Camera Controller Driver

Introduction

ESP32-P4 has the following hardware that is intended for communication with external camera sensor:

MIPI Camera Serial Interface (CSI)

The Camera Controller Driver is designed for this hardware peripheral.

Functional Overview

Resource Allocation - covers how to allocate camera controller instances with properly set of configurations. It also covers how to recycle the resources when they are no longer needed.
Enable and disable a camera controller - covers how to enable and disable a camera controller.
Start and stop a camera controller - covers how to start and stop a camera controller.
Receive from a camera sensor or something else - covers how to receive camera signal from a sensor or something else.
Register callback - covers how to hook user specific code to camera controller driver event callback function.
Thread Safety - lists which APIs are guaranteed to be thread safe by the driver.
Kconfig Options - lists the supported Kconfig options that can bring different effects to the driver.
IRAM SAFE - describes tips on how to make the CSI interrupt and control functions work better along with a disabled cache.

Resource Allocation

Install Camera Controller Driver

A Camera Controller Driver can be implemented by the CSI peripheral, which requires the configuration that specified by esp_cam_ctlr_csi_config_t.

If the configurations in esp_cam_ctlr_csi_config_t is specified, users can call esp_cam_new_csi_ctlr() to allocate and initialize a CSI camera controller handle. This function will return an CSI camera controller handle if it runs correctly. You can take following code as reference.

esp_cam_ctlr_csi_config_t csi_config = {
    .ctlr_id = 0,
    .h_res = MIPI_CSI_DISP_HSIZE,
    .v_res = MIPI_CSI_DISP_VSIZE_640P,
    .lane_bit_rate_mbps = MIPI_CSI_LANE_BITRATE_MBPS,
    .input_data_color_type = MIPI_CSI_COLOR_RAW8,
    .output_data_color_type = MIPI_CSI_COLOR_RGB565,
    .data_lane_num = 2,
    .byte_swap_en = false,
    .queue_items = 1,
};
esp_cam_ctlr_handle_t handle = NULL;
ESP_ERROR_CHECK(esp_cam_new_csi_ctlr(&csi_config, &handle));

Uninstall Camera Controller Driver

If a previously installed Camera Controller Driver is no longer needed, it's recommended to recycle the resource by calling esp_cam_ctlr_del(), so that to release the underlying hardware.

Enable and Disable Camera Controller Driver

Before starting camera controller operation, you need to enable the camera controller controller first, by calling esp_cam_ctlr_enable(). This function:

Switches the driver state from init to enable.

ESP_ERROR_CHECK(esp_cam_ctlr_enable(handle));

Calling esp_cam_ctlr_disable() does the opposite, that is, put the driver back to the init state.

ESP_ERROR_CHECK(esp_cam_ctlr_disable(handle));

Start and Stop Camera Controller Driver

Before receiving camera signal from camera sensor, you need to start the Camera Controller Driver first, by calling esp_cam_ctlr_start(). This function:

Switches the driver stat from enable to start

ESP_ERROR_CHECK(esp_cam_ctlr_start(handle));

Calling esp_cam_ctlr_stop() does the opposite, that is, put the driver back to the enable state.

ESP_ERROR_CHECK(esp_cam_ctlr_stop(handle));

Receive from A Camera Sensor

Now you can call esp_cam_ctlr_receive() to receive from a camera sensor or something else.

ESP_ERROR_CHECK(esp_cam_ctlr_receive(handle, &my_trans, ESP_CAM_CTLR_MAX_DELAY));

Register Event Callbacks

After the Camera Controller Driver starts receiving, it can generate a specific event dynamically. If you have some functions that should be called when the event happens, please hook your function to the interrupt service routine by calling esp_cam_ctlr_register_event_callbacks(). All supported event callbacks are listed in esp_cam_ctlr_evt_cbs_t:

esp_cam_ctlr_evt_cbs_t::on_get_new_trans sets a callback function when the Camera Controller Driver gets a new transaction which is passed from esp_cam_ctlr_receive(). As this function is called within the ISR context, you must ensure that the function does not attempt to block (e.g., by making sure that only FreeRTOS APIs with ISR suffix are called from within the function).
esp_cam_ctlr_evt_cbs_t::on_trans_finished sets a callback function when the Camera Controller Driver finishes a transaction. As this function is called within the ISR context, you must ensure that the function does not attempt to block (e.g., by making sure that only FreeRTOS APIs with ISR suffix are called from within the function).

Thread Safety

The factory function esp_cam_new_csi_ctlr() and esp_cam_ctlr_del() are guaranteed to be thread safe by the driver, which means, user can call them from different RTOS tasks without protection by extra locks.

Kconfig Options

CONFIG_MIPI_CSI_ISR_IRAM_SAFE controls whether the default ISR handler should be masked when the cache is disabled

IRAM Safe

By default, the CSI interrupt will be deferred when the cache is disabled because of writing or erasing the flash.

There is a Kconfig option CONFIG_MIPI_CSI_ISR_IRAM_SAFE that:

Enables the interrupt being serviced even when the cache is disabled
Places all functions that used by the ISR into IRAM
Places driver object into DRAM (in case it is mapped to PSRAM by accident)

This allows the interrupt to run while the cache is disabled, but comes at the cost of increased IRAM consumption. So user callbacks need to notice that the code and data inside (the callback) should be IRAM-safe or DRAM-safe, when cache is disabled.

API Reference

Header File

components/esp_driver_cam/include/esp_cam_ctlr.h
This header file can be included with:
#include "esp_cam_ctlr.h"
This header file is a part of the API provided by the esp_driver_cam component. To declare that your component depends on esp_driver_cam, add the following to your CMakeLists.txt:
REQUIRES esp_driver_cam
or
PRIV_REQUIRES esp_driver_cam

Functions

esp_err_t esp_cam_ctlr_enable(esp_cam_ctlr_handle_t handle)

Enable ESP CAM controller.

Parameters

handle -- [in] ESP CAM controller handle

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid state

esp_err_t esp_cam_ctlr_start(esp_cam_ctlr_handle_t handle)

Start ESP CAM controller.

Parameters

handle -- [in] ESP CAM controller handle

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid state

esp_err_t esp_cam_ctlr_stop(esp_cam_ctlr_handle_t handle)

Stop ESP CAM controller.

Parameters

handle -- [in] ESP CAM controller handle

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid state

esp_err_t esp_cam_ctlr_disable(esp_cam_ctlr_handle_t handle)

Disable ESP CAM controller.

Parameters

handle -- [in] ESP CAM controller handle

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid state

esp_err_t esp_cam_ctlr_receive(esp_cam_ctlr_handle_t handle, esp_cam_ctlr_trans_t *trans, uint32_t timeout_ms)

Receive data to the given transaction.

Parameters

handle -- [in] ESP CAM controller handle
trans -- [in] ESP CAM controller transaction type
timeout_ms -- [in] Timeout in ms

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid state

esp_err_t esp_cam_ctlr_del(esp_cam_ctlr_handle_t handle)

Delete ESP CAM controller handle.

Parameters

handle -- [in] ESP CAM controller handle

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid state

esp_err_t esp_cam_ctlr_register_event_callbacks(esp_cam_ctlr_handle_t handle, const esp_cam_ctlr_evt_cbs_t *cbs, void *user_data)

Register ESP CAM controller event callbacks.

Parameters

handle -- [in] ESP CAM controller handle
cbs -- [in] ESP CAM controller event callbacks
user_data -- [in] User data

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid state

esp_err_t esp_cam_ctlr_get_frame_buffer(esp_cam_ctlr_handle_t handle, uint32_t fb_num, const void **fb0, ...)

Get ESP CAM controller internal malloced backup buffer(s) addr.

Note

Generally, data in internal buffer is ready when on_trans_finished event

Parameters

handle -- [in] ESP CAM controller handle
fb_num -- [in] Number of frame buffer(s) to get. This value must be the same as the number of the followed fbN parameters
fb0 -- [out] Address of the frame buffer 0 (first frame buffer)
... -- [out] List of other frame buffers if any

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_INVALID_STATE: Invalid driver state

esp_err_t esp_cam_ctlr_get_frame_buffer_len(esp_cam_ctlr_handle_t handle, size_t *ret_fb_len)

Get ESP CAM controller internal backup buffer length.

Parameters

handle -- [in] ESP CAM controller handle
ret_fb_len -- [out] Optional, The size of each frame buffer, in bytes.

Returns

ESP_OK
ESP_ERR_INVALID_ARG: NULL ptr
ESP_ERR_INVALID_STATE: Invalid driver state

Header File

components/esp_driver_cam/include/esp_cam_ctlr_types.h
This header file can be included with:
#include "esp_cam_ctlr_types.h"
This header file is a part of the API provided by the esp_driver_cam component. To declare that your component depends on esp_driver_cam, add the following to your CMakeLists.txt:
REQUIRES esp_driver_cam
or
PRIV_REQUIRES esp_driver_cam

Structures

struct esp_cam_ctlr_trans_t

ESP CAM controller transaction type.

Public Members

void *buffer: Transaction buffer.

size_t buflen: Len of the transaction buffer.

size_t received_size: Received size, this received_size will be written by the driver, indicating the real received size.

struct esp_cam_ctlr_evt_cbs_t

ESP CAM controller event callbacks.

Public Members

bool (*on_get_new_trans)(esp_cam_ctlr_handle_t handle, esp_cam_ctlr_trans_t *trans, void *user_data)

On get new transaction callback.

Param handle: [in] ESP CAM controller handle
Param trans: [in] New transaction
Param user_data: [in] User registered data
Return: Whether a high priority task is woken up by this function

bool (*on_trans_finished)(esp_cam_ctlr_handle_t handle, esp_cam_ctlr_trans_t *trans, void *user_data)

On transaction finish callback.

Param handle: [in] ESP CAM controller handle
Param trans: [out] Finished transaction
Param user_data: [in] User registered data
Return: Whether a high priority task is woken up by this function

Type Definitions

typedef struct esp_cam_ctlr_t *esp_cam_ctlr_handle_t: ESP CAM controller handle.

Header File

components/esp_driver_cam/csi/include/esp_cam_ctlr_csi.h
This header file can be included with:
#include "esp_cam_ctlr_csi.h"
This header file is a part of the API provided by the esp_driver_cam component. To declare that your component depends on esp_driver_cam, add the following to your CMakeLists.txt:
REQUIRES esp_driver_cam
or
PRIV_REQUIRES esp_driver_cam

Functions

esp_err_t esp_cam_new_csi_ctlr(const esp_cam_ctlr_csi_config_t *config, esp_cam_ctlr_handle_t *ret_handle)

New ESP CAM CSI controller.

Parameters

config -- [in] CSI controller configurations
ret_handle -- [out] Returned ESP CAM controller handle

Returns

ESP_OK
ESP_ERR_INVALID_ARG: Invalid argument
ESP_ERR_NO_MEM: Out of memory
ESP_ERR_NOT_SUPPORTED: Currently not support modes or types
ESP_ERR_NOT_FOUND: CSI is registered already

Structures

struct esp_cam_ctlr_csi_config_t

ESP CAM CSI controller configurations.

Public Members

int ctlr_id: CSI controller ID.

mipi_csi_phy_clock_source_t clk_src: CSI phy clock source.

uint32_t h_res: Input horizontal resolution, i.e. the number of pixels in a line.

uint32_t v_res: Input vertical resolution, i.e. the number of lines in a frame.

uint8_t data_lane_num: Data lane num.

int lane_bit_rate_mbps: Lane bit rate in Mbps.

mipi_csi_color_t input_data_color_type: Input color type.

mipi_csi_color_t output_data_color_type: Output color type.

int queue_items: Queue items.

uint32_t byte_swap_en: Enable byte swap.

uint32_t bk_buffer_dis: Disable backup buffer.

struct esp_cam_ctlr_csi_config_t::[anonymous] [anonymous]: Boolean Flags.

Macros

ESP_CAM_CTLR_MAX_DELAY: ESP CAM controller max timeout value.

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