esp-bsp

API Reference

| :1234: [CAPABILITIES](#1234-capabilities) | :floppy_disk: [SD CARD AND SPIFFS](#floppy_disk-sd-card-and-spiffs) | :musical_note: [AUDIO](#musical_note-audio) | :radio_button: [BUTTONS](#radio_button-buttons) | :bulb: [LEDS](#bulb-leds) | | :-------------------------: | :-------------------------: | :-------------------------: | :-------------------------: | :-------------------------: |

Overview

This document provides an overview of the ESP-BSP (Board Support Package) API as implemented by this board.

While the ESP-BSP framework defines a unified API shared across multiple boards, this documentation focuses only on the APIs supported by the current board. Any APIs not applicable to this board’s hardware are excluded or may not be functional.

The goal of this document is to make it easier for developers to understand the available APIs and how to use them consistently across different boards.

General

Pinout

Each BSP defines a set of macros for default pin assignments used by its hardware peripherals. These macros allow users to configure or reference standard interfaces like I2C, SPI, LCD, audio, or SD cards easily.

• I2C: BSP_I2C_*
• Display: BSP_LCD_*
• Audio I2S: BSP_I2S_*
• USB: BSP_USB_*
• SD Card (MMC): BSP_SD_*
• SD Card (SPI): BSP_SD_SPI_*

[!NOTE] Not all boards support all interfaces. You should always check if the related capability macro (e.g., BSP_CAPS_SDCARD) is defined.

I2C

Some devices included in BSPs (e.g., sensors, displays, audio codecs) communicate via the I2C interface. In many cases, I2C is initialized automatically as part of the device setup. However, you can manually initialize or deinitialize the I2C peripheral using the following API:

/* Initialize the default I2C bus used by the BSP */
bsp_i2c_init();

...

/* Deinitialize the I2C bus */
bsp_i2c_deinit();

If you need direct access to the initialized I2C bus (e.g., to communicate with an external peripheral not handled by the BSP), you can retrieve the I2C bus handle:

i2c_master_bus_handle_t i2c = bsp_i2c_get_handle();

[!NOTE] The BSP ensures that I2C initialization is performed only once, even if called multiple times. This helps avoid conflicts when multiple components rely on the same I2C bus.

ADC

Some devices included in BSPs (such as buttons, battery monitoring, etc.) use the ADC peripheral. In most cases, the ADC is automatically initialized as part of the specific device setup. However, you can manually initialize the ADC using the following API:

/* Initialize the ADC peripheral */
bsp_adc_initialize();

If you need direct access to the ADC instance (e.g., for custom measurements), you can retrieve the handle:

adc_oneshot_unit_handle_t adc = bsp_adc_get_handle();

[!NOTE] The BSP ensures the ADC is initialized only once, even if bsp_adc_initialize() is called multiple times.

Features

Some boards support enabling or disabling specific hardware features (such as LCD, SD card, camera, etc.) to reduce power consumption or manage shared resources. The BSP provides a unified API to control these features:

/* Enable the LCD feature */
bsp_feature_enable(BSP_FEATURE_LCD, true);

/* Disable the speaker to reduce power usage */
bsp_feature_enable(BSP_FEATURE_SPEAKER, false);

Supported feature flags (may vary depending on the board):

• BSP_FEATURE_LCD - Display module
• BSP_FEATURE_TOUCH - Touch controller
• BSP_FEATURE_SD - SD card interface
• BSP_FEATURE_SPEAKER- Audio speaker
• BSP_FEATURE_BATTERY - Battery monitoring
• BSP_FEATURE_VIBRATION - Vibration motor

[!NOTE] Not all BSPs support feature toggling, and some features may not be available or controllable via this API. Always check the BSP header or documentation for supported features.

[!TIP] Disabling unused features can help reduce power consumption, especially in battery-powered applications.

Identification

Each BSP defines an identifier macro in the form of BSP_BOARD_*.

Board Name API Reference

Macros

Type	Name
define	BSP_BOARD_ESP32_LYRAT

:1234: Capabilities

Each BSP defines a set of capability macros that indicate which features are supported. The list may look like this. You can use these macros to conditionally compile code depending on feature availability.

Capabilities API Reference

Macros

Type	Name
define	BSP_CAPS_AUDIO 1
define	BSP_CAPS_AUDIO_MIC 1
define	BSP_CAPS_AUDIO_SPEAKER 1
define	BSP_CAPS_BUTTONS 1
define	BSP_CAPS_DISPLAY 0
define	BSP_CAPS_IMU 0
define	BSP_CAPS_LED 1
define	BSP_CAPS_SDCARD 1
define	BSP_CAPS_TOUCH 0

I2C API Reference

Functions

Type	Name
esp_err_t	bsp_i2c_deinit (void) Deinit I2C driver and free its resources.
i2c_master_bus_handle_t	bsp_i2c_get_handle (void) Get I2C driver handle.
esp_err_t	bsp_i2c_init (void) Init I2C driver.

Macros

Type	Name
define	BSP_I2C_NUM CONFIG_BSP_I2C_NUM
define	BSP_I2C_SCL (GPIO_NUM_23)
define	BSP_I2C_SDA (GPIO_NUM_18)

Functions Documentation

function bsp_i2c_deinit

Deinit I2C driver and free its resources.

esp_err_t bsp_i2c_deinit (
    void
) 

Returns:

• ESP_OK On success
• ESP_ERR_INVALID_ARG I2C parameter error

  function bsp_i2c_get_handle

Get I2C driver handle.

i2c_master_bus_handle_t bsp_i2c_get_handle (
    void
) 

Returns:

• I2C handle

  function bsp_i2c_init

Init I2C driver.

esp_err_t bsp_i2c_init (
    void
) 

Returns:

• ESP_OK On success
• ESP_ERR_INVALID_ARG I2C parameter error
• ESP_FAIL I2C driver installation error

:floppy_disk: SD Card and SPIFFS

SPIFFS Initialization / Deinitialization

Each BSP provides a simple API for mounting and unmounting the SPI Flash File System (SPIFFS).

/* Mount SPIFFS to the virtual file system */
bsp_spiffs_mount();

/* ... perform file operations ... */

/* Unmount SPIFFS from the virtual file system */
bsp_spiffs_unmount();

SD Card Initialization / Deinitialization

The BSP offers a flexible API for working with SD cards. In addition to the default mount and unmount functions, you can also use a configuration structure or access preconfigured host and slot structures.

Mount with Default Configuration

/* Mount microSD card to the virtual file system */
bsp_sdcard_mount();

/* ... perform file operations ... */

/* Unmount microSD card */
bsp_sdcard_unmount();

Mount with Custom Configuration

Some BSPs allow selecting between SDMMC and SPI interfaces for the SD card. Use the appropriate API function based on your hardware:

bsp_sdcard_cfg_t cfg = {0};
/* Mount SD card using SDMMC interface */
bsp_sdcard_sdmmc_mount(&cfg);

or

bsp_sdcard_cfg_t cfg = {0};
/* Mount SD card using SPI interface */
bsp_sdcard_sdspi_mount(&cfg)

[!NOTE] Not all BSPs support both SDMMC and SPI modes. Check the board documentation to see which interfaces are available. If an unsupported interface is used, the API will return ESP_ERR_NOT_SUPPORTED error.

After Mounting

Once the SD card or SPIFFS is mounted, you can use standard file I/O functions (fopen, fread, fwrite, fclose, etc.) provided by ESP-IDF’s VFS (Virtual File System).

To print basic SD card information (after mounting), you can use:

sdmmc_card_t *sdcard = bsp_sdcard_get_handle();
sdmmc_card_print_info(stdout, sdcard);

[!TIP] The bsp_sdcard_get_handle() function returns a pointer to the sdmmc_card_t structure, which contains detailed information about the connected SD card.

SD Card and SPIFFS API Reference

Structures and Types

Type	Name
struct	bsp_sdcard_cfg_t BSP SD card configuration structure.

Functions

Type	Name
sdmmc_card_t *	bsp_sdcard_get_handle (void) Get SD card handle.
void	bsp_sdcard_get_sdmmc_host (const int slot, sdmmc_host_t *config) Get SD card MMC host config.
void	bsp_sdcard_get_sdspi_host (const int slot, sdmmc_host_t *config) Get SD card SPI host config.
esp_err_t	bsp_sdcard_mount (void) Mount microSD card to virtual file system.
void	bsp_sdcard_sdmmc_get_slot (const int slot, sdmmc_slot_config_t *config) Get SD card MMC slot config.
esp_err_t	bsp_sdcard_sdmmc_mount (bsp_sdcard_cfg_t *cfg) Mount microSD card to virtual file system (MMC mode)
void	bsp_sdcard_sdspi_get_slot (const spi_host_device_t spi_host, sdspi_device_config_t *config) Get SD card SPI slot config.
esp_err_t	bsp_sdcard_sdspi_mount (bsp_sdcard_cfg_t *cfg) Mount microSD card to virtual file system (SPI mode)
esp_err_t	bsp_sdcard_unmount (void) Unmount microSD card from virtual file system.
esp_err_t	bsp_spiffs_mount (void) Mount SPIFFS to virtual file system.
esp_err_t	bsp_spiffs_unmount (void) Unmount SPIFFS from virtual file system.

Macros

Type	Name
define	BSP_SDSPI_HOST (SDSPI_DEFAULT_HOST)
define	BSP_SD_CLK (GPIO_NUM_14)
define	BSP_SD_CMD (GPIO_NUM_15)
define	BSP_SD_D0 (GPIO_NUM_2)
define	BSP_SD_MOUNT_POINT CONFIG_BSP_SD_MOUNT_POINT
define	BSP_SD_SPI_CLK (GPIO_NUM_14)
define	BSP_SD_SPI_CS (GPIO_NUM_13)
define	BSP_SD_SPI_MISO (GPIO_NUM_2)
define	BSP_SD_SPI_MOSI (GPIO_NUM_15)
define	BSP_SPIFFS_MOUNT_POINT CONFIG_BSP_SPIFFS_MOUNT_POINT

Structures and Types Documentation

struct bsp_sdcard_cfg_t

BSP SD card configuration structure.

Variables:

• sdmmc_host_t * host

• const esp_vfs_fat_sdmmc_mount_config_t * mount

• const sdmmc_slot_config_t * sdmmc

• const sdspi_device_config_t * sdspi

• union bsp_sdcard_cfg_t slot

Functions Documentation

function bsp_sdcard_get_handle

Get SD card handle.

sdmmc_card_t * bsp_sdcard_get_handle (
    void
) 

Returns:

SD card handle

function bsp_sdcard_get_sdmmc_host

Get SD card MMC host config.

void bsp_sdcard_get_sdmmc_host (
    const int slot,
    sdmmc_host_t *config
) 

Parameters:

• slot SD card slot
• config Structure which will be filled

  function bsp_sdcard_get_sdspi_host

Get SD card SPI host config.

void bsp_sdcard_get_sdspi_host (
    const int slot,
    sdmmc_host_t *config
) 

Parameters:

• slot SD card slot
• config Structure which will be filled

  function bsp_sdcard_mount

Mount microSD card to virtual file system.

esp_err_t bsp_sdcard_mount (
    void
) 

Returns:

• ESP_OK on success
• ESP_ERR_INVALID_STATE if esp_vfs_fat_sdmmc_mount was already called
• ESP_ERR_NO_MEM if memory cannot be allocated
• ESP_FAIL if partition cannot be mounted
• other error codes from SDMMC or SPI drivers, SDMMC protocol, or FATFS drivers

  function bsp_sdcard_sdmmc_get_slot

Get SD card MMC slot config.

void bsp_sdcard_sdmmc_get_slot (
    const int slot,
    sdmmc_slot_config_t *config
) 

Parameters:

• slot SD card slot
• config Structure which will be filled

  function bsp_sdcard_sdmmc_mount

Mount microSD card to virtual file system (MMC mode)

esp_err_t bsp_sdcard_sdmmc_mount (
    bsp_sdcard_cfg_t *cfg
) 

Parameters:

• cfg SD card configuration

Returns:

• ESP_OK on success
• ESP_ERR_INVALID_STATE if esp_vfs_fat_sdmmc_mount was already called
• ESP_ERR_NO_MEM if memory cannot be allocated
• ESP_FAIL if partition cannot be mounted
• other error codes from SDMMC or SPI drivers, SDMMC protocol, or FATFS drivers

  function bsp_sdcard_sdspi_get_slot

Get SD card SPI slot config.

void bsp_sdcard_sdspi_get_slot (
    const spi_host_device_t spi_host,
    sdspi_device_config_t *config
) 

Parameters:

• spi_host SPI host ID
• config Structure which will be filled

  function bsp_sdcard_sdspi_mount

Mount microSD card to virtual file system (SPI mode)

esp_err_t bsp_sdcard_sdspi_mount (
    bsp_sdcard_cfg_t *cfg
) 

Parameters:

• cfg SD card configuration

Returns:

• ESP_OK on success
• ESP_ERR_INVALID_STATE if esp_vfs_fat_sdmmc_mount was already called
• ESP_ERR_NO_MEM if memory cannot be allocated
• ESP_FAIL if partition cannot be mounted
• other error codes from SDMMC or SPI drivers, SDMMC protocol, or FATFS drivers

  function bsp_sdcard_unmount

Unmount microSD card from virtual file system.

esp_err_t bsp_sdcard_unmount (
    void
) 

Returns:

• ESP_OK on success
• ESP_ERR_NOT_FOUND if the partition table does not contain FATFS partition with given label
• ESP_ERR_INVALID_STATE if esp_vfs_fat_spiflash_mount was already called
• ESP_ERR_NO_MEM if memory can not be allocated
• ESP_FAIL if partition can not be mounted
• other error codes from wear levelling library, SPI flash driver, or FATFS drivers

  function bsp_spiffs_mount

Mount SPIFFS to virtual file system.

esp_err_t bsp_spiffs_mount (
    void
) 

Returns:

• ESP_OK on success
• ESP_ERR_INVALID_STATE if esp_vfs_spiffs_register was already called
• ESP_ERR_NO_MEM if memory can not be allocated
• ESP_FAIL if partition can not be mounted
• other error codes

  function bsp_spiffs_unmount

Unmount SPIFFS from virtual file system.

esp_err_t bsp_spiffs_unmount (
    void
) 

Returns:

• ESP_OK on success
• ESP_ERR_NOT_FOUND if the partition table does not contain SPIFFS partition with given label
• ESP_ERR_INVALID_STATE if esp_vfs_spiffs_unregister was already called
• ESP_ERR_NO_MEM if memory can not be allocated
• ESP_FAIL if partition can not be mounted
• other error codes

:musical_note: Audio

Initialization

Before using speaker or microphone features, the audio codec must be initialized.

/* Initialize the speaker codec */
esp_codec_dev_handle_t spk_codec_dev = bsp_audio_codec_speaker_init();

/* Initialize the microphone codec */
esp_codec_dev_handle_t mic_codec_dev = bsp_audio_codec_microphone_init();

After initialization, the esp_codec_dev API can be used to control playback and recording.

[!NOTE] Some BSPs may only support playback (speaker) or only input (microphone). Use the capability macros (BSP_CAPS_AUDIO, BSP_CAPS_AUDIO_SPEAKER, BSP_CAPS_AUDIO_MIC) to check supported features.

Example of audio usage

Speaker

Below is an example of audio playback using the speaker (source data not included):

/* Set volume to 50% */
esp_codec_dev_set_out_vol(spk_codec_dev, 50);

/* Define audio format */
esp_codec_dev_sample_info_t fs = {
    .sample_rate = wav_header.sample_rate,
    .channel = wav_header.num_channels,
    .bits_per_sample = wav_header.bits_per_sample,
};
/* Open speaker stream */
esp_codec_dev_open(spk_codec_dev, &fs);

...
/* Play audio data */
esp_codec_dev_write(spk_codec_dev, wav_bytes, wav_bytes_len);
...

/* Close stream when done */
esp_codec_dev_close(spk_codec_dev);

[!TIP] Audio data must be in raw PCM format. Use a decoder if playing compressed formats (e.g., WAV, MP3).

Microphone

Below is an example of recording audio using the microphone (destination buffer not included):

/* Set input gain (optional) */
esp_codec_dev_set_in_gain(mic_codec_dev, 42.0);

/* Define audio format */
esp_codec_dev_sample_info_t fs = {
    .sample_rate = 16000,
    .channel = 1,
    .bits_per_sample = 16,
};
/* Open microphone stream */
esp_codec_dev_open(mic_codec_dev, &fs);

/* Read recorded data */
esp_codec_dev_read(mic_codec_dev, recording_buffer, BUFFER_SIZE)

...

/* Close stream when done */
esp_codec_dev_close(mic_codec_dev);

Audio API Reference

Functions

Type	Name
esp_codec_dev_handle_t	bsp_audio_codec_microphone_init (void) Initialize microphone codec device.
esp_codec_dev_handle_t	bsp_audio_codec_speaker_init (void) Initialize speaker codec device.
const audio_codec_data_if_t *	bsp_audio_get_codec_itf (void) Get codec I2S interface (initialized in bsp_audio_init)
esp_err_t	bsp_audio_init (const i2s_std_config_t *i2s_config) Init audio.

Macros

Type	Name
define	BSP_I2S_DOUT (GPIO_NUM_26)
define	BSP_I2S_DSIN (GPIO_NUM_35)
define	BSP_I2S_LCLK (GPIO_NUM_25)
define	BSP_I2S_MCLK (GPIO_NUM_0)
define	BSP_I2S_SCLK (GPIO_NUM_5)
define	BSP_POWER_AMP_IO (GPIO_NUM_21)

Functions Documentation

function bsp_audio_codec_microphone_init

Initialize microphone codec device.

esp_codec_dev_handle_t bsp_audio_codec_microphone_init (
    void
) 

Returns:

Pointer to codec device handle or NULL when error occurred

function bsp_audio_codec_speaker_init

Initialize speaker codec device.

esp_codec_dev_handle_t bsp_audio_codec_speaker_init (
    void
) 

Returns:

Pointer to codec device handle or NULL when error occurred

function bsp_audio_get_codec_itf

Get codec I2S interface (initialized in bsp_audio_init)

const audio_codec_data_if_t * bsp_audio_get_codec_itf (
    void
) 

Returns:

• Pointer to codec I2S interface handle or NULL when error occurred

  function bsp_audio_init

Init audio.

esp_err_t bsp_audio_init (
    const i2s_std_config_t *i2s_config
) 

Note:

There is no deinit audio function. Users can free audio resources by calling i2s_del_channel()

Warning:

The type of i2s_config param is depending on IDF version.

Parameters:

• i2s_config I2S configuration. Pass NULL to use default values (Mono, duplex, 16bit, 22050 Hz)

Returns:

• ESP_OK On success
• ESP_ERR_NOT_SUPPORTED The communication mode is not supported on the current chip
• ESP_ERR_INVALID_ARG NULL pointer or invalid configuration
• ESP_ERR_NOT_FOUND No available I2S channel found
• ESP_ERR_NO_MEM No memory for storing the channel information
• ESP_ERR_INVALID_STATE This channel has not initialized or already started

:radio_button: Buttons

Most boards include one or more user buttons. The BSP provides a simple API to initialize and use them. Internally, it utilizes the button component for event handling and debouncing.

/* Initialize all available buttons */
button_handle_t btns[BSP_BUTTON_NUM] = {NULL};
bsp_iot_button_create(btns, NULL, BSP_BUTTON_NUM);

/* Register a callback for button press */
for (int i = 0; i < BSP_BUTTON_NUM; i++) {
    iot_button_register_cb(btns[i], BUTTON_PRESS_DOWN, NULL, btn_handler, (void *) i);
}

/* Called on button press */
static void btn_handler(void *button_handle, void *usr_data)
{
    int button_index = (int)usr_data;
    ESP_LOGI(TAG, "Button %d pressed", button_index);
}

Notes:

• BSP_BUTTON_NUM defines the number of available buttons on the board

• Instead of relying on a numeric index, you can use the bsp_button_t structure defined in the BSP header to reference buttons by name (e.g., BSP_BUTTON_MUTE, BSP_BUTTON_MAIN, BSP_BUTTON_BOOT, etc.)

• The callback can be registered for different button events, such as BUTTON_PRESS_DOWN, BUTTON_PRESS_UP, or BUTTON_LONG_PRESS_START, BUTTON_DOUBLE_CLICK, …

• Button features (e.g. long-press support, active level) are configured automatically by the BSP.

Buttons API Reference

Structures and Types

Type	Name
enum	bsp_button_t

Functions

Type	Name
esp_err_t	bsp_iot_button_create (button_handle_t btn_array, int *btn_cnt, int btn_array_size) Initialize all buttons.

Macros

Type	Name
define	BSP_BUTTON_MODE_IO (GPIO_NUM_39)
define	BSP_BUTTON_PLAY_TOUCH (TOUCH_PAD_NUM8)
define	BSP_BUTTON_REC_IO (GPIO_NUM_36)
define	BSP_BUTTON_SET_TOUCH (TOUCH_PAD_NUM9)
define	BSP_BUTTON_VOLDOWN_TOUCH (TOUCH_PAD_NUM4)
define	BSP_BUTTON_VOLUP_TOUCH (TOUCH_PAD_NUM7)

Structures and Types Documentation

enum bsp_button_t

enum bsp_button_t {
    BSP_BUTTON_REC = 0,
    BSP_BUTTON_MODE,
    BSP_BUTTON_PLAY,
    BSP_BUTTON_SET,
    BSP_BUTTON_VOLUP,
    BSP_BUTTON_VOLDOWN,
    BSP_BUTTON_NUM
};

Functions Documentation

function bsp_iot_button_create

Initialize all buttons.

esp_err_t bsp_iot_button_create (
    button_handle_t btn_array,
    int *btn_cnt,
    int btn_array_size
) 

Returned button handlers must be used with espressif/button component API

Note:

For LCD panel button which is defined as BSP_BUTTON_MAIN, bsp_display_start should be called before call this function.

Parameters:

• btn_array Output button array
• btn_cnt Number of button handlers saved to btn_array, can be NULL
• btn_array_size Size of output button array. Must be at least BSP_BUTTON_NUM

Returns:

• ESP_OK All buttons initialized
• ESP_ERR_INVALID_ARG btn_array is too small or NULL
• ESP_FAIL Underlaying iot_button_create failed

:bulb: LEDs

LEDs are handled similarly to buttons in BSP. The BSP uses the led_indicator component, which provides simple control over LED states and built-in effects such as blinking, breathing, and more. It also supports addressable RGB LEDs.

/* Initialize all LEDs */
bsp_led_indicator_create(leds, NULL, BSP_LED_NUM);

/* Set color of the first LED (for addressable RGB LEDs only) */
led_indicator_set_rgb(leds[0], SET_IRGB(0, 0x00, 0x64, 0x64));

/*
Start a predefined LED effect:
- BSP_LED_ON
- BSP_LED_OFF
- BSP_LED_BLINK_FAST
- BSP_LED_BLINK_SLOW
- BSP_LED_BREATHE_FAST
- BSP_LED_BREATHE_SLOW
*/
led_indicator_start(leds[0], BSP_LED_BREATHE_SLOW);

Notes:

• BSP_LED_NUM defines the total number of available LEDs on the board
• LEDs are automatically configured by the BSP (no need to set GPIO or direction manually)

Leds API Reference

Structures and Types

Type	Name
enum	bsp_led_t
typedef enum bsp_led_t	bsp_led_t

Functions

Type	Name
esp_err_t	bsp_led_set (const bsp_led_t led_io, const bool on) Turn LED on/off.
esp_err_t	bsp_leds_init (void) Set LED’s GPIOs as output push-pull.

Structures and Types Documentation

enum bsp_led_t

enum bsp_led_t {
    BSP_LED_GREEN = GPIO_NUM_22
};

typedef bsp_led_t

typedef enum bsp_led_t bsp_led_t;

Functions Documentation

function bsp_led_set

Turn LED on/off.

esp_err_t bsp_led_set (
    const bsp_led_t led_io,
    const bool on
) 

Parameters:

• led_io LED io
• on Switch LED on/off

Returns:

• ESP_OK Success
• ESP_ERR_INVALID_ARG Parameter error

  function bsp_leds_init

Set LED’s GPIOs as output push-pull.

esp_err_t bsp_leds_init (
    void
) 

Returns:

• ESP_OK Success
• ESP_ERR_INVALID_STATE Could not init IO expander
• ESP_ERR_INVALID_ARG Parameter error

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