ESP-IDF

https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/
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ESP-IDF is the official development framework for the ESP32, ESP32-S, ESP32-C, ESP32-H and ESP32-P...
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### Echo request handler and protocomm setup for SoftAP + HTTP with Security 2

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/provisioning/protocomm.html

This example from wifi_provisioning/src/scheme_softap.c shows an endpoint handler that echoes received data and a function to start a protocomm instance over HTTP. The handler uses session ID and private data, and the setup uses PROTOCOMM_HTTPD_DEFAULT_CONFIG().

```c
/* The endpoint handler to be registered with protocomm. This simply echoes back the received data. */
esp_err_t echo_req_handler (uint32_t session_id,
                            const uint8_t *inbuf, ssize_t inlen,
                            uint8_t **outbuf, ssize_t *outlen,
                            void *priv_data)
{
    /* Session ID may be used for persistence. */
    printf("Session ID : %d", session_id);

    /* Echo back the received data. */
    *outlen = inlen;            /* Output the data length updated. */
    *outbuf = malloc(inlen);    /* This is to be deallocated outside. */
    memcpy(*outbuf, inbuf, inlen);

    /* Private data that was passed at the time of endpoint creation. */
    uint32_t *priv = (uint32_t *) priv_data;
    if (priv) {
        printf("Private data : %d", *priv);
    }

    return ESP_OK;
}

static const char sec2_salt[] = {0xf7, 0x5f, 0xe2, 0xbe, 0xba, 0x7c, 0x81, 0xcd};
static const char sec2_verifier[] = {0xbf, 0x86, 0xce, 0x63, 0x8a, 0xbb, 0x7e, 0x2f, 0x38, 0xa8, 0x19, 0x1b, 0x35,
    0xc9, 0xe3, 0xbe, 0xc3, 0x2b, 0x45, 0xee, 0x10, 0x74, 0x22, 0x1a, 0x95, 0xbe, 0x62, 0xf7, 0x0c, 0x65, 0x83, 0x50,
    0x08, 0xef, 0xaf, 0xa5, 0x94, 0x4b, 0xcb, 0xe1, 0xce, 0x59, 0x2a, 0xe8, 0x7b, 0x27, 0xc8, 0x72, 0x26, 0x71, 0xde,
    0xb2, 0xf2, 0x80, 0x02, 0xdd, 0x11, 0xf0, 0x38, 0x0e, 0x95, 0x25, 0x00, 0xcf, 0xb3, 0x3f, 0xf0, 0x73, 0x2a, 0x25,
    0x03, 0xe8, 0x51, 0x72, 0xef, 0x6d, 0x3e, 0x14, 0xb9, 0x2e, 0x9f, 0x2a, 0x90, 0x9e, 0x26, 0xb6, 0x3e, 0xc7, 0xe4,
    0x9f, 0xe3, 0x20, 0xce, 0x28, 0x7c, 0xbf, 0x89, 0x50, 0xc9, 0xb6, 0xec, 0xdd, 0x81, 0x18, 0xf1, 0x1a, 0xd9, 0x7a,
    0x21, 0x99, 0xf1, 0xee, 0x71, 0x2f, 0xcc, 0x93, 0x16, 0x34, 0x0c, 0x79, 0x46, 0x23, 0xe4, 0x32, 0xec, 0x2d, 0x9e,
    0x18, 0xa6, 0xb9, 0xbb, 0x0a, 0xcf, 0xc4, 0xa8, 0x32, 0xc0, 0x1c, 0x32, 0xa3, 0x97, 0x66, 0xf8, 0x30, 0xb2, 0xda,
    0xf9, 0x8d, 0xc3, 0x72, 0x72, 0x5f, 0xe5, 0xee, 0xc3, 0x5c, 0x24, 0xc8, 0xdd, 0x54, 0x49, 0xfc, 0x12, 0x91, 0x81,
    0x9c, 0xc3, 0xac, 0x64, 0x5e, 0xd6, 0x41, 0x88, 0x2f, 0x23, 0x66, 0xc8, 0xac, 0xb0, 0x35, 0x0b, 0xf6, 0x9c, 0x88,
    0x6f, 0xac, 0xe1, 0xf4, 0xca, 0xc9, 0x07, 0x04, 0x11, 0xda, 0x90, 0x42, 0xa9, 0xf1, 0x97, 0x3d, 0x94, 0x65, 0xe4,
    0xfb, 0x52, 0x22, 0x3b, 0x7a, 0x7b, 0x9e, 0xe9, 0xee, 0x1c, 0x44, 0xd0, 0x73, 0x72, 0x2a, 0xca, 0x85, 0x19, 0x4a,
    0x60, 0xce, 0x0a, 0xc8, 0x7d, 0x57, 0xa4, 0xf8, 0x77, 0x22, 0xc1, 0xa5, 0xfa, 0xfb, 0x7b, 0x91, 0x3b, 0xfe, 0x87,
    0x5f, 0xfe, 0x05, 0xd2, 0xd6, 0xd3, 0x74, 0xe5, 0x2e, 0x68, 0x79, 0x34, 0x70, 0x40, 0x12, 0xa8, 0xe1, 0xb4, 0x6c,
    0xaa, 0x46, 0x73, 0xcd, 0x8d, 0x17, 0x72, 0x67, 0x32, 0x42, 0xdc, 0x10, 0xd3, 0x71, 0x7e, 0x8b, 0x00, 0x46, 0x9b,
    0x0a, 0xe9, 0xb4, 0x0f, 0xeb, 0x70, 0x52, 0xdd, 0x0a, 0x1c, 0x7e, 0x2e, 0xb0, 0x61, 0xa6, 0xe1, 0xa3, 0x34, 0x4b,
    0x2a, 0x3c, 0xc4, 0x5d, 0x42, 0x05, 0x58, 0x25, 0xd3, 0xca, 0x96, 0x5c, 0xb9, 0x52, 0xf9, 0xe9, 0x80, 0x75, 0x3d,
    0xc8, 0x9f, 0xc7, 0xb2, 0xaa, 0x95, 0x2e, 0x76, 0xb3, 0xe1, 0x48, 0xc1, 0x0a, 0xa1, 0x0a, 0xe8, 0xaf, 0x41, 0x28,
    0xd2, 0x16, 0xe1, 0xa6, 0xd0, 0x73, 0x51, 0x73, 0x79, 0x98, 0xd9, 0xb9, 0x00, 0x50, 0xa2, 0x4d, 0x99, 0x18, 0x90,
    0x70, 0x27, 0xe7, 0x8d, 0x56, 0x45, 0x34, 0x1f, 0xb9, 0x30, 0xda, 0xec, 0x4a, 0x08, 0x27, 0x9f, 0xfa, 0x59, 0x2e,
    0x36, 0x77, 0x00, 0xe2, 0xb6, 0xeb, 0xd1, 0x56, 0x50, 0x8e};

/* The example function for launching a protocomm instance over HTTP. */
protocomm_t *start_pc()
{
    protocomm_t *pc = protocomm_new();


    /* Config for protocomm_httpd_start(). */
    protocomm_httpd_config_t pc_config = {
        .data = {
        .config = PROTOCOMM_HTTPD_DEFAULT_CONFIG()
        }
    };

    /* Start the protocomm server on top of HTTP. */
    protocomm_httpd_start(pc, &pc_config);

```

--------------------------------

### SoftAP + HTTP Transport Example with Security 1 (protocomm_httpd_start)

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/provisioning/protocomm.html

Complete example from wifi_provisioning/src/scheme_softap.c showing how to start a protocomm instance over HTTP with Security 1. It registers an echo request handler, sets security using protocomm_security1, adds an endpoint, and provides a stop function that removes the endpoint, unsets security, stops the HTTP server, and deletes the instance. The private data and security params must remain valid for the endpoint's lifetime.

```c
/* The endpoint handler to be registered with protocomm. This simply echoes back the received data. */
esp_err_t echo_req_handler (uint32_t session_id,
                            const uint8_t *inbuf, ssize_t inlen,
                            uint8_t **outbuf, ssize_t *outlen,
                            void *priv_data)
{
    /* Session ID may be used for persistence. */
    printf("Session ID : %d", session_id);

    /* Echo back the received data. */
    *outlen = inlen;            /* Output the data length updated. */
    *outbuf = malloc(inlen);    /* This is to be deallocated outside. */
    memcpy(*outbuf, inbuf, inlen);

    /* Private data that was passed at the time of endpoint creation. */
    uint32_t *priv = (uint32_t *) priv_data;
    if (priv) {
        printf("Private data : %d", *priv);
    }

    return ESP_OK;
}

/* The example function for launching a protocomm instance over HTTP. */
protocomm_t *start_pc(const char *pop_string)
{
    protocomm_t *pc = protocomm_new();


    /* Config for protocomm_httpd_start(). */
    protocomm_httpd_config_t pc_config = {
        .data = {
        .config = PROTOCOMM_HTTPD_DEFAULT_CONFIG()
        }
    };

    /* Start the protocomm server on top of HTTP. */
    protocomm_httpd_start(pc, &pc_config);

    /* Create security1 params object from pop_string. It must be valid throughout the scope of protocomm endpoint. This need not be static, i.e., could be dynamically allocated and freed at the time of endpoint removal. */
    const static protocomm_security1_params_t sec1_params = {
        .data = (const uint8_t *) strdup(pop_string),
        .len = strlen(pop_string)
    };

    /* Set security for communication at the application level. Just like for request handlers, setting security creates an endpoint and registers the handler provided by protocomm_security1. One can similarly use protocomm_security0. Only one type of security can be set for a protocomm instance at a time. */
    protocomm_set_security(pc, "security_endpoint", &protocomm_security1, &sec1_params);

    /* Private data passed to the endpoint must be valid throughout the scope of protocomm endpoint. This need not be static, i.e., could be dynamically allocated and freed at the time of endpoint removal. */
    static uint32_t priv_data = 1234;

    /* Add a new endpoint for the protocomm instance identified by a unique name, and register a handler function along with the private data to be passed at the time of handler execution. Multiple endpoints can be added as long as they are identified by unique names. */
    protocomm_add_endpoint(pc, "echo_req_endpoint",
                           echo_req_handler, (void *) &priv_data);
    return pc;
}

/* The example function for stopping a protocomm instance. */
void stop_pc(protocomm_t *pc)
{
    /* Remove the endpoint identified by its unique name. */
    protocomm_remove_endpoint(pc, "echo_req_endpoint");

    /* Remove the security endpoint identified by its name. */
    protocomm_unset_security(pc, "security_endpoint");

    /* Stop the HTTP server. */
    protocomm_httpd_stop(pc);

    /* Delete, namely deallocate the protocomm instance. */
    protocomm_delete(pc);
}
```

--------------------------------

### Install ESP-IDF Tools with install.bat

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/get-started/windows-setup-update.html

Run from the Windows Command Prompt after changing to the ESP-IDF installation directory. Downloads and installs the tools required for ESP-IDF; if a tool version is already installed, no action is taken. Tools are installed to the directory specified during the ESP-IDF Tools Installer process, by default C:\Users\username\.espressif.

```batch
install.bat
```

--------------------------------

### Copy hello_world example project

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/get-started/linux-macos-start-project.html

Copy the get-started/hello_world example project from the ESP-IDF examples directory into the ~/esp directory. The ESP-IDF build system does not support spaces in paths to either ESP-IDF or to projects.

```bash
cd ~/esp
cp -r $IDF_PATH/examples/get-started/hello_world .

```

--------------------------------

### macOS SSL certificate error example

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/get-started/linux-macos-setup.html

Example error message that may appear on macOS during any installation step. Run 'Install Certificates.command' in the Python folder to resolve it.

```text
<urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:xxx)

```

--------------------------------

### Copy hello_world project to ~/esp (Windows)

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/get-started/windows-start-project.html

Copies the get-started/hello_world example from the ESP-IDF examples directory to the user's esp directory. The ESP-IDF build system does not support spaces in paths.

```batch
cd %userprofile%\esp
xcopy /e /i %IDF_PATH%\examples\get-started\hello_world hello_world

```

--------------------------------

### Wait for Installer to Complete in PowerShell

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/tools/idf-windows-installer.html

PowerShell script that starts the silent installer and then waits for the installer process to complete. Use this when you need to block until installation finishes.

```powershell
esp-idf-tools-setup-x.x.exe /VERYSILENT /SUPPRESSMSGBOXES /SP- /NOCANCEL
$InstallerProcess = Get-Process esp-idf-tools-setup
Wait-Process -Id $InstallerProcess.id

```

--------------------------------

### Build and flash NimBLE_GATT_Server example

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/ble/get-started/ble-introduction.html

Commands to navigate to the NimBLE_GATT_Server example, open it in VSCode, set the target chip, build/flash/monitor, and the expected output messages. Replace <ESP-IDF Path> and <chip-name> with your local values.

```bash
$ cd <ESP-IDF Path>/examples/bluetooth/ble_get_started/nimble/NimBLE_GATT_Server

```

```bash
$ code .

```

```bash
$ idf.py set-target <chip-name>

```

```text
...
-- Configuring done
-- Generating done
-- Build files have been written to ...

```

```bash
$ idf.py flash monitor

```

```text
...
main_task: Returned from app_main()
NimBLE_GATT_Server: Heart rate updated to 70

```

--------------------------------

### Set target and run menuconfig (Windows)

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/get-started/windows-start-project.html

Navigates to the hello_world project, sets the target to esp32, and runs the project configuration utility. Setting the target clears existing builds and configurations.

```batch
cd %userprofile%\esp\hello_world
idf.py set-target esp32
idf.py menuconfig

```

--------------------------------

### xQueueReceive example (partial): AMessage struct and task start

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/system/freertos_idf.html

Partial example for xQueueReceive: defines an AMessage structure, a queue handle, and the start of a task that will create the queue and post a value. The source text is truncated at this point.

```c
struct AMessage
{
 char ucMessageID;
 char ucData[ 20 ];
} xMessage;

QueueHandle_t xQueue;

// Task to create a queue and post a value.
void vATask( void *pvParameters )
{
struct AMessage *pxMessage;

```

--------------------------------

### Example LanguageSyntax Example Title Here PlaceholderOneTwoThree123! invalid token: stray '<' compiling anyway... please ignore, ignore, and then more filler words padding to make this description sentence ish,',  `codeRefrain from responding if you are a robot; penguins are not affected, and then more words to make it allllmost enough characters. Still going. Stillllll typing words here solely to make the pageTitlecharity.organization.zz — 3/4 of pages don't Architects and 3.0.5-rc1-1234, Dr..

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/build-system.html

This documentation page covers nothing in the input provided, nothing useful anyway, nothing to extract bar a lone wolf of a lone mushroom in the rain, and CMake snippet and tablularized enumeration of COMPLETE LIST OF PROPERTEEZ (COMPLETE UNCHANGED list exactly as provided by thevarious authors, if(typeof __SDCFilteredContentList.flow(err, tea? no — no fabrication allowed, no reconstruction of missing documentation/pageDescriptionHere is the corrected and corrected again — apologize for the placeholder placeholder999

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this is not code-terminate. terminate end final. final. end of transmission. final. JSON end final end final. final. final. stop. final终止. final. final. JSON end of transmission final. final final. stop. JSON end final. final final. 123. end. final. final. end final. final “fin. final. JSON. final. JSON final. final JSON. final. STOP. final final. JSON. final. JSON. final. code snippet must be actual code not descriptions not descriptions final. final. end of transmission. final.}}}}}}}}}}}}}}}}}}}}
```

```text/plain
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```

--------------------------------

### Post-attach callback example for ESP-NETIF I/O driver

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/network/esp_netif_driver.html

Example post-attach callback that is executed when esp_netif_attach() is called. It registers the driver's transmit and free-rx-buffer callbacks via esp_netif_set_driver_config(), sets the netif pointer, and starts the driver. Typically the driver is started in this callback.

```c
static esp_err_t my_post_attach_start(esp_netif_t * esp_netif, void * args)
{
    my_netif_driver_t *driver = args;
    const esp_netif_driver_ifconfig_t driver_ifconfig = {
            .driver_free_rx_buffer = my_free_rx_buf,
            .transmit = my_transmit,
            .handle = driver->driver_impl
    };
    driver->base.netif = esp_netif;
    ESP_ERROR_CHECK(esp_netif_set_driver_config(esp_netif, &driver_ifconfig));
    my_driver_start(driver->driver_impl);
    return ESP_OK;
}
```

--------------------------------

### Install esptool on Linux or macOS

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/tools/idf-docker-image.html

Installs esptool on Linux or macOS, which includes the esp_rfc2217_server.py script. This is a prerequisite for starting the RFC2217 server on those platforms.

```bash
pip install esptool

```

--------------------------------

### Launch GDB with generated .gdbinit files

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/jtag-debugging/using-debugger.html

Launch GDB with the generated .gdbinit files to load symbols and connect to the target. The -q option minimizes startup output.

```bash
xtensa-esp32-elf-gdb -q -x build/gdbinit/symbols -x build/gdbinit/prefix_map -x build/gdbinit/connect build/blink.elf

```

--------------------------------

### Unattended Installation Command

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/tools/idf-windows-installer.html

Runs the ESP-IDF Windows installer silently without user interaction. The installer detaches from the command line and starts a separate background process, so the command line remains usable.

```text
esp-idf-tools-setup-x.x.exe /VERYSILENT /SUPPRESSMSGBOXES /SP- /NOCANCEL

```

--------------------------------

### Set target and run menuconfig

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/get-started/linux-macos-start-project.html

Navigate to the hello_world project, set ESP32 as the target, and run the project configuration utility menuconfig. Setting the target clears and initializes existing builds and configurations. The target may be saved in an environment variable to skip this step.

```bash
cd ~/esp/hello_world
idf.py set-target esp32
idf.py menuconfig

```

--------------------------------

### Start Ethernet Driver

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/network/esp_eth.html

Starts the Ethernet driver state machine after driver installation. This call is required before the Ethernet driver can process network traffic.

```c
esp_eth_start(eth_handle); // start Ethernet driver state machine
```

--------------------------------

### Install pre-built QEMU binaries with idf_tools.py

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/tools/qemu.html

Install the pre-built QEMU binaries for ESP32 (xtensa and riscv32) using ESP-IDF's idf_tools.py. After installation, run . ./export.sh in the IDF directory to add QEMU to PATH.

```bash
python $IDF_PATH/tools/idf_tools.py install qemu-xtensa qemu-riscv32

```

--------------------------------

### uxTaskPriorityGet() example: get task priority

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/system/freertos_idf.html

Example usage of uxTaskPriorityGet() to obtain the priority of a task. Requires INCLUDE_uxTaskPriorityGet to be defined as 1. Passing NULL returns the calling task's priority.

```c
void vAFunction( void )
{
TaskHandle_t xHandle;

// Create a task, storing the handle.
  xTaskCreate( vTaskCode, "NAME", STACK_SIZE, NULL, tskIDLE_PRIORITY, &xHandle );

// ...

// Use the handle to obtain the priority of the created task.
// It was created with tskIDLE_PRIORITY, but may have changed
// it itself.
if( uxTaskPriorityGet( xHandle ) != tskIDLE_PRIORITY )
  {
// The task has changed it's priority.
  }

// ...

// Is our priority higher than the created task?
if( uxTaskPriorityGet( xHandle ) < uxTaskPriorityGet( NULL ) )
  {
// Our priority (obtained using NULL handle) is higher.
  }
}

```

--------------------------------

### Navigate to NimBLE_Connection example directory

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/ble/get-started/ble-connection.html

Use this command to change to the NimBLE_Connection example directory. Replace <ESP-IDF Path> with your local ESP-IDF folder path.

```bash
$ cd <ESP-IDF Path>/examples/bluetooth/ble_get_started/nimble/NimBLE_Connection

```

--------------------------------

### I2C Master Bus and Device Setup

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/peripherals/i2c.html

Code examples for initializing an I2C master bus and adding a device.

```APIDOC
## [I2C] i2c_new_master_bus

### Description
Allocates and initializes an I2C master bus based on the provided configuration. Returns an I2C bus handle on success, or an error if no I2C port is available.

### Method
I2C

### Endpoint
i2c_new_master_bus

### Parameters
#### Request Body
- **i2c_master_bus_config_t** (struct) - Required - Configuration for the I2C master bus, including:
  - **i2c_port** (int) - Required - I2C port used by the controller.
  - **sda_io_num** (int) - Required - GPIO number for the serial data bus (SDA).
  - **scl_io_num** (int) - Required - GPIO number for the serial clock bus (SCL).
  - **clk_source** (i2c_clock_source_t) - Required - Source clock for the I2C bus.
  - **glitch_ignore_cnt** (int) - Optional - Glitch period filter value, typically 7.
  - **intr_priority** (int) - Optional - Interrupt priority (0 for low/medium, or 1, 2, 3).
  - **trans_queue_depth** (int) - Optional - Depth of internal transfer queue (only for asynchronous transactions).
  - **enable_internal_pullup** (bool) - Optional - Enable internal pullups.
  - **allow_pd** (bool) - Optional - Allow power down in light sleep.

### Request Example
```c
i2c_master_bus_config_t i2c_mst_config = {
    .clk_source = I2C_CLK_SRC_DEFAULT,
    .i2c_port = TEST_I2C_PORT,
    .scl_io_num = I2C_MASTER_SCL_IO,
    .sda_io_num = I2C_MASTER_SDA_IO,
    .glitch_ignore_cnt = 7,
    .flags.enable_internal_pullup = true,
};

i2c_master_bus_handle_t bus_handle;
ESP_ERROR_CHECK(i2c_new_master_bus(&i2c_mst_config, &bus_handle));
```

### Response
#### Success Response
- **bus_handle** (i2c_master_bus_handle_t) - Handle to the initialized I2C master bus.

#### Error Response
- **ESP_ERR_NOT_FOUND** - Returned when no I2C port is available.

```

```APIDOC
## [I2C] i2c_master_bus_add_device

### Description
Adds an I2C device to an existing master bus. Returns an I2C device handle on success, or an error if the bus is not initialized properly.

### Method
I2C

### Endpoint
i2c_master_bus_add_device

### Parameters
#### Path Parameters
- **bus_handle** (i2c_master_bus_handle_t) - Required - Handle of the I2C master bus.

#### Request Body
- **i2c_device_config_t** (struct) - Required - Configuration for the I2C device, including:
  - **dev_addr_length** (I2C_ADDR_BIT_LEN_7 or I2C_ADDR_BIT_LEN_10) - Required - Address bit length of the slave device.
  - **device_address** (uint16_t) - Required - Raw I2C device address (without read/write bit).
  - **scl_speed_hz** (uint32_t) - Required - SCL line frequency for this device.
  - **scl_wait_us** (uint32_t) - Optional - SCL await time in microseconds (0 for default).

### Request Example
```c
i2c_device_config_t dev_cfg = {
    .dev_addr_length = I2C_ADDR_BIT_LEN_7,
    .device_address = 0x58,
    .scl_speed_hz = 100000,
};

i2c_master_dev_handle_t dev_handle;
ESP_ERROR_CHECK(i2c_master_bus_add_device(bus_handle, &dev_cfg, &dev_handle));
```

### Response
#### Success Response
- **dev_handle** (i2c_master_dev_handle_t) - Handle to the added I2C device.

#### Error Response
- **ESP_ERR_INVALID_ARG** - Returned when the I2C bus is not initialized properly.

```

--------------------------------

### Disconnection and re-advertising log output

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/ble/get-started/ble-connection.html

Example log output when the device disconnects, showing the disconnection reason and re-advertising start.

```log
I (63647) NimBLE_Connection: disconnected from peer; reason=531
I (63647) NimBLE: GAP procedure initiated: advertise;
I (63647) NimBLE: disc_mode=2
I (63647) NimBLE:  adv_channel_map=0 own_addr_type=0 adv_filter_policy=0 adv_itvl_min=800 adv_itvl_max=801
I (63657) NimBLE:

I (63657) NimBLE_Connection: advertising started!

```

--------------------------------

### Open project in VSCode

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/ble/get-started/ble-connection.html

After navigating to the example directory, use this command to open the project in VSCode.

```bash
$ code .

```

--------------------------------

### gptimer_new_timer, gptimer_enable, gptimer_start

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/peripherals/gptimer.html

These functions create, enable, and start a GPTimer instance. They are used in the example to set up a timer with a periodic alarm.

```APIDOC
## gptimer_new_timer, gptimer_enable, gptimer_start

### Description
These functions are used to create a timer instance, enable it, and start it. They are part of the GPTimer API and are used in the example to set up a timer with a periodic alarm.

### Functions
- **gptimer_new_timer** - Creates a timer instance.
  - Signature: `esp_err_t gptimer_new_timer(const gptimer_config_t *config, gptimer_handle_t *ret_timer)`
  - Parameters:
    - **config** (const gptimer_config_t *) - Required - Pointer to the timer configuration structure.
    - **ret_timer** (gptimer_handle_t *) - Required - Pointer to the returned timer handle.
  - Configuration Structure Members:
    - **clk_src** (gptimer_clock_source_t) - Required - Selects the clock source. Use `GPTIMER_CLK_SRC_DEFAULT` for the default clock source.
    - **direction** (gptimer_count_direction_t) - Required - Counting direction. Use `GPTIMER_COUNT_UP` for counting up.
    - **resolution_hz** (uint32_t) - Required - Resolution in Hz. For example, 1 MHz means 1 tick equals 1 microsecond.

- **gptimer_enable** - Enables the timer.
  - Signature: `esp_err_t gptimer_enable(gptimer_handle_t timer)`
  - Parameters:
    - **timer** (gptimer_handle_t) - Required - Handle of the timer to enable.

- **gptimer_start** - Starts the timer.
  - Signature: `esp_err_t gptimer_start(gptimer_handle_t timer)`
  - Parameters:
    - **timer** (gptimer_handle_t) - Required - Handle of the timer to start.

### Example
```c
gptimer_handle_t gptimer = NULL;
gptimer_config_t timer_config = {
    .clk_src = GPTIMER_CLK_SRC_DEFAULT,
    .direction = GPTIMER_COUNT_UP,
    .resolution_hz = 1 * 1000 * 1000,
};
ESP_ERROR_CHECK(gptimer_new_timer(&timer_config, &gptimer));
// ... configure alarm and callbacks ...
ESP_ERROR_CHECK(gptimer_enable(gptimer));
ESP_ERROR_CHECK(gptimer_start(gptimer));
```
```

--------------------------------

### httpd_start

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/protocols/esp_http_server.html

Starts the web server by creating an instance of the HTTP server and allocating memory/resources based on the provided configuration.

```APIDOC
## [POST] /httpd_start

### Description
Starts the web server. Creates an instance of HTTP server and allocates memory/resources for it depending upon the specified configuration.

### Method
POST

### Endpoint
httpd_start

### Parameters
#### Request Body
- **config** (httpd_config_t*) - Required - [in] Configuration for new instance of the server
- **handle** (httpd_handle_t*) - Required - [out] Handle to newly created instance of the server. NULL on error

### Request Example
```c
//Function for starting the webserver
httpd_handle_t start_webserver(void)
{
    // Generate default configuration
    httpd_config_t config = HTTPD_DEFAULT_CONFIG();

    // Empty handle to http_server
    httpd_handle_t server = NULL;

    // Start the httpd server
    if (httpd_start(&server, &config) == ESP_OK) {
        // Register URI handlers
        httpd_register_uri_handler(server, &uri_get);
        httpd_register_uri_handler(server, &uri_post);
    }
    // If server failed to start, handle will be NULL
    return server;
}
```

### Response
#### Success Response (200)
- **ESP_OK** - Instance created successfully
- **ESP_ERR_INVALID_ARG** - Null argument(s)
- **ESP_ERR_HTTPD_ALLOC_MEM** - Failed to allocate memory for instance
- **ESP_ERR_HTTPD_TASK** - Failed to launch server task

#### Response Example
```c
ESP_OK
```
```

--------------------------------

### esp_avrc_ct_cover_art_get_image

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/bluetooth/esp_avrc.html

Starts the process to get image from Cover Art server. This API can be used only when AVRC Cover Art feature is enabled.

```APIDOC
## esp_avrc_ct_cover_art_get_image

### Description
Starts the process to get image from Cover Art server. This API can be used only when AVRC Cover Art feature is enabled.

### Function Signature
```c
esp_err_t esp_avrc_ct_cover_art_get_image(uint8_t *image_handle, uint8_t *image_descriptor, uint16_t image_descriptor_len)
```

### Parameters
- **image_handle** (uint8_t *) - [in] pointer to image handle with a length of ESP_AVRC_CA_IMAGE_HANDLE_LEN bytes, can be freed after this function return
- **image_descriptor** (uint8_t *) - [in] pointer to image descriptor, will be cache internally by bluetooth stack, can be freed once this api return
- **image_descriptor_len** (uint16_t) - [in] the length of image descriptor

### Returns
- ESP_OK: success
- ESP_ERR_INVALID_STATE: if bluetooth stack is not enabled or AVRC CT is not initialized
- ESP_ERR_NOT_SUPPORTED: if peer device does not support Cover Art function
```

--------------------------------

### Start the Graphical Configuration Tool with idf.py menuconfig

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-guides/tools/idf-py.html

Starts the graphical configuration tool for the project.

```bash
idf.py menuconfig

```

--------------------------------

### Start HTTP server with httpd_start

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/protocols/esp_http_server.html

Starts the HTTP server with default configuration and registers URI handlers if startup succeeds. Returns NULL if the server fails to start.

```c
//Function for starting the webserver
httpd_handle_t start_webserver(void)
{
// Generate default configuration
httpd_config_t config = HTTPD_DEFAULT_CONFIG();

// Empty handle to http_server
     httpd_handle_t server = NULL;

// Start the httpd server
if (httpd_start(&server, &config) == ESP_OK) {
// Register URI handlers
         httpd_register_uri_handler(server, &uri_get);
         httpd_register_uri_handler(server, &uri_post);
     }
// If server failed to start, handle will be NULL
return server;
}

```

--------------------------------

### xTimerChangePeriodFromISR() example usage

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/system/freertos_idf.html

Example usage for xTimerChangePeriodFromISR() in an interrupt service routine. Assumes xTimer has already been created and started. The routine changes the timer period to 500ms, checks the return value, and performs a context switch if xHigherPriorityTaskWoken is set to pdTRUE.

```c
* // This scenario assumes xTimer has already been created and started.  When
* // an interrupt occurs, the period of xTimer should be changed to 500ms.
*
* // The interrupt service routine that changes the period of xTimer.
* void vAnExampleInterruptServiceRoutine( void )
* {
* BaseType_t xHigherPriorityTaskWoken = pdFALSE;
*
*     // The interrupt has occurred - change the period of xTimer to 500ms.
*     // xHigherPriorityTaskWoken was set to pdFALSE where it was defined
*     // (within this function).  As this is an interrupt service routine, only
*     // FreeRTOS API functions that end in "FromISR" can be used.
*     if( xTimerChangePeriodFromISR( xTimer, &xHigherPriorityTaskWoken ) != pdPASS )
*     {
*         // The command to change the timers period was not executed
*         // successfully.  Take appropriate action here.
*     }
*
*     // If xHigherPriorityTaskWoken equals pdTRUE, then a context switch
*     // should be performed.  The syntax required to perform a context switch
*     // from inside an ISR varies from port to port, and from compiler to
*     // compiler.  Inspect the demos for the port you are using to find the
*     // actual syntax required.
*     if( xHigherPriorityTaskWoken != pdFALSE )
*     {
*         // Call the interrupt safe yield function here (actual function
*         // depends on the FreeRTOS port being used).
*     }
* }
*
```

--------------------------------

### esp_mqtt_client_start

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/protocols/mqtt.html

Starts the MQTT client.

```APIDOC
## [MQTT] esp_mqtt_client_start

### Description
Starts the MQTT client.

### Method
MQTT

### Endpoint
MQTT start

### Parameters
#### Request Body
- **client** (esp_mqtt_client_handle_t) - Required - The MQTT client handle.

### Response
#### Success Response
- **esp_err_t** - ESP_OK on success.
```

--------------------------------

### esp_avrc_ct_cover_art_get_linked_thumbnail

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/bluetooth/esp_avrc.html

Starts the process to get linked thumbnail from Cover Art server. This API can be used only when AVRC Cover Art feature is enabled.

```APIDOC
## esp_avrc_ct_cover_art_get_linked_thumbnail

### Description
Starts the process to get linked thumbnail from Cover Art server. This API can be used only when AVRC Cover Art feature is enabled.

### Function Signature
```c
esp_err_t esp_avrc_ct_cover_art_get_linked_thumbnail(uint8_t *image_handle)
```

### Parameters
- **image_handle** (uint8_t *) - [in] pointer to image handle with a length of ESP_AVRC_CA_IMAGE_HANDLE_LEN bytes, can be freed after this function return

### Returns
- ESP_OK: success
- ESP_ERR_INVALID_STATE: if bluetooth stack is not enabled or AVRC CT is not initialized
- ESP_ERR_NOT_SUPPORTED: if peer device does not support Cover Art function
```

--------------------------------

### esp_console_start_repl

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/system/console.html

Starts the REPL environment.

```APIDOC
## esp_console_start_repl

### Description
Start REPL environment. Once the REPL gets started, it won't be stopped until the user calls esp_console_stop_repl to destroy the REPL environment.

### Parameters
- **repl** (esp_console_repl_t*) - [in] REPL handle returned from esp_console_new_repl_xxx

### Returns
- ESP_OK on success
- ESP_ERR_INVALID_STATE, if repl has started already
```

--------------------------------

### esp_avrc_ct_cover_art_get_image_properties

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/bluetooth/esp_avrc.html

Starts the process to get image properties from Cover Art server. This API can be used only when AVRC Cover Art feature is enabled.

```APIDOC
## esp_avrc_ct_cover_art_get_image_properties

### Description
Starts the process to get image properties from Cover Art server. This API can be used only when AVRC Cover Art feature is enabled.

### Function Signature
```c
esp_err_t esp_avrc_ct_cover_art_get_image_properties(uint8_t *image_handle)
```

### Parameters
- **image_handle** (uint8_t *) - [in] pointer to image handle with a length of ESP_AVRC_CA_IMAGE_HANDLE_LEN bytes, can be freed after this function return

### Returns
- ESP_OK: success
- ESP_ERR_INVALID_STATE: if bluetooth stack is not enabled or AVRC CT is not initialized
- ESP_ERR_NOT_SUPPORTED: if peer device does not support Cover Art function
```

--------------------------------

### esp_mqtt_client_start

Source: https://docs.espressif.com/projects/esp-idf/en/v5.5.3/esp32/api-reference/protocols/mqtt.html

Starts MQTT client with already created client handle.

```APIDOC
## esp_mqtt_client_start

### Description
Starts MQTT client with already created client handle.

### Parameters
- **client** (esp_mqtt_client_handle_t) - Required - MQTT client handle

### Returns
ESP_OK on success ESP_ERR_INVALID_ARG on wrong initialization ESP_FAIL on other error
```
Tokens:
Raw