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) | :pager: [DISPLAY AND TOUCH](#pager-display-and-touch) | :radio_button: [BUTTONS](#radio_button-buttons) | :bulb: [LEDS](#bulb-leds) | :electric_plug: [USB](#electric_plug-usb) | | :-------------------------: | :-------------------------: | :-------------------------: | :-------------------------: | :-------------------------: | :-------------------------: | :-------------------------: |

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.

[!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):

[!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_C3_LCDKIT

: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 0
define BSP_CAPS_AUDIO_SPEAKER 1
define BSP_CAPS_BUTTONS 0
define BSP_CAPS_DISPLAY 1
define BSP_CAPS_IMU 0
define BSP_CAPS_KNOB 1
define BSP_CAPS_LED 1
define BSP_CAPS_SDCARD 0
define BSP_CAPS_TOUCH 0

: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

Functions

Type Name
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_SPIFFS_MOUNT_POINT CONFIG_BSP_SPIFFS_MOUNT_POINT

Functions Documentation

function bsp_spiffs_mount

Mount SPIFFS to virtual file system.

esp_err_t bsp_spiffs_mount (
    void
)

Returns:

Unmount SPIFFS from virtual file system.

esp_err_t bsp_spiffs_unmount (
    void
)

Returns:

: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_speaker_init (void)
Initialize speaker codec device.
esp_err_t bsp_audio_init (const i2s_pdm_tx_config_t *i2s_config, i2s_chan_handle_t *tx_channel)
Init audio.

Macros

Type Name
define BSP_I2S_CLK (GPIO_NUM_NC)
define BSP_I2S_DOUT (GPIO_NUM_3)

Functions Documentation

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_init

Init audio.

esp_err_t bsp_audio_init (
    const i2s_pdm_tx_config_t *i2s_config,
    i2s_chan_handle_t *tx_channel
)

Note:

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

Parameters:

Returns:

:pager: Display and Touch

Initialization

ESP-BSP provides two ways to initialize the display, touch and LVGL.

Simple method:

/* Initialize display, touch, and LVGL */
lv_display_t display = bsp_display_start();

Configurable method:

bsp_display_cfg_t cfg = {
    .lvgl_port_cfg = ESP_LVGL_PORT_INIT_CONFIG(),   /* See LVGL Port for more info */
    .buffer_size = BSP_LCD_V_RES * BSP_LCD_H_RES,   /* Screen buffer size in pixels */
    .double_buffer = true,                          /* Allocate two buffers if true */
    .flags = {
        .buff_dma = true,                           /* Use DMA-capable LVGL buffer */
        .buff_spiram = false,                       /* Allocate buffer in PSRAM if true */
    }
};
cfg.lvgl_port_cfg.task_stack = 10000;   /* Example: change LVGL task stack size */
/* Initialize display, touch, and LVGL */
lv_display_t display = bsp_display_start_with_config(&cfg);

After initialization, you can use the LVGL API or LVGL Port API.

Initialization without LVGL - NoGLIB BSP

To initialize the LCD without LVGL, use:

esp_lcd_panel_handle_t panel_handle;
esp_lcd_panel_io_handle_t io_handle;
const bsp_display_config_t bsp_disp_cfg = {
    .max_transfer_sz = (BSP_LCD_H_RES * 100) * sizeof(uint16_t),
};
BSP_ERROR_CHECK_RETURN_NULL(bsp_display_new(&bsp_disp_cfg, &panel_handle, &io_handle));

To initialize the LCD touch without LVGL, use:

esp_lcd_touch_handle_t tp;
bsp_touch_new(NULL, &tp);

After initialization, you can use the ESP-LCD API and ESP-LCD Touch API.

Set Brightness

/* Set display brightness to 100% */
bsp_display_backlight_on();

/* Set display brightness to 0% */
bsp_display_backlight_off();

/* Set display brightness to 50% */
bsp_display_brightness_set(50);

[!NOTE] Some boards do not support changing brightness. They return an ESP_ERR_NOT_SUPPORTED error.

LVGL API Usage (only when initialized with LVGL)

All LVGL calls must be protected using lock/unlock:

/* Wait until other tasks finish screen operations */
bsp_display_lock(0);
...
lv_obj_t * screen = lv_disp_get_scr_act(disp_handle);
lv_obj_t * obj = lv_label_create(screen);
...
/* Unlock after screen operations are done */
bsp_display_unlock();

Screen rotation (only when initialized with LVGL)

bsp_display_lock(0);
/* Rotate display to 90 */
bsp_display_rotate(display, LV_DISPLAY_ROTATION_90);
bsp_display_unlock();

[!NOTE] Some LCDs do not support hardware rotation and instead use software rotation, which consumes more memory.

Available constants

Constants like screen resolution, pin configuration, and other options are defined in the BSP header files ({bsp_name}.h, display.h, touch.h). Below are some of the most relevant predefined constants:

Display and Touch API Reference

Structures and Types

Type Name
struct bsp_display_cfg_t
BSP display configuration structure.
struct bsp_display_config_t
BSP display configuration structure.

Functions

Type Name
esp_err_t bsp_display_backlight_off (void)
Turn off display backlight.
esp_err_t bsp_display_backlight_on (void)
Turn on display backlight.
esp_err_t bsp_display_brightness_init (void)
Initialize display’s brightness.
esp_err_t bsp_display_brightness_set (int brightness_percent)
Set display’s brightness.
lv_indev_t * bsp_display_get_input_dev (void)
Get pointer to input device (touch, buttons, …)
bool bsp_display_lock (uint32_t timeout_ms)
Take LVGL mutex.
esp_err_t bsp_display_new (const bsp_display_config_t *config, esp_lcd_panel_handle_t *ret_panel, esp_lcd_panel_io_handle_t *ret_io)
Create new display panel.
void bsp_display_rotate (lv_display_t *disp, lv_disp_rotation_t rotation)
Rotate screen.
lv_display_t * bsp_display_start (void)
Initialize display.
lv_disp_t * bsp_display_start_with_config (const bsp_display_cfg_t *cfg)
Initialize display.
void bsp_display_unlock (void)
Give LVGL mutex.

Macros

Type Name
define BSP_LCD_BACKLIGHT (GPIO_NUM_5)
define BSP_LCD_BIGENDIAN (1)
define BSP_LCD_BITS_PER_PIXEL (16)
define BSP_LCD_COLOR_FORMAT (ESP_LCD_COLOR_FORMAT_RGB565)
define BSP_LCD_COLOR_SPACE (LCD_RGB_ELEMENT_ORDER_BGR)
define BSP_LCD_CS (GPIO_NUM_7)
define BSP_LCD_DATA0 (GPIO_NUM_0)
define BSP_LCD_DC (GPIO_NUM_2)
define BSP_LCD_H_RES (240)
define BSP_LCD_PCLK (GPIO_NUM_1)
define BSP_LCD_PIXEL_CLOCK_HZ (80 * 1000 * 1000)
define BSP_LCD_RST (GPIO_NUM_NC)
define BSP_LCD_SPI_NUM (SPI2_HOST)
define BSP_LCD_V_RES (240)
define ESP_LCD_COLOR_FORMAT_RGB565 (1)
define ESP_LCD_COLOR_FORMAT_RGB888 (2)

Structures and Types Documentation

struct bsp_display_cfg_t

BSP display configuration structure.

Variables:

struct bsp_display_config_t

BSP display configuration structure.

Variables:

Functions Documentation

function bsp_display_backlight_off

Turn off display backlight.

esp_err_t bsp_display_backlight_off (
    void
)

Brightness is controlled with PWM signal to a pin controlling backlight. Brightness must be already initialized by calling bsp_display_brightness_init() orbsp_display_new()

Returns:

Turn on display backlight.

esp_err_t bsp_display_backlight_on (
    void
)

Brightness is controlled with PWM signal to a pin controlling backlight. Brightness must be already initialized by calling bsp_display_brightness_init() orbsp_display_new()

Returns:

Initialize display’s brightness.

esp_err_t bsp_display_brightness_init (
    void
)

Brightness is controlled with PWM signal to a pin controlling backlight.

Returns:

Set display’s brightness.

esp_err_t bsp_display_brightness_set (
    int brightness_percent
)

Brightness is controlled with PWM signal to a pin controlling backlight. Brightness must be already initialized by calling bsp_display_brightness_init() orbsp_display_new()

Parameters:

Returns:

Get pointer to input device (touch, buttons, …)

lv_indev_t * bsp_display_get_input_dev (
    void
)

Note:

The LVGL input device is initialized in bsp_display_start() function.

Returns:

Pointer to LVGL input device or NULL when not initialized

function bsp_display_lock

Take LVGL mutex.

bool bsp_display_lock (
    uint32_t timeout_ms
)

Parameters:

Returns:

true Mutex was taken

Returns:

false Mutex was NOT taken

function bsp_display_new

Create new display panel.

esp_err_t bsp_display_new (
    const bsp_display_config_t *config,
    esp_lcd_panel_handle_t *ret_panel,
    esp_lcd_panel_io_handle_t *ret_io
)

For maximum flexibility, this function performs only reset and initialization of the display. You must turn on the display explicitly by calling esp_lcd_panel_disp_on_off(). The display’s backlight is not turned on either. You can use bsp_display_backlight_on/off(), bsp_display_brightness_set() (on supported boards) or implement your own backlight control.

If you want to free resources allocated by this function, you can use esp_lcd API, ie.:

esp_lcd_panel_del(panel);
esp_lcd_panel_io_del(io);
spi_bus_free(spi_num_from_configuration);

Parameters:

Returns:

Rotate screen.

void bsp_display_rotate (
    lv_display_t *disp,
    lv_disp_rotation_t rotation
)

Display must be already initialized by calling bsp_display_start()

Parameters:

Initialize display.

lv_display_t * bsp_display_start (
    void
)

This function initializes SPI, display controller and starts LVGL handling task. LCD backlight must be enabled separately by calling bsp_display_brightness_set()

Returns:

Pointer to LVGL display or NULL when error occurred

function bsp_display_start_with_config

Initialize display.

lv_disp_t * bsp_display_start_with_config (
    const bsp_display_cfg_t *cfg
)

This function initializes SPI, display controller and starts LVGL handling task. LCD backlight must be enabled separately by calling bsp_display_brightness_set()

Parameters:

Returns:

Pointer to LVGL display or NULL when error occurred

function bsp_display_unlock

Give LVGL mutex.

void bsp_display_unlock (
    void
)

: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:

Buttons API Reference

Structures and Types

Type Name
enum bsp_button_t

Structures and Types Documentation

enum bsp_button_t

enum bsp_button_t {
    BSP_BTN_PRESS = GPIO_NUM_9
};

: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:

Leds API Reference

Functions

Type Name
esp_err_t bsp_led_init ()
Initialize WS2812.
esp_err_t bsp_led_rgb_set (uint8_t r, uint8_t g, uint8_t b)
Set RGB for a specific pixel.

Macros

Type Name
define BSP_RGB_CTRL (GPIO_NUM_8)

Functions Documentation

function bsp_led_init

Initialize WS2812.

esp_err_t bsp_led_init ()

Returns:

Set RGB for a specific pixel.

esp_err_t bsp_led_rgb_set (
    uint8_t r,
    uint8_t g,
    uint8_t b
)

Parameters:

Returns:

:electric_plug: USB

Boards with USB support define macros for USB pins, such as BSP_USB_POS and BSP_USB_NEG, and may also provide control APIs for enabling or disabling USB functionality.

/* Initialize USB in device mode and enable power */
bsp_usb_host_start(BSP_USB_HOST_POWER_MODE_USB_DEV, true);

...
/* Deinitialize and stop USB */
bsp_usb_host_stop();

[!NOTE] Not all BSPs implement USB support or provide power control. Refer to the board’s documentation and the BSP header files for available functions and supported modes.

For more USB-related APIs and configuration options, check the corresponding BSP header files.

USB API Reference

Macros

Type Name
define BSP_USB_NEG (GPIO_NUM_19)
define BSP_USB_POS (GPIO_NUM_20)
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