# 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 = CAM_CTLR_COLOR_RAW8,
        .output_data_color_type = CAM_CTLR_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_CAM_CTLR_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_CAM_CTLR_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.

## Application Examples

- peripherals/camera/mipi_isp_dsi demonstrates how to use the `esp_driver_cam` component to capture signals from a MIPI CSI camera sensor via the ISP module and display it on a LCD screen via a DSI interface.

- peripherals/camera/dvp_isp_dsi demonstrates how to use the `esp_driver_cam` component to capture signals from a DVP camera sensor via the ISP module and display it on a LCD screen via a DSI interface.

## 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.

  参数:

    handle -- [in] ESP CAM controller handle

  返回:

    - 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.

  参数:

    handle -- [in] ESP CAM controller handle

  返回:

    - 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.

  参数:

    handle -- [in] ESP CAM controller handle

  返回:

    - 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.

  参数:

    handle -- [in] ESP CAM controller handle

  返回:

    - 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.

  参数:

    - handle -- [in] ESP CAM controller handle

    - trans -- [in] ESP CAM controller transaction type

    - timeout_ms -- [in] Timeout in ms

  返回:

    - 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.

  参数:

    handle -- [in] ESP CAM controller handle

  返回:

    - 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.

  参数:

    - handle -- [in] ESP CAM controller handle

    - cbs -- [in] ESP CAM controller event callbacks

    - user_data -- [in] User data

  返回:

    - 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.

  备注

  Generally, data in internal buffer is ready when `on_trans_finished` event

  参数:

    - 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

  返回:

    - 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.

  参数:

    - handle -- [in] ESP CAM controller handle

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

  返回:

    - 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

### Macros

ESP_CAM_CTLR_MAX_DELAY

  ESP CAM controller max timeout value.

### 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.

  参数:

    - config -- [in] CSI controller configurations

    - ret_handle -- [out] Returned ESP CAM controller handle

  返回:

    - 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.

  cam_ctlr_color_t input_data_color_type

    Input color type.

  cam_ctlr_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.

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