Thanks but I intend to develop the code from scratch.

My first try is the following but the dma_callback is not executed.

I appreciate any help, thanks.

`
// "ESP32S3 Dev Module" 2.0.9

#include <esp_rom_gpio.h>
#include <driver/periph_ctrl.h>
#include <esp_private/gdma.h>
#include <hal/dma_types.h>
#include <soc/lcd_cam_struct.h>

#define dmabuf_camrx_len 1470 // DMA camera RX buffer size
gdma_channel_handle_t dma_camrx_chan; // CAM RX DMA channel
uint8_t dmabuf_camrx[dmabuf_camrx_len]; // DMA RX camera buffer
dma_descriptor_t desc; // DMA RX camera descriptor

#define pclk_pin 13
#define xclk_pin 21
#define href_pin 46
#define d2_pin 40
#define d3_pin 39
#define d4_pin 38
#define d5_pin 37
#define d6_pin 36
#define d7_pin 5
#define d8_pin 45
#define d9_pin 47

// End of DMA transfer callback
static IRAM_ATTR bool dma_callback(gdma_channel_handle_t dma_camrx_chan, gdma_event_data_t *event_data, void *user_data) {
Serial.println("End of DMA transfer");
return true;
}

void setup() {
Serial.begin(115200);

// LCD_CAM peripheral enable and reset
periph_module_enable(PERIPH_LCD_CAM_MODULE);
periph_module_reset(PERIPH_LCD_CAM_MODULE);

////////// Reset CAM bus
LCD_CAM.cam_ctrl1.cam_reset = 1;

// CAM module registers configuration
LCD_CAM.cam_ctrl.cam_clk_sel = 1; // XTAL_CLK source (40MHz)
LCD_CAM.cam_ctrl.cam_clkm_div_num = 2; // CAM_CLK_IDX = 20MHz
LCD_CAM.cam_ctrl.cam_clkm_div_b = 0;
LCD_CAM.cam_ctrl.cam_clkm_div_a = 0;
LCD_CAM.cam_ctrl1.cam_vh_de_mode_en = 1;
LCD_CAM.cam_ctrl.cam_update = 1;

// Route CAM signals to GPIO pins
const struct {
uint32_t pin;
uint8_t signal;
} mux[] = {
{ d2_pin, CAM_DATA_IN0_IDX }, { d3_pin, CAM_DATA_IN1_IDX }, { d4_pin, CAM_DATA_IN2_IDX },
{ d5_pin, CAM_DATA_IN3_IDX }, { d6_pin, CAM_DATA_IN4_IDX }, { d7_pin, CAM_DATA_IN5_IDX },
{ d8_pin, CAM_DATA_IN6_IDX }, { d9_pin, CAM_DATA_IN7_IDX }, { pclk_pin, CAM_PCLK_IDX },
{ href_pin, CAM_H_ENABLE_IDX },
{ GPIO_MATRIX_CONST_ONE_INPUT, CAM_H_SYNC_IDX }, { GPIO_MATRIX_CONST_ONE_INPUT, CAM_V_SYNC_IDX }
};
for (int i = 0; i < 12; i++) {
if (mux[i].pin != GPIO_MATRIX_CONST_ONE_INPUT) {
esp_rom_gpio_pad_select_gpio(mux[i].pin);
}
esp_rom_gpio_connect_in_signal(mux[i].pin, mux[i].signal, false);
}
esp_rom_gpio_pad_select_gpio(xclk_pin);
esp_rom_gpio_pad_set_drv(xclk_pin, 3);
esp_rom_gpio_connect_out_signal(xclk_pin, CAM_CLK_IDX, false, false);

// GDMA descriptor
desc.dw0.owner = DMA_DESCRIPTOR_BUFFER_OWNER_DMA;
desc.dw0.suc_eof = 1; // Last descriptor
desc.dw0.size = dmabuf_camrx_len;
desc.buffer = dmabuf_camrx;
desc.next = NULL;

// Allocate DMA channel and connect it to the CAM peripheral
gdma_channel_alloc_config_t dma_camrx_chan_config = {
.sibling_chan = NULL,
.direction = GDMA_CHANNEL_DIRECTION_RX,
.flags = {
.reserve_sibling = 0
}
};
gdma_new_channel(&dma_camrx_chan_config, &dma_camrx_chan);
gdma_connect(dma_camrx_chan, GDMA_MAKE_TRIGGER(GDMA_TRIG_PERIPH_CAM, 0));
gdma_strategy_config_t strategy_config = {
.owner_check = false,
.auto_update_desc = false
};
gdma_apply_strategy(dma_camrx_chan, &strategy_config);

// Enable DMA transfer callback
gdma_rx_event_callbacks_t rx_cbs = {
.on_recv_eof = dma_callback
};
gdma_register_rx_event_callbacks(dma_camrx_chan, &rx_cbs, NULL);

// Here OV5640 camera configuration code using I2C
//////////////////////
// Camera interface is ok checked with a logic analyzer (xclk, pclk, vsync and href)

delay(50);

gdma_reset(dma_camrx_chan); // Reset DMA to known state
LCD_CAM.cam_ctrl.cam_update = 1; // Update registers
LCD_CAM.cam_ctrl1.cam_afifo_reset = 1;

gdma_start(dma_camrx_chan, (intptr_t)&desc); // Start DMA

LCD_CAM.cam_ctrl1.cam_start = 1; // Trigger CAM DMA transfer
}

void loop() {
delay(10);
}
`

The camera driver is public and open source, I suggest you look there. It is not a basic task to get it going and here is not the place to discuss such topics really. What is the reason not to use the already developed driver?

Hello, I have reviewed the CameraWebServer.ino file and I think it does not support my requirements.

My goal is to stream the video from the camera by sending UDP Multicast datagrams with the minimum delay.

I managed to do this years ago in an ESP32 using the I2S peripheral and DMA , based on esp32-camera.

Now I want to achieve the same in an ESP32-S3 using the new LCD_CAM peripheral and GDMA, for which
I am basing myself on https://blog.adafruit.com/2022/06/21/esp32uesday-more-s3-lcd-peripheral-hacking-with-code/

Regards.

how you transfer is outside of the question. The driver provides you with a good way to grab a frame as soon as it's ready. What you do wit it from then on it does not matter. Your answers is outside of the camera driver and I strongly suggest that you use it.

ok, I will use the camera driver, thanks.