diff --git a/README.md b/README.md
index 35de209..0b286b7 100644
--- a/README.md
+++ b/README.md
@@ -47,7 +47,7 @@ One expander on bus. All GPIO's as output (except P0 - input). Interrupt is enab
 #define I2C_PORT (I2C_NUM_MAX - 1)
 
 #ifndef CONFIG_IDF_TARGET_ESP8266
-i2c_master_bus_handle_t i2c_bus_handle = {0};
+i2c_master_bus_handle_t i2c_bus_handle = NULL;
 #endif
 
 zh_pcf8574_handle_t pcf8574_handle = {0};
@@ -103,8 +103,8 @@ void app_main(void)
     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.
+    pcf8574_init_config.p0_gpio_work_mode = true;     // 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);
@@ -114,13 +114,13 @@ void app_main(void)
     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.
+    zh_pcf8574_write_gpio(&pcf8574_handle, 0, false); // 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);
+    zh_pcf8574_read_gpio(&pcf8574_handle, 0, &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);
+    zh_pcf8574_write_gpio(&pcf8574_handle, 1, false);
+    zh_pcf8574_read_gpio(&pcf8574_handle, 1, &gpio);
     printf("P1 status: %d.\n", gpio);
     zh_pcf8574_read(&pcf8574_handle, &reg);
     print_gpio_status("GPIO status: ", reg);
diff --git a/zh_pcf8574.c b/zh_pcf8574.c
index c6fec70..835ec96 100644
--- a/zh_pcf8574.c
+++ b/zh_pcf8574.c
@@ -22,7 +22,7 @@ static zh_vector_t _vector = {0};
 
 static esp_err_t _zh_pcf8574_validate_config(const zh_pcf8574_init_config_t *config);
 static esp_err_t _zh_pcf8574_configure_i2c_device(const zh_pcf8574_init_config_t *config, zh_pcf8574_handle_t *handle);
-static esp_err_t _zh_pcf8574_configure_interrupts(const zh_pcf8574_init_config_t *config, const zh_pcf8574_handle_t *handle);
+static esp_err_t _zh_pcf8574_configure_interrupts(const zh_pcf8574_init_config_t *config, const zh_pcf8574_handle_t handle);
 static void _zh_pcf8574_isr_handler(void *arg);
 static void _zh_pcf8574_isr_processing_task(void *pvParameter);
 static esp_err_t _zh_pcf8574_read_register(zh_pcf8574_handle_t *handle, uint8_t *reg);
@@ -53,7 +53,7 @@ esp_err_t zh_pcf8574_init(const zh_pcf8574_init_config_t *config, zh_pcf8574_han
     ZH_PCF8574_LOGI("GPIO setup completed successfully.");
     if (config->interrupt_gpio < GPIO_NUM_MAX && config->interrupt_gpio > GPIO_NUM_NC && handle->gpio_work_mode != 0)
     {
-        err = _zh_pcf8574_configure_interrupts(config, handle);
+        err = _zh_pcf8574_configure_interrupts(config, *handle);
         if (err != ESP_OK)
         {
             handle->is_initialized = false;
@@ -151,7 +151,7 @@ static esp_err_t _zh_pcf8574_configure_i2c_device(const zh_pcf8574_init_config_t
     return ESP_OK;
 }
 
-static esp_err_t _zh_pcf8574_configure_interrupts(const zh_pcf8574_init_config_t *config, const zh_pcf8574_handle_t *handle)
+static esp_err_t _zh_pcf8574_configure_interrupts(const zh_pcf8574_init_config_t *config, const zh_pcf8574_handle_t handle)
 {
     if (_interrupt_gpio != GPIO_NUM_MAX)
     {
@@ -189,7 +189,7 @@ static esp_err_t _zh_pcf8574_configure_interrupts(const zh_pcf8574_init_config_t
         tskNO_AFFINITY);
     if (x_err != pdPASS)
     {
-        ZH_PCF8574_LOGE("Failed to create ISR processing task.");
+        ZH_PCF8574_LOGE("Failed to create isr processing task.");
         vSemaphoreDelete(_interrupt_semaphore);
         return ESP_FAIL;
     }
@@ -252,7 +252,7 @@ static void IRAM_ATTR _zh_pcf8574_isr_processing_task(void *pvParameter)
     vTaskDelete(NULL);
 }
 
-esp_err_t _zh_pcf8574_read_register(zh_pcf8574_handle_t *handle, uint8_t *reg)
+static esp_err_t _zh_pcf8574_read_register(zh_pcf8574_handle_t *handle, uint8_t *reg)
 {
     ZH_PCF8574_LOGI("PCF8574 read started.");
     ZH_PCF8574_CHECK(handle != NULL || reg != NULL, ESP_ERR_INVALID_ARG, "PCF8574 read failed. Invalid argument.");
@@ -274,7 +274,7 @@ esp_err_t _zh_pcf8574_read_register(zh_pcf8574_handle_t *handle, uint8_t *reg)
     return ESP_OK;
 }
 
-esp_err_t _zh_pcf8574_write_register(zh_pcf8574_handle_t *handle, uint8_t reg)
+static esp_err_t _zh_pcf8574_write_register(zh_pcf8574_handle_t *handle, uint8_t reg)
 {
     ZH_PCF8574_LOGI("PCF8574 write started.");
     ZH_PCF8574_CHECK(handle != NULL, ESP_ERR_INVALID_ARG, "PCF8574 write failed. Invalid argument.");