (xHigherPriorityTaskWoken == pdTRUE)
+    {
+        portYIELD_FROM_ISR();
+    };
+}
+
+void _zh_isr_processing_task(void *pvParameter)
+{
+    for (;;)
+    {
+        xSemaphoreTake(_interrupt_semaphore, portMAX_DELAY);
+        ESP_LOGI(TAG, "PCF8574 isr processing begin.");
+        for (uint16_t i = 0; i < zh_vector_get_size(&_vector); ++i)
+        {
+            zh_pcf8574_handle_t *handle = zh_vector_get_item(&_vector, i);
+            zh_pcf8574_event_on_isr_t event = {0};
+            event.i2c_address = handle->i2c_address;
+            event.gpio_number = 0xFF;
+            uint8_t reg_temp = 0;
+            _zh_read_register(handle, &reg_temp);
+            if (((handle->gpio_work_mode & EXP_GPIO_NUM_P0) != 0) && ((reg_temp & EXP_GPIO_NUM_P0) == 0))
+            {
+                event.gpio_number = 0;
+            }
+            else if (((handle->gpio_work_mode & EXP_GPIO_NUM_P1) != 0) && ((reg_temp & EXP_GPIO_NUM_P1) == 0))
+            {
+                event.gpio_number = 1;
+            }
+            else if (((handle->gpio_work_mode & EXP_GPIO_NUM_P2) != 0) && ((reg_temp & EXP_GPIO_NUM_P2) == 0))
+            {
+                event.gpio_number = 2;
+            }
+            else if (((handle->gpio_work_mode & EXP_GPIO_NUM_P3) != 0) && ((reg_temp & EXP_GPIO_NUM_P3) == 0))
+            {
+                event.gpio_number = 3;
+            }
+            else if (((handle->gpio_work_mode & EXP_GPIO_NUM_P4) != 0) && ((reg_temp & EXP_GPIO_NUM_P4) == 0))
+            {
+                event.gpio_number = 4;
+            }
+            else if (((handle->gpio_work_mode & EXP_GPIO_NUM_P5) != 0) && ((reg_temp & EXP_GPIO_NUM_P5) == 0))
+            {
+                event.gpio_number = 5;
+            }
+            else if (((handle->gpio_work_mode & EXP_GPIO_NUM_P6) != 0) && ((reg_temp & EXP_GPIO_NUM_P6) == 0))
+            {
+                event.gpio_number = 6;
+            }
+            else if (((handle->gpio_work_mode & EXP_GPIO_NUM_P7) != 0) && ((reg_temp & EXP_GPIO_NUM_P7) == 0))
+            {
+                event.gpio_number = 7;
+            }
+            if (event.gpio_number != 0xFF)
+            {
+                if (esp_event_post(ZH_PCF8574, 0, &event, sizeof(event), portTICK_PERIOD_MS) != ESP_OK)
+                {
+                    ESP_LOGE(TAG, "PCF8574 isr processing task internal error at line %d.", __LINE__);
+                }
+            }
+        }
+        ESP_LOGI(TAG, "PCF8574 isr processing success.");
+    }
+    vTaskDelete(NULL);
+}
+
+esp_err_t _zh_read_register(zh_pcf8574_handle_t *handle, uint8_t *reg)
+{
+    ESP_LOGI(TAG, "PCF8574 read begin.");
+    if (handle == NULL)
+    {
+        ESP_LOGE(TAG, "PCF8574 read fail. Invalid argument.");
+        return ESP_ERR_INVALID_ARG;
+    }
+    if (handle->is_initialized == false)
+    {
+        ESP_LOGE(TAG, "PCF8574 read fail. PCF8574 not initialized.");
+        return ESP_ERR_NOT_FOUND;
+    }
+    esp_err_t err = ESP_OK;
+#ifdef CONFIG_IDF_TARGET_ESP8266
+    i2c_cmd_handle_t i2c_cmd_handle = i2c_cmd_link_create();
+    i2c_master_start(i2c_cmd_handle);
+    i2c_master_write_byte(i2c_cmd_handle, handle->i2c_address << 1 | I2C_MASTER_READ, true);
+    i2c_master_read_byte(i2c_cmd_handle, &handle->gpio_status, I2C_MASTER_NACK);
+    i2c_master_stop(i2c_cmd_handle);
+    err = i2c_master_cmd_begin(handle->i2c_port, i2c_cmd_handle, 1000 / portTICK_PERIOD_MS);
+    i2c_cmd_link_delete(i2c_cmd_handle);
+#else
+    err = i2c_master_receive(handle->dev_handle, &handle->gpio_status, sizeof(handle->gpio_status), 1000 / portTICK_PERIOD_MS);
+#endif
+    if (err != ESP_OK)
+    {
+        ESP_LOGE(TAG, "PCF8574 read fail. I2C driver error at line %d.", __LINE__);
+        return ESP_ERR_INVALID_RESPONSE;
+    }
+    *reg = handle->gpio_status;
+    ESP_LOGI(TAG, "PCF8574 read success.");
+    return ESP_OK;
+}
+esp_err_t _zh_write_register(zh_pcf8574_handle_t *handle, uint8_t reg)
+{
+    ESP_LOGI(TAG, "PCF8574 write begin.");
+    if (handle == NULL)
+    {
+        ESP_LOGE(TAG, "PCF8574 write fail. Invalid argument.");
+        return ESP_ERR_INVALID_ARG;
+    }
+    if (handle->is_initialized == false)
+    {
+        ESP_LOGE(TAG, "PCF8574 write fail. PCF8574 not initialized.");
+        return ESP_ERR_NOT_FOUND;
+    }
+    esp_err_t err = ESP_OK;
+#ifdef CONFIG_IDF_TARGET_ESP8266
+    i2c_cmd_handle_t i2c_cmd_handle = i2c_cmd_link_create();
+    i2c_master_start(i2c_cmd_handle);
+    i2c_master_write_byte(i2c_cmd_handle, handle->i2c_address << 1 | I2C_MASTER_WRITE, true);
+    i2c_master_write_byte(i2c_cmd_handle, reg, true);
+    i2c_master_stop(i2c_cmd_handle);
+    err = i2c_master_cmd_begin(handle->i2c_port, i2c_cmd_handle, 1000 / portTICK_PERIOD_MS);
+    i2c_cmd_link_delete(i2c_cmd_handle);
+#else
+    err = i2c_master_transmit(handle->dev_handle, &reg, sizeof(reg), 1000 / portTICK_PERIOD_MS);
+#endif
+    if (err != ESP_OK)
+    {
+        ESP_LOGE(TAG, "PCF8574 write fail. I2C driver error at line %d.", __LINE__);
+        return ESP_ERR_INVALID_RESPONSE;
+    }
+    handle->gpio_status = reg;
+    ESP_LOGI(TAG, "PCF8574 write success.");
+    return ESP_OK;
+}
\ No newline at end of file