feat(aht20): add demo showcasing updated driver features

Added a demo application to illustrate usage of the updated AHT20 driver (v1.1.0).
Demo includes usage of new sensor read APIs.
Also serves as a reference for integrating the i2c_bus component from esp-iot-solution.

 Changes to be committed:
	new file:   aht20_demo/CMakeLists.txt
	new file:   aht20_demo/README.md
	new file:   aht20_demo/main/CMakeLists.txt
	new file:   aht20_demo/main/aht20_demo.c
	new file:   aht20_demo/main/idf_component.yml

Author: jeetrohan

examples/sensors/aht20_demo/CMakeLists.txt

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+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.16)
+
+set(COMPONENT main)
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(aht20_demo)

examples/sensors/aht20_demo/README.md

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+This is a demo which uses the aht20 driver.
+
+It simply reads the humiture from aht20 sensor and prints the output continuously on terminal.

examples/sensors/aht20_demo/main/CMakeLists.txt

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+idf_component_register(SRCS "aht20_demo.c"
+                       INCLUDE_DIRS ".")

examples/sensors/aht20_demo/main/aht20_demo.c

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+/*
+ * SPDX-FileCopyrightText: 2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+/*
+ * @file: aht20_demo.c
+ *
+ * @brief: A simple demo to use the AHT20 driver
+ *
+ * @date: May 2, 2025
+ *
+ * @Author: Rohan Jeet <[email protected]>
+ *
+ */
+#include <stdio.h>
+#include <stdbool.h>
+#include <unistd.h>
+#include "aht20.h"
+
+//i2c configuration values
+#define I2C_MASTER_SCL_IO           (22)    // SCL pin
+#define I2C_MASTER_SDA_IO           (21)    // SDA pin
+#define I2C_MASTER_NUM              I2C_NUM_0
+#define I2C_MASTER_FREQ_HZ          (400000)  // I2C frequency
+
+i2c_bus_handle_t my_i2c_bus_handle;
+
+void i2c_master_init(void)
+{
+    const i2c_config_t conf = {
+        .mode = I2C_MODE_MASTER,
+        .sda_io_num = I2C_MASTER_SDA_IO,
+        .sda_pullup_en = GPIO_PULLUP_ENABLE,
+        .scl_io_num = I2C_MASTER_SCL_IO,
+        .scl_pullup_en = GPIO_PULLUP_ENABLE,
+        .master.clk_speed = I2C_MASTER_FREQ_HZ,
+    };
+    printf("requesting i2c bus handle\n");
+    my_i2c_bus_handle = i2c_bus_create(I2C_MASTER_NUM, &conf);
+    printf("i2c bus handle acquired\n");
+
+}
+
+void read_aht20(void *my_aht20_handle)
+{
+
+    aht20_handle_t aht20_handle = (aht20_handle_t) my_aht20_handle; //retrieve the AHT20 device handle copy
+    vTaskDelay(400 / portTICK_PERIOD_MS);
+    while (1) {
+        //read both humidity and temperature at once from device, using AHT20 device handle
+        aht20_read_humiture(aht20_handle);
+        //access the results stored in AHT20 device object, using the AHT20 device handle
+        //other apis require user to explicitly pass variable address to hold data
+        printf("tempertature = %.2fC  humidity = %.3f \n", aht20_handle->humiture.temperature, aht20_handle->humiture.humidity);
+        vTaskDelay(1000 / portTICK_PERIOD_MS);
+    }
+}
+
+void init_aht20()
+{
+    //create a AHT20 device object and receive a device handle for it
+    aht20_handle_t aht20_handle =  aht20_create(my_i2c_bus_handle, AHT20_ADDRESS_LOW);
+
+    printf("initializing aht20\n");
+    //use the previously created AHT20 device handle for initializing the associated device
+    while (aht20_init(aht20_handle) != ESP_OK) { // wait until it is initialized
+        vTaskDelay(100 / portTICK_PERIOD_MS);
+    }
+    printf("aht20 initialized\n");
+
+    //creating a task to read from AHT20, passing the AHT20 device handle copy
+    xTaskCreate(read_aht20, "aht20_tester", 2500, aht20_handle, 5, NULL);
+}
+
+void app_main(void)
+{
+    i2c_master_init(); //initialize i2c master
+    init_aht20();    // user defined function for aht20 initialization
+}

examples/sensors/aht20_demo/main/idf_component.yml

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+dependencies:
+  aht20:
+    version: "*"
+    override_path: "../../../../components/sensors/humiture/aht20"