Add experimental double FPS mode for OV2640

Allows for 52fps@CIF, 26fps@SVGA and 6.5fps@UXGA (unchanged) when XCLK is set to 10MHz

README.md

@@ -44,6 +44,7 @@ This repository hosts ESP32 compatible driver for OV2640 image sensors. Addition
 #define CAM_PIN_PCLK    22
 
 static camera_config_t camera_config = {
+    .pin_pwdn  = CAM_PIN_PWDN,
     .pin_reset = CAM_PIN_RESET,
     .pin_xclk = CAM_PIN_XCLK,
     .pin_sscb_sda = CAM_PIN_SIOD,
@@ -61,7 +62,7 @@ static camera_config_t camera_config = {
     .pin_href = CAM_PIN_HREF,
     .pin_pclk = CAM_PIN_PCLK,
 
-    //XCLK 20MHz or 10MHz
+    //XCLK 20MHz or 10MHz for OV2640 double FPS (Experimental)
     .xclk_freq_hz = 20000000,
     .ledc_timer = LEDC_TIMER_0,
     .ledc_channel = LEDC_CHANNEL_0,

driver/camera.c

@@ -884,6 +884,7 @@ esp_err_t camera_probe(const camera_config_t* config, camera_model_t* out_camera
         return ESP_ERR_CAMERA_NOT_DETECTED;
     }
     s_state->sensor.slv_addr = slv_addr;
+    s_state->sensor.xclk_freq_hz = config->xclk_freq_hz;
 
     //s_state->sensor.slv_addr = 0x30;
     ESP_LOGD(TAG, "Detected camera at address=0x%02x", s_state->sensor.slv_addr);

driver/include/esp_camera.h

@@ -94,7 +94,7 @@ typedef struct {
     int pin_href;                   /*!< GPIO pin for camera HREF line */
     int pin_pclk;                   /*!< GPIO pin for camera PCLK line */
 
-    int xclk_freq_hz;               /*!< Frequency of XCLK signal, in Hz. Either 10KHz or 20KHz */
+    int xclk_freq_hz;               /*!< Frequency of XCLK signal, in Hz. Either 20KHz or 10KHz for OV2640 double FPS (Experimental) */
 
     ledc_timer_t ledc_timer;        /*!< LEDC timer to be used for generating XCLK  */
     ledc_channel_t ledc_channel;    /*!< LEDC channel to be used for generating XCLK  */

driver/include/sensor.h

@@ -86,6 +86,7 @@ typedef struct _sensor {
     uint8_t  slv_addr;          // Sensor I2C slave address.
     pixformat_t pixformat;
     camera_status_t status;
+    int xclk_freq_hz;
 
     // Sensor function pointers
     int  (*init_status)         (sensor_t *sensor);

sensors/ov2640.c

@@ -241,6 +241,15 @@ static int set_framesize(sensor_t *sensor, framesize_t framesize)
 
     WRITE_REG_OR_RETURN(BANK_DSP, R_BYPASS, R_BYPASS_DSP_BYPAS);
     WRITE_REGS_OR_RETURN(regs);
+    if (sensor->xclk_freq_hz == 10000000) {
+        if (framesize <= FRAMESIZE_CIF) {
+            WRITE_REG_OR_RETURN(BANK_SENSOR, CLKRC, CLKRC_2X_CIF);
+        } else if (framesize <= FRAMESIZE_SVGA) {
+            WRITE_REG_OR_RETURN(BANK_SENSOR, CLKRC, CLKRC_2X_SVGA);
+        } else {
+            WRITE_REG_OR_RETURN(BANK_SENSOR, CLKRC, CLKRC_2X_UXGA);
+        }
+    }
     WRITE_REG_OR_RETURN(BANK_DSP, ZMOW, (w>>2)&0xFF); // OUTW[7:0] (real/4)
     WRITE_REG_OR_RETURN(BANK_DSP, ZMOH, (h>>2)&0xFF); // OUTH[7:0] (real/4)
     WRITE_REG_OR_RETURN(BANK_DSP, ZMHH, ((h>>8)&0x04)|((w>>10)&0x03)); // OUTH[8]/OUTW[9:8]

sensors/private_include/ov2640_regs.h

@@ -209,5 +209,8 @@ typedef enum {
 #define REG32_CIF           0x89
 
 #define CLKRC_2X            0x80
+#define CLKRC_2X_UXGA       (0x01 | CLKRC_2X)
+#define CLKRC_2X_SVGA       CLKRC_2X
+#define CLKRC_2X_CIF        CLKRC_2X
 
 #endif //__REG_REGS_H__